Birth Defects in South Australia 2011

Transcription

1 Women s & Children s Hospital Birth Defects in South Australia 2011 South Australian Birth Defects Register Women s & Children s Hospital Adelaide, South Australia October 2015

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3 Birth Defects in South Australia 2011 Children born from 1986 to 2011 with birth defects notified to the South Australian Birth Defects Register by 31st March 2012

4 South Australian Birth Defects Register Location Specialist Advisors to the Register Health Informatics, Planning, Performance Outcomes Prof Eric Haan, Clinical Genetics (HIPPO) Unit A/Prof Bruce Foster, Orthopaedic Surgery Women s and Children s Hospital Campus Mr Peter Cundy, Orthopaedic Surgery Women s and Children s Health Network Prof David David, Craniofacial Surgery Ground Floor, Angas Building Dr Malcolm Richardson, Cardiology 72 King William Road Dr Hilary Boucaut, Urology North Adelaide, South Australia 5006 Dr Steve Santoreneos, Neurosurgery Telephone: (08) A/Prof Tom Revesz, Haematology/Oncology sabdr@health.sa.gov.au SABDR Website (to access online version of Birth Defects in South Australia and Prenatal Screening for Congenital Anomalies reports): Staff Ms Sacha Gower, Acting Head, SA Birth Defects Register Dr Wendy Scheil, Public Health Physician, Pregnancy Outcome Unit, SA Health Dr Catherine Gibson, Manager Ms Heather Scott, Manager Mrs Rosie Rice, Register Officer Advisory Committee Dr Geoffrey Martin, General Practitioner Dr Karen Shand, Obstetrician Dr Brian Peat, Obstetrician Dr Wendy Scheil, Representing SA Health Epidemiology Branch Dr Catherine Gibson, Representing the SA Birth Defects Register Ms Heather Scott, Representing the SA Birth Defects Register Prof Eric Haan, Clinical Geneticist Printing Rainbow Press PO Box 2221 Regency Park SA rainbowpress@senet.com.au Suggested Citation Gibson CS, Scott H, Scheil W. Birth Defects in South Australia Adelaide. SA Birth Defects Register, Women s and Children s Health Network, ISSN page 2 Birth Defects in South Australia 2011

5 Contents Contents Executive summary...7 Introduction...8 Demographics...9 Types of birth defects notified...15 Trends in selected birth defects, SA Sentinel defects...24 Deaths associated with birth defects...26 Sources of notification...28 Birth defects detected/notified after discharge from the birth hospital...28 Appendix...30 Birth Defects in South Australia 2011 page 3

6 Tables, Figures and Appendices Tables, Figures and Appendices Tables Table 1: Birth defects in children born in South Australia, Table 2: Cases with birth defects by residence of mother at time of birth, SA Table 3: Cases with birth defects by sex of child, SA Table 4: Cases with birth defects by mother s race, SA Table 5: Cases with birth defects by plurality, SA Table 6: Cases with specified birth defects by diagnostic category, SA Table 7: Cases of sentinel defects by CURB region, SA Table 8: Deaths associated with birth defects, SA Table 9: Cases with birth defects notified after discharge form the birth hospital by major diagnostic category, SA Figures Figure 1: Birth defects in children born in South Australia, Figure 2: South Australian CURB (Committee on Uniform Regional Boundaries) regions...11 Figure 3: Cases with birth defects by sex of child, SA Figure 4: Cases with birth defects by mother s race, SA Figure 5: Cases with birth defects by plurality, SA Figure 6: Cases with birth defects by major diagnostic category, SA (prevalence per 1,000 births)...15 Figure 7: Trends in selected birth defects, SA Figure 8: Prevalence of sentinel defects, SA Figure 9: Deaths associated with birth defects by death category, SA Figure 10: Figure 11: Sources of notification, SA : Total notifications received...28 Percentage of cases with birth defects notified after discharge from the birth hospital by diagnostic category, SA Appendix Appendix 1: Background information on the South Australian Birth Defects Register...30 Appendix 2: Confidentiality guidelines...31 Appendix 3: Notification form...34 Appendix 4: Birth defect inclusions and exclusions...35 page 4 Birth Defects in South Australia 2011

7 South Australian Birth Defects Register Staff South Australian Birth Defects Register Staff South Australian Birth Defects Register Staff Left to Right: Mrs Rosie Rice, Ms Heather Scott, Ms Sacha Gower, Dr Catherine Gibson, Dr Wendy Scheil Birth Defects in South Australia 2011 page 5

8 Acknowledgements Thanks to notifiers and acknowledgements We wish to thank all the notifiers who supplied the information on which this report is based. We greatly appreciate their support and advice, the time and effort they spend on completing the forms and their cooperation in supplying extra information when requested. In particular, we would like to express our thanks to the staff of the particular departments who have data collections or registers with which the Birth Defects Register interfaces: Women s and Children s Health Network: The Department of Cardiology for data on congenital heart defects, The Division of Medical Imaging for radiology and ultrasound information, The Medical Records Department. SA Pathology: Genetics and Molecular Pathology for cytogenetics reports, Down syndrome data, information on maternal serum screening, inborn errors of metabolism, abnormal neonatal screening results and data on prenatal diagnostic tests such as amniocentesis and chorionic villus sampling, Surgical Pathology for autopsy reports, Haematology. We also express thanks to the Medical Records Departments of South Australian metropolitan and regional hospitals, in particular Flinders Medical Centre, Lyell McEwin Health Service, The Memorial Hospital, Ashford Hospital, Calvary North Adelaide Hospital, St Andrew s Hospital and Parkwynd Private Hospital. We would like to thank all those people who have contributed to the South Australian Birth Defects Register since its inception. Their ongoing support and practical contribution is much appreciated. Special thanks are due to the staff of the Pregnancy Outcome Unit, particularly Joan Scott and Leonie Sage, for providing the important perinatal data and to Kevin Priest and AnhMinh Nguyen, the staff of the Health Statistics Unit of the Epidemiology Branch, SA Health for assistance with data linkage and statistical support. The Birth Defects Register Advisory Committee was established in June 1989 to advise the Register on issues of confidentiality and to review the activities of the Register. We thank its members for their time, expertise and valuable advice. Dr Geoffrey Martin, General Practitioner Dr Wendy Scheil, Epidemiology Branch of SA Health Prof Eric Haan, Clinical Geneticist Dr Karen Shand, Obstetrician Dr Brian Peat, Obstetrician The advice of many clinicians has been sought on the classification and coding of defects in specialised areas, eg. orthopaedics, craniofacial surgery, urology, neurosurgery and cardiology. We would like to express our gratitude to these consultants for their ongoing guidance. Thank you to Dr Bill Carey of Softcare Software for the creation and continued support of our computing software. Thanks to the WA Register of Developmental Anomalies, the Congenital Malformations Register of Victoria and the AIHW National Perinatal Statistics Unit for their ongoing support. page 6 Birth Defects in South Australia 2011

