Maternal panic disorder and congenital abnormalities: a population-based case-control study

BACKGROUND: Maternal panic disorder in pregnancy is the most common manifestation of anxiety disorders in Hungary. The association between panic disorder during pregnancy and structural birth defects, i.e., congenital abnormalities, was studied. METHODS: The prevalence of maternal panic disorder in cases with different congenital abnormalities was compared to that of matched controls in the population-based Hungarian Case-Control Surveillance System of Congenital Abnormalities. RESULTS: Of 22,843 cases with congenital abnormalities, 210 (0.9%) had mothers with panic disorder during