9 Executive Summary Executive summary This report presents data on birth defects in South Australia for The Register received 946 (4.7% of total births) notifications of children born with one or more birth defects in The proportion of total births with birth defects for the period was 5.9%. The difference represents the additional notifications, around 30%, received over the Register s further four year ascertainment period for each birth year cohort. In 2011 Demographics: The Murraylands CURB region recorded the highest proportions of births with birth defects, with 6.3% of total births, compared to the lowest proportion of 3.7% seen in the Northern CURB region. These differences are not statistically significant and reflect year to year variation in prevalence of birth defects and in ascertainment between regions. The prevalence of sentinel birth defects is similar across all regions when assessed over longer time periods. As seen in previous years, male sex and multiple births are associated with an increased risk of birth defects. Births to Aboriginal mothers had a higher proportion of birth defects (5.0%), compared with births to Caucasian mothers (4.9%) and Asian mothers (2.7%). Again, these data reflect year to year variation. Over the years , the proportion of birth defects was highest for Caucasian mothers (6.0%), followed by Aboriginal mothers (5.1%) and Asian mothers (4.3%). Neural tube defects and Down syndrome: There were 21 births or terminations with neural tube defects. The Register documented a significant decreasing trend in the prevalence of neural tube defects between 1986 and There were 53 births or terminations with Down syndrome. There is an increasing trend in the total prevalence of Down syndrome between 1986 and 2011, mostly due to increasing maternal age. Reported birth defects: The most commonly reported birth defects were musculoskeletal and urogenital abnormalities with 14.2 and 10.1 cases respectively per 1,000 total births. Chromosomal abnormalities had a prevalence of 5.8 per 1,000 total births. Deaths: 23.3% of spontaneous stillbirths and 34.1% of neonatal deaths were associated with birth defects. Late identification of birth defects: 19.8% of gastrointestinal defects and 24.7% of cardiovascular defects were identified after discharge from the birth hospital. The 2011 report of Prenatal Screening for Congenital Anomalies has been published separately and is available online ( Birth Defects in South Australia 2011 page 7

10 Introduction Introduction The South Australian Birth Defects Register is a populationbased collection of information on birth defects, including cerebral palsy, from a population with an average of 19,994 births per year over the past five years. The Register collects information on all children born in South Australia on or after 1st January 1986 who have a significant birth defect detected in the first five years of life. It thus complements and extends the collection of congenital abnormalities detected in the perinatal period and notified by doctors to the Pregnancy Outcome Unit of SA Health. The SA Birth Defects Register aims to provide complete, accurate and uptodate information for the following purposes: Establishing local prevalence rates for birth defects Monitoring the occurrence of defects over time and by geographical area to allow investigation of suspected teratogens Increasing community knowledge about birth defects through education and by acting as a source of information Utilisation of local prevalence rates to plan health care facilities Epidemiological studies on the causation of birth defects As an accurate diagnostic index for clinical research The Register defines a birth defect as any abnormality, structural or functional, identified up to five years of age, provided that the condition had its origin before birth. It includes: Terminations of pregnancy at any gestation performed because of a diagnosis of a birth defect, Stillbirths and newborn babies with birth defects, Children diagnosed with a birth defect after the neonatal period and prior to their fifth birthday. The Register is located in the Women s and Children s Hospital in the Health Informatics, Performance, Planning and Outcomes (HIPPO) Unit. This is an ideal location for the following reasons: The majority of children with birth defects requiring medical or surgical care are referred to the Women s and Children s Hospital for assessment or further management at some stage. The major paediatric diagnostic services and perinatal/paediatric pathology services are located at the Women s and Children s Hospital. Notifications of birth defects come from various sources including: Doctors and other health professionals involved with the care of children with birth defects in hospitals, special paediatric assessment, treatment and rehabilitation centres, private practices The Pregnancy Outcome Unit of SA Health The State Perinatal Autopsy Service Diagnostic services including laboratories diagnosing cytogenetic, molecular genetic or biochemical abnormalities, and organ imaging departments. This annual report presents information for the years , including birth defects notified up to March 2012 for children born in 2011 and updates numbers and rates for the years 2006 to Notifications for the cohorts of children born between 1986 and 2006 are now complete. All children in the 2006 cohort reached their fifth birthday by the end of 2011 and notifications of defects received by 31st March 2012 have been accepted for inclusion. After this date the 2006 cohort is considered complete and no further notifications are added. Similarly, the 2012 report will record complete numbers for the 2007 birth cohort. The 2011 report of Prenatal Screening for Congenital Anomalies has been published separately and is available online ( az/other/phru/birthdefect.html). For a full listing of publications and presentations utilising data from the SA Birth Defects Register please also refer to our website. For further information regarding the SA Birth Defects Register, Confidentiality Guidelines, Inclusion and Exclusion Lists, and a copy of the Notification Form, please refer to the Appendices at the end of this report. page 8 Birth Defects in South Australia 2011

11 Demographics Demographics This report includes all notifications of birth defects for births and terminations of pregnancy occurring in South Australia in the years and received by 31st March, The percentages and numbers of births with birth defects for the years are provided in Table 1 and Figure 1 respectively. As birth defects continue to be diagnosed and notified to the Register up to the age of 5 years, the percentage of births with birth defects is higher in cohorts with five completed years of ascertainment than in more recent cohorts (see Table 1). This is particularly true for defects such as congenital heart disease and urogenital malformations, which often are not diagnosed at birth. It is noteworthy that the percentage of total births with birth defects has not changed significantly since the Register began to collect data in Table 1: Birth defects in children born in South Australia, Year of Birth Total Births Cases of Birth Defects Percentage of Births With Birth Defects ,550 23, ,757 1, ,970 1, ,901 1, ,002 1, , Total 498,524 29, The numerator used in calculating the percentage is all South Australian births and terminations with birth defects. These consist of livebirths and stillbirths of at least 400g birthweight or 20 weeks gestation, and terminations of pregnancies of fetuses with birth defects. The denominator used is the total number of livebirths and stillbirths only, and excludes terminations of pregnancy before 20 weeks gestation. This makes our statistics comparable with those of other registers, but slightly overestimates the percentage of births with defects. This denominator has been selected also because accurate statistics on terminations may not be available elsewhere (as they are in South Australia), and fetuses from terminations in early pregnancy may not be examined for birth defects. Spontaneous fetal deaths, where weight is less than 400g and gestation is less than 20 weeks, are not included among the Register cases as accurate statistics on them are unavailable. Notifications of children with birth defects who were born outside South Australia in the years but who are currently resident in South Australia are not included in the statistics. Figure 1: Birth defects in children born in South Australia, Birth Defects in South Australia 2011 page 9

12 Demographics Residence of Mother Table 2 shows the distribution of cases by residence of mother at time of birth (see Figure 1). Births to mothers resident interstate had the highest prevalence of birth defects due to the referral of high risk pregnancies from interstate to Adelaide tertiary hospitals. In 2011, the Murraylands region recorded the highest percentage of cases with birth defects (6.3% of total births), compared with the lowest percentage (3.7%) in the Northern region. However, for the period , the Central Northern region had the highest overall percentage of birth defects (6.3%) and the South East region had the lowest overall percentage (4.9%). Over this period there was significant (χ 2 = , p<0.0001) variation in the prevalence of total birth defects between CURB regions. However, there was no significant difference between CURB regions (χ 2 = 2.66, p=0.10) for sentinel defects which are more reliably identified (Table 7). This suggests that the variation seen for total birth defects is due to differences in ascertainment between CURB regions. Table 2: Cases with birth defects by residence of mother at time of birth, SA CURB^ Region Year of Birth Total Central Northern 7258 (6.4) Central Western 3240 (6.3) Central Eastern 3718 (6.3) Central Southern 4933 (5.7) Yorke & Lower North 628 (5.7) Murraylands 1049 (5.4) South East 927 (4.9) Northern 1332 (5.1) Eyre 545 (5.1) Residence Interstate** or Unknown 300 (10.6) Total (6.0) 382 (6.3) 168 (7.0) 200 (6.5) 265 (6.0) 31 (6.3) 49 (5.9) 42 (4.8) 55 (5.1) 23 (5.3) 22 (19.0) 1237 (6.3) 372 (6.3) 167 (6.5) 185 (5.9) 282 (6.2) 30 (5.7) 45 (5.8) 43 (4.8) 57 (5.7) 13 (2.8) 19 (12.0) 1213 (6.1) 376 (6.2) 128 (5.2) 177 (5.8) 253 (5.6) 25 (5.0) 49 (6.0) 50 (6.0) 54 (5.1) 22 (4.4) 22 (18.5) 1156 (5.8) 327 (5.4) 124 (4.8) 154 (5.1) 259 (5.6) 17 (3.5) 50 (6.4) 34 (4.2) 41 (4.4) 23 (5.0) 28 (19.7) 1057 (5.3) *Number of children with birth defects in the region divided by the total number of births in the region x 100 ** Usual residence interstate but born in South Australia ^ Committee on Uniform Regional Boundaries (CURB) 313 (4.9) 128 (4.9) 116 (3.9) 210 (4.5) 20 (4.0) 48 (6.3) 33 (3.9) 38 (3.7) 20 (3.9) 20 (13.5) 946 (4.7) 9028 (6.3) 3955 (6.2) 4550 (6.1) 6202 (5.7) 751 (5.5) 1290 (5.5) 1129 (4.9) 1577 (5.1) 646 (5.0) 411 (11.7) (5.9) page 10 Birth Defects in South Australia 2011

13 Demographics Figure 2: South Australian CURB^ Regions ^Committee on Uniform Regional Boundaries (CURB) Birth Defects in South Australia 2011 page 11

14 Demographics Sex of Child The sex distribution of children born between 1986 and 2011 in South Australia with notified birth defects is shown in Table 3 and Figure 3. For , 57% of children notified were male and the ratio of males to females for birth defects was 1.37:1, i.e., 37% more male than female births were notified with a birth defect. This contrasts with a male to female ratio of 1.06:1 for all births. The percentage of male births with notified defects for the period was 6.5%; this was significantly higher (relative risk (RR) = 1.29 (95% CI ), p<0.0001), than for female births (5.1%). There are a number of birth defects that are specific to each sex (eg. undescended testis). Taking into account these sexspecific defects, there is still a greater prevalence of certain defects in males, for example pyloric stenosis, short segment Hirschsprung s disease and congenital talipes equinovarus. These defects are consistently found more often in males than in females. Table 3: Cases with birth defects by sex of child, SA Year of Birth Total Sex Male (6.6) 697 (6.9) 687 (6.8) 657 (6.4) 609 (5.9) 502 (4.8) (6.5) Female 9894 (5.1) 507 (5.2) 502 (5.1) 478 (5.0) 423 (4.4) 425 (4.3) (5.1) Indeterminate Not specified# Total (6.3) 1237 (6.3) 1213 (6.1) 1156 (5.8) 1057 (5.3) 946 (4.7) (5.9) * Percentage of births of that category in that year # These were all terminations of pregnancy Figure 3: Cases with birth defects by sex of child, SA page 12 Birth Defects in South Australia 2011

15 Demographics Race of Mother The distribution of births with birth defects by mother s race is shown in Table 4 and Figure 4. There were significant differences between the prevalences of birth defects according to mother s race for 2011 (χ 2 = 11.36, p<0.001), which were also seen for the period (χ 2 = , p<0.0001). For , 93% of cases notified to the SABDR had a Caucasian mother. There was a significantly higher prevalence of birth defects for Caucasian mothers compared with Asian (RR = 1.42, 95% CI ), Aboriginal (RR = 1.18, 95% CI ) and Other race (RR = 1.32, 95% CI ) mothers. Table 4: Cases with birth defects by mother s race, SA Mother s Race Year of Birth Total Caucasian (6.1) Aboriginal 484 (5.4) Asian 707 (4.6) Other 208 (4.5) Unspecified 58 Total (6.0) 1136 (6.6) 17 (2.9) 52 (4.3) 32 (5.2) (6.3) * Percentage of births of that category in that year 1105 (6.4) 25 (3.9) 58 (4.1) 25 (3.5) (6.1) 1016 (6.0) 31 (5.0) 65 (4.1) 44 (5.7) (5.8) 919 (5.6) 28 (4.4) 64 (3.3) 38 (4.2) (5.3) 804 (4.9) 35 (5.0) 62 (2.7) 44 (4.5) (4.7) (6.0) 620 (5.1) 1008 (4.3) 391 (4.6) (5.9) Figure 4: Cases with birth defects by mother s race, SA Birth Defects in South Australia 2011 page 13

16 Demographics Plurality The distribution of cases of birth defects by plurality is shown in Table 5 and Figure 5. Although 96% of cases notified for the 25 year period were singleton births, the percentage of cases among multiple births was 7.9%, and was significantly higher (RR = 1.31, 95% CI , p<0.0001) than among singleton births, with 5.9%. Certain birth defects are associated with twin pregnancies, in particular monozygotic twins. Examples of defects that occur more often in monozygotic twins are sirenomelia, VATER association, holoprosencephaly and anencephaly. Table 5: Cases with birth defects by plurality, SA Plurality Year of Birth Total Single (5.9) Multiple 941 (7.8) Total (6.0) 1193 (6.2) 44 (7.8) 1237 (6.3) * Percentage of births of that category in that year 1159 (6.0) 54 (9.1) 1213 (6.1) 1110 (5.7) 46 (7.8) 1156 (5.8) 1021 (5.3) 36 (5.4) 1057 (5.3) 909 (4.5) 37 (6.2) 946 (4.7) (5.9) 1158 (7.9) (5.9) Figure 5: Cases with birth defects by plurality, SA page 14 Birth Defects in South Australia 2011

17 Types of birth defects notified Types of birth defects notified The diagnostic categories used by the Register for coding are those of the British Paediatric Association (BPA) Classification of Diseases, 1979, a 5digit system compatible at the 4digit level with the ninth revision of the International Classification of Diseases (ICD9). Its Congenital Anomaly codes are those in the range The BPA also provides codes outside this range for some disorders which are included in the Register s collection. For disorders without a BPA code the Register uses the ICD9 classification. We anticipate a change in coding to the tenth revision of the International Classification of Diseases after a BPA ICD10AM system has been established nationally. The prevalences of birth defects per 1,000 total births for major diagnostic groupings (i.e. not all birth defects) are provided in Figure 6. The most commonly reported birth defects between 1986 and 2011 were Urogenital abnormalities with 16.8 per 1,000 births. In Table 6 we present the number of cases with specified birth defects by diagnostic category. Children with multiple defects will appear in more than one category. For example, a child with trisomy 18 who has spina bifida will appear in Chromosome defects and also under Nervous system defects and hence the number of cases in each body system total does not necessarily equal the sum of the individual defects listed under it. Within a specific category, e.g. Nervous system, the total may be smaller than the number obtained by adding together cases with anencephaly, spina bifida and encephalocele. This is because some cases of neural tube defects have more than one lesion, for example the combination of spina bifida and anencephaly. Figures 7.1 to 7.12 provide trends in selected birth defects 1986 to Figure 6: Cases with birth defects by major diagnostic category (prevalence per 1,000 births) Birth Defects in South Australia 2011 page 15

18 Types of birth defects notified Table 6: Cases with specified birth defects by diagnostic category, SA Year of Birth Diagnostic Category (BPA Code) Nervous System ( ) (per 1000*) 1625 (4.1) Total No (per 1000*) 87 (4.4) No (per 1000*) 82 (4.1) No (per 1000*) 104 (5.2) No (per 1000*) 78 (3.9) No (per 1000*) 76 (3.7) No per 1000* Neural tube defects Anencephaly Spina bifida Encephalocele Microcephaly Congenital hydrocephalus Cardiovascular ( ) 4856 (12.2) 246 (12.5) 265 (13.3) 233 (11.7) 214 (10.7) 198 (9.7) Transposition of great vessels Tetralogy of Fallot Ventricular septal defect Atrial septal defect Hypoplastic left heart syndrome Patent ductus arteriosus Coarctation of aorta Respiratory ( ) Pulmonary hypoplasia/ dysplasia Gastrointestinal ( ) 686 (1.7) 38 (1.9) 39 (2.0) 38 (1.9) 32 (1.6) 41 (2.0) (6.6) 134 (6.8) 128 (6.4) 116 (5.8) 114 (5.7) 111 (5.5) Cleft palate Cleft lip Cleft lip with cleft palate Tracheooesophageal fistula,oesophageal atresia & stenosis Pyloric stenosis Rectal/anal atresia & stenosis Hirschsprung disease Urogenital ( ) 6870 (17.2) 327 (16.6) 351 (17.6) 310 (15.6) 287 (14.3) 206 (10.1) Undescended testicle Hypospadias Renal agenesis & dysgenesis Vesicoureteric reflux * Prevalence per 1,000 total births page 16 Birth Defects in South Australia 2011

19 Types of birth defects notified Table 6: Cases with specified birth defects by diagnostic category, SA Year of Birth Diagnostic Category (BPA Code) Musculoskeletal ( ) (per 1000*) 6595 (16.5) Total No (per 1000*) 319 (16.1) No (per 1000*) 307 (15.4) No (per 1000*) 305 (15.3) No (per 1000*) 275 (13.7) No (per 1000*) 289 (14.2) No per 1000* Developmental dysplasia of hip Talipes equinovarus Polydactyly Syndactyly Reduction deformity of limbs Diaphragmatic hernia Exomphalos Gastroschisis Achondroplasia Osteogenesis imperfecta Chromosome ( ) 1566 (3.9) 108 (5.5) 116 (5.8) 126 (6.3) 101 (5.0) 117 (5.8) Down syndrome Trisomy Trisomy Turner syndrome Metabolic ( ) 563 (1.4) 27 (1.4) 28 (1.4) 35 (1.8) 21 (1.0) 20 (1.0) Congenital hypothyroidism Phenylketonuria Galactosaemia Albinism Cystic fibrosis Other metabolic Haematological/Immune ( ) 205 (0.5) 9 (0.5) 11 (0.6) 10 (0.5) 5 (0.2) 12 (0.6) Haemolytic anaemias Thalassaemias Coagulation defects Other selected Congenital syphilis syndrome Congenital rubella syndrome Fetal alcohol syndrome Nonimmune fetal hydrops Haemangioma Lymphangioma Anotia/Microtia * Prevalence per 1,000 total births Birth Defects in South Australia 2011 page 17

20 Trends in selected birth defects Trends in selected birth defects, SA Figure 7.1: Prevalence of neural tube defects, SA There was a significant downward trend in the prevalence of all neural tube defects for the period (Poisson regression, p<0.0001), and may be due to the increased use of periconceptional folic acid. However, a slowing of the downward trend occurred in 2009 and 2010 due to an increase in neural tube defect cases. After investigation*, it is reasonable to conclude that this increase in cases of neural tube defects is due to chance, although the need to improve universal health promotion messages regarding periconceptional folic acid supplementation in pregnancy is recognised. *Flood L, Scheil W, Nguyen A, Sage L, Scott J. An increase in neural tube defect notifications, South Australia, Western Pacific Surveillance and Response 2013; 4(2): 110. Figure 7.2: Prevalence of anencephaly, SA There was a significant downward trend in the prevalence of anencephaly for the period (Poisson regression, p=0.0026). This downward trend may be due to the increased use of periconceptional folic acid. page 18 Birth Defects in South Australia 2011

21 Trends in selected birth defects Figure 7.3: Prevalence of spina bifida, SA There was a significant downward trend in the prevalence of all spina bifida for the period (Poisson regression, p= ). This downward trend may be due to the increased use of periconceptional folic acid. Figure 7.4: Prevalence of total cleft lip, SA No significant trend was seen in the prevalence of total cleft lip (cleft lip alone and cleft lip with cleft palate) for the years (Poisson regression, p=0.65). Birth Defects in South Australia 2011 page 19

22 Trends in selected birth defects Figure 7.5: Prevalence of tetralogy of Fallot, SA No significant trend was seen in the prevalence of tetralogy of Fallot for the years , (Poisson regression, p=0.62). Figure 7.6: Prevalence of transposition of the great vessels, SA There was no significant trend in the prevalence of transposition of great vessels over the period (Poisson regression, p=0.17). page 20 Birth Defects in South Australia 2011

23 Trends in selected birth defects Figure 7.7: Prevalence of coarctation of the aorta, SA No significant trend was seen in the prevalence of coarctation of the aorta for the years , (Poisson regression, p=0.56). Figure 7.8: Prevalence of developmental dysplasia of the hip, SA There was a significant downward trend in the prevalence of developmental dysplasia of the hip over the period (Poisson regression, p<0.0072), but the prevalence appears to be relatively stable from 1995 onwards. Birth Defects in South Australia 2011 page 21

24 Trends in selected birth defects Figure 7.9: Prevalence of hypospadias, SA There was a significant upward trend in the five year prevalence of hypospadias for the years (Poisson regression, p<0.0001). From 1995, validation reviews between the SABDR and hospital data led to improved ascertainment and validation of cases not recorded at birth and undergoing surgery at a later date. There was no significant trend for the one year prevalence of hypospadias. Figure 7.10: Prevalence of renal agenesis/dysgenesis, SA No significant trend was seen in the prevalence of renal agenesis/dysgenesis for the years , (Poisson regression, p=0.65). page 22 Birth Defects in South Australia 2011

25 Trends in selected birth defects Figure 7.11: Prevalence of Down syndrome, SA Over the period , there was a significant increasing trend in the prevalence of Down syndrome (Poisson regression, p<0.0001). In the past, this increase has been attributed to increasing maternal age. However, even after adjustment for maternal age (using Poisson regression with cubic splines) the prevalence of Down syndrome still increases by 0.92% (95% CI 0.063% to 1.79%) every year. This indicates that other factors, in addition to maternal age, may be influencing the prevalence of Down syndrome. The risk of a future pregnancy being affected by Down syndrome is known to be increased for women who have already had a Down syndrome pregnancy*. Other potential explanations that may contribute to this increase could include paternal age, and technological advances in prenatal screening and diagnosis resulting in earlier case ascertainment prior to potential fetal demise. *De Souza, E, Halliday J, Chan A, Bower C, Morris J. Recurrence risks for Trisomies 13, 18 and 21. Am J Med Genet 149A: (2009) Figure 7.12: Incidence of Down syndrome by maternal age, SA As demonstrated by this figure, there is an exponential increase in the risk of Down syndrome with increasing maternal age. Birth Defects in South Australia 2011 page 23

26 Sentinel defects Sentinel defects A number of readily identifiable defects have been chosen as sentinel defects for monitoring purposes by the International Clearinghouse for Birth Defects Monitoring Systems. Figure 8 and Table 7 present sentinel defects by CURB region for the period The totals for individual defects may be less than those shown in Table 6 as births to women who are interstate residents have been excluded from this table. This tabulation is an important tool for detecting regional and temporal clusters of birth defects. The SABDR monitors the occurrence of defects over time and by geographical area in this way. The Register assesses the significance of variations in prevalence by comparing the observed and expected numbers for each region using the Poisson distribution. The prevalence of Down syndrome in the Central Eastern Region between 1986 and 2011 was again significantly greater than in the rest of South Australia (RR = 1.51, 95% CI , p<0.001). This was shown to be related to the older age of mothers in that region. After adjustment for maternal age, no significant difference was seen (MantelHaenszel RR = 1.08, 95% CI , p=0.37). There were no other significant regional increases in prevalence (p<0.01) between 1986 and Figure 8: Prevalence of sentinel defects, SA * Total cleft lip includes cleft lip with or without cleft palate page 24 Birth Defects in South Australia 2011

27 Sentinel defects Table 7: Cases of sentinel defects by CURB region, SA % State Births Central North Central West Central East CURB Region Central South Yorke & Low Nth Murray Lands South East North Eyre Total 28.9% 13.0% 15.0% 22.1% 2.7% 4.7% 4.7% 6.3% 2.6% 100% (per 1000*) Anencephaly 88 (0.61) Spina bifida 109 (0.76) Encephalocele 24 (0.17) Hydrocephalus 120 (0.84) Cleft palate 152 (1.06) Total cleft lip# 173 (1.21) Tracheooesophageal fistula, atresia & stenosis Anorectal atresia & stenosis 59 (0.41) 76 (0.53) Hypospadias 597 (4.17) Renal agenesis & dysgenesis Limb reduction defects Diaphragmatic hernia 76 (0.53) 115 (0.80) 45 (0.31) Exomphalos 48 (0.34) Gastroschisis 41 (0.29) Transposition of great vessels Hypoplastic left heart Down syndrome Anotia & Microtia 81 (0.57) 38 (0.27) 251 (1.75) 18 (0.13) Total 1968 (13.74) (per 1000*) 50 (0.78) 62 (0.96) 9 (0.14) 52 (0.81) 65 (1.01) 57 (0.89) 23 (0.36) 34 (0.53) 235 (3.66) 43 (0.67) 48 (0.75) 24 (0.37) 22 (0.34) 17 (0.26) 44 (0.68) 21 (0.33) 134 (2.08) 16 (0.25) 891 (13.86) (per 1000*) 45 (0.61) 57 (0.77) 9 (0.12) 59 (0.80) 58 (0.78) 78 (1.05) 37 (0.50) 42 (0.57) 268 (3.61) 44 (0.59) 55 (0.74) 27 (0.36) 28 (0.38) 9 (0.12) 42 (0.57) 21 (0.28) 212 (2.86) 10 (0.13) 1020 (13.76) (per 1000*) 69 (0.63) 79 (0.72) 13 (0.12) 97 (0.89) 98 (0.90) 121 (1.11) 36 (0.33) 56 (0.51) 396 (3.62) 65 (0.59) 77 (0.70) 38 (0.35) 41 (0.38) 17 (0.16) 82 (0.75) 35 (0.32) 250 (2.29) 17 (0.16) 1472 (13.47) (per 1000*) 10 (0.74) 8 (0.59) 3 (0.22) 8 (0.59) 9 (0.66) 19 (1.40) 5 (0.37) 6 (0.44) 54 (3.98) 9 (0.66) 15 (1.11) 8 (0.59) 6 (0.44) 1 (0.07) 9 (0.66) 4 (0.30) 30 (2.21) 1 (0.07) 182 (13.43) * Prevalence per 1,000 total births in region; # cleft lip with or without cleft palate (per 1000*) 16 (0.69) 21 (0.90) 1 (0.04) 17 (0.73) 22 (0.94) 28 (1.20) 10 (0.43) 11 (0.47) 97 (4.16) 13 (0.56) 28 (1.20) 12 (0.51) 8 (0.34) 8 (0.34) 15 (0.64) 3 (0.13) 41 (1.76) 0 (0.00) 325 (13.95) (per 1000*) 12 (0.52) 17 (0.73) 3 (0.13) 12 (0.52) 23 (0.99) 24 (1.04) 5 (0.22) 11 (0.48) 85 (3.67) 9 (0.39) 16 (0.69) 9 (0.39) 8 (0.35) 5 (0.22) 12 (0.52) 9 (0.39) 37 (1.60) 4 (0.17) 281 (12.14) (per 1000*) 25 (0.80) 29 (0.93) 4 (0.13) 24 (0.77) 24 (0.77) 36 (1.16) 13 (0.42) 16 (0.51) 117 (3.76) 25 (0.80) 31 (1.00) 18 (0.58) 18 (0.58) 13 (0.42) 14 (0.45) 7 (0.22) 33 (1.06) 2 (0.06) 408 (13.10) (per 1000*) 11 (0.85) 12 (0.93) 2 (0.15) 7 (0.54) 18 (1.39) 16 (1.24) 4 (0.31) 5 (0.39) 57 (4.40) 3 (0.23) 10 (0.77) 6 (0.46) 6 (0.46) 2 (0.15) 7 (0.54) 4 (0.31) 15 (1.16) 2 (0.15) 169 (13.05) (per 1000*) 326 (0.66) 394 (0.80) 68 (0.14) 396 (0.80) 469 (0.95) 552 (1.12) 192 (0.39) 257 (0.52) 1906 (3.85) 287 (0.58) 395 (0.80) 187 (0.38) 185 (0.37) 113 (0.23) 306 (0.62) 142 (0.29) 1003 (2.03) 70 (0.14) 6716 (13.57) Birth Defects in South Australia 2011 page 25

28 Deaths associated with birth defects Deaths associated with birth defects In Table 8, the number of deaths associated with birth defects is listed by death category. Note that the birth defect is not necessarily the cause of death. In 2011, spontaneous stillbirths with birth defects represented 23.3% of all spontaneous stillbirths in South Australia and neonatal deaths with birth defects represented 34.1% of all neonatal deaths in the same period. Overall, for the period , spontaneous stillbirths with birth defects represented 12.9% of all spontaneous stillbirths, whilst neonatal deaths with birth defects represented 31.1% of all neonatal deaths. Figure 9 shows deaths associated with birth defects for the years by category of death. The different death categories are mutually exclusive. For example, the stillbirth category does not include terminations of pregnancy 20 weeks gestation. In the category termination of pregnancy <20 weeks gestation, the Register distinguishes between first and second trimester diagnoses. Some notifications specify whether testing has been by chorionic villus sampling or amniocentesis. Otherwise, classification into these two groups is based on gestation. At a gestation of < 14 weeks, diagnosis is assumed to be via chorionic villus sampling or ultrasound. At a gestation of 14 weeks, diagnosis is assumed to be via amniocentesis or ultrasound. Figure 9: Deaths associated with birth defects by death category, SA page 26 Birth Defects in South Australia 2011

29 Deaths associated with birth defects Table 8: Deaths associated with birth defects, SA Death Category Post Neonatal Death (death of a liveborn infant between 28 days of age and the first birthday) Neonatal Death (death of a liveborn infant before 28 days of age) (6.7) 429 (14.1) Year of Birth Total (3.1) 17 (8.9) 9 (4.7) 12 (6.3) 8 (3.9) 16 (7.8) 7 (3.5) 15 (7.4) 7 (3.2) 15 (6.9) 242 (6.0) 504 (12.4) Stillbirth (spontaneous fetal death 20 weeks) 312 (10.2) 22 (11.5) 22 (11.5) 18 (8.7) 25 (12.4) 35 (16.1) 434 (10.7) Termination of Pregnancy ( 20 weeks) 617 (20.2) 46 (24.0) 55 (28.6) 51 (24.8) 43 (21.3) 52 (23.9) 864 (21.3) Termination of Pregnancy (< 20 weeks) Diagnosis by chorionic villus sampling and/or ultrasound in first trimester Diagnosis by amniocentesis, cordocentesis and/or ultrasound after first trimester All Termination of Pregnancy (any gestation) 279 (9.2) 1205 (39.5) 2101 (69.0) 38 (19.8) 63 (32.8) 147 (76.6) 38 (19.8) 56 (29.2) 149 (77.6) 43 (20.9) 70 (34.0) 164 (79.6) 39 (19.3) 73 (36.1) 155 (76.7) 28 (12.8) 81 (37.2) 161 (73.9) 465 (11.5) 1548 (38.2) 2877 (70.9) Total * Percentage of total deaths associated with birth defects in that year Birth Defects in South Australia 2011 page 27

30 Sources of notification Sources of notification The sources of notification for cases born in are provided in Figure 10. As outlined earlier, each case may be notified by more than one source and considerable checking is required by the Register to validate the information. Notifications from the Pregnancy Outcome Statistics Unit are obtained from all obstetric units as well as homebirth midwives in South Australia. Figure 10: Sources of notification, SA : Total notifications received* *Each case may have multiple notifications Birth defects detected / notified after discharge from the birth hospital Table 9 and Figure 11 use diagnostic categories to show the number and proportion of cases of birth defects in which were detected and notified after discharge from the birth hospital. Over 50% of cardiovascular, urogenital, haematological/immune and metabolic defects were notified after discharge from the birth hospital. The value of the Register in collecting later diagnosed defects is clearly illustrated by the proportions of cases in these latter categories, especially for earlier birth cohorts where collection has been of longer duration. The use of the Integrated South Australian Activity Collection (ISAAC), which is an admitted patient morbidity data collection, largely contributes to the validation of cases by SABDR staff, and this is reflected in the majority of cases being notified from the Women s and Children s Hospital as shown in Figure 10. Examples of birth defects that are commonly notified after discharge form the birth hospital are ventricular septal defects, vesicoureteric reflux, craniosynostosis and pyloric stenosis. page 28 Birth Defects in South Australia 2011

31 Birth defects detected/notified after discharge from the birth hospital Table 9: Cases with birth defects notified after discharge from the birth hospital by major diagnostic category, SA Year of Birth Total Diagnostic Category Nervous System 505 (31.1) 30 (34.5) 25 (30.5) 29 (27.9) 14 (17.9) 11 (14.5) 614 (29.9) Cardiovascular 2680 (55.2) 117 (47.6) 120 (45.3) 99 (42.5) 82 (38.3) 49 (24.7) 3147 (52.3) Respiratory 124 (18.1) 10 (26.3) 2 (5.1) 6 (15.8) 3 (9.4) 1 (2.4) 146 (16.7) Gastrointestinal 1099 (42.0) 43 (32.1) 42 (32.8) 36 (31.0) 32 (28.1) 22 (19.8) 1274 (39.6) Urogenital 4190 (61.0) 183 (56.0) 199 (56.7) 172 (55.5) 112 (39.0) 50 (24.3) 4906 (58.7) Musculoskeletal 2101 (31.9) 107 (33.5) 99 (32.2) 88 (28.9) 68 (24.7) 68 (23.5) 2531 (31.3) Chromosomal 184 (11.7) 12 (11.1) 11 (9.5) 8 (6.3) 4 (4.0) 0 (0.0) 219 (10.3) Metabolic 378 (67.1) 16 (59.3) 16 (57.1) 19 (54.3) 6 (28.6) 7 (35.0) 442 (63.7) Haematological/ Immune Disorders 129 (62.9) 8 (88.9) 10 (90.9) 5 (50.0) 3 (60.0) 0 (0.0) 155 (61.5) * Percentage of total cases per category, per year Figure 11: Percentage of cases with birth defects notified after discharge from the birth hospital by diagnostic category, SA Birth Defects in South Australia 2011 page 29

32 Appendix 1 Appendix 1: Background information on the SA Birth Defects Register 1. Aims The Birth Defects Register aims to provide complete, accurate and uptodate information for the following purposes: Establishing local prevalence rates for birth defects Monitoring the occurrence of defects over time and by geographical area to allow investigation of suspected teratogens Increasing community knowledge about birth defects through education and by acting as a source of information Utilisation of local prevalence rates to plan health care facilities Epidemiological studies on the causation of birth defects As an accurate diagnostic index for clinical research 2. Sources of Notification Cases notified to the Register include those with birth defects detected in a variety of circumstances: Pregnancies terminated because of a diagnosis of a birth defect in the fetus Late fetal deaths (stillbirths) Newborn babies Children diagnosed after the neonatal period and prior to their fifth birthday The sources of notification include: Doctors and other health professionals involved with the care of children with birth defects in hospitals, special paediatric assessment, treatment and rehabilitation centres and private practices The Pregnancy Outcome Statistics Unit of SA Health The State Perinatal Autopsy Service and other pathology services Diagnostic services including laboratories diagnosing cytogenetic or biochemical abnormalities, and organ imaging departments. While notifications of defects detected prenatally are made by doctors to the Pregnancy Outcome Statistics Unit, it is recognised that many defects, for example some congenital heart defects or malformations of the urinary tract, may not be detected at the time of birth. Moreover, diagnoses made in the neonatal period may change with time. The Register, by extending the period of time for receiving notifications, and receiving them from multiple sources, achieves more complete ascertainment of birth defects in South Australian children (The notification form is included in Appendix 3). 3. Definition of a Birth Defect A birth defect is defined within the Register as any abnormality, structural or functional, identified up to five years of age, provided that the condition had its origin before birth. Thus, structural (eg. spina bifida), chromosomal (eg. Down syndrome) and biochemical (eg. phenylketonuria) defects are included. For Register purposes, single gene defects, eg. Neurofibromatosis, cystic fibrosis and muscular dystrophy, are also considered to be birth defects, although clinical manifestations may not appear until well after birth, and some may not cause malformations. Most minor malformations are excluded unless they are disfiguring, require treatment, or accompany another defect. (A list of inclusions and exclusions is provided in Appendix 4). 4. Ascertainment and Accuracy of Diagnoses Ascertainment of birth defects will be incomplete in the first few years of life of each birth cohort. Data collection to five years of age, the use of multiple notification sources, and confirmation of diagnoses by clinicians and pathologists increases the accuracy of final diagnoses, and with it the value of the Register. 5. Confidentiality of Data The Register has detailed and comprehensive confidentiality guidelines (Appendix 2). The guidelines ensure the confidentiality of the Register s data, while allowing research to be carried out in accordance with the National Health and Medical Research Council Guidelines for Epidemiological Research. Confidentiality of Register data is overseen by the Birth Defects Register Advisory Committee. This Committee reviews the operation of the Register and comments on research proposals involving Register data. page 30 Birth Defects in South Australia 2011

33 Appendix 2 Appendix 2: Confidentiality guidelines The South Australian Birth Defects Register receives notifications of children with birth defects under the provisions of Part 7 of the South Australian Health Care Act, Although notification does not require parental consent, provisions are made to inform public and parents about the Register. Part 7 requires the Register to maintain the confidentiality of notified information, whilst allowing the release of data to certain persons for specified purposes. The Register has developed guidelines to enable the confidential management of personal information in accordance with the provisions of Part 7. Since September 1999, notification of children with birth defects identified later, ie after discharge from the hospital of birth but before the child s fifth birthday, has been required under legislation (South Australian Health Care Regulations, 2008). This notification is required to be made to the Pregnancy Outcome Statistics Unit of SA Health, which also receives notification of birth defects detected at birth under the same legislation. The Pregnancy Outcome Statistics Unit has asked the SA Birth Defects Register to assist it in the collection of late notifications of children with birth defects. The historical data collected under the South Australian Health Care Act continue to be subject to the privacy provisions of that Act. Purpose of Confidentiality Guidelines The purpose of confidentiality guidelines is: To protect the privacy of children and women notified to the Register and the confidentiality of the information received; To ensure confidentiality by documenting procedures for managing personal information in a confidential manner; To ensure a balance between individual privacy and the confidentiality of information held by the Register, and the public benefit arising from knowledge of the frequency, cause, prevention and treatment of birth defects through the use of the Register; To ensure that the Register data are of the best quality possible. Data quality is dependent on the use of identified personal information in a confidential manner in accordance with these guidelines; To ensure that the Register retains the support of notifying health professionals by managing the information they notify in a confidential manner; To facilitate the best possible use of Register data for the benefit of the community and promotion of best practice medicine. Responsibility for Confidentiality Responsibility for the confidentiality of the Birth Defects Register s data lies with the Head, Health Informatics, Planning Performance Outcomes Unit and ultimately with the Board of Management of the Women s and Children s Hospital through the hospital s line management structure. The SA Birth Defects Advisory Committee advises the Register on the preservation of confidentiality of data collected by the Register. Membership of the Advisory Committee is: Professor Eric Haan, Clinical Geneticist Dr Wendy Scheil, Public Health Physician Dr Geoff Martin, General Practitioner Dr Karen Shand, Obstetrician Dr Brian Peat, Obstetrician Ethical Principles Governing Research Conducted by the Register The Register uses the National Health and Medical Research Council s National Statement on Ethical Conduct in Research Involving Humans (1999) when considering research proposals. Section 14, Epidemiological Research describes the conditions under which research can be undertaken. Principles and Procedures for Ensuring Confidentiality While Managing Personal Information 1 Release of Information 1.1 Routine Reports All routine reports from the Register, such as the Annual Report, are in statistical form without the identification of individual patients, doctors or hospitals. Unnamed statistical information that may be identifiable to particular recipients is not released. Birth Defects in South Australia 2011 page 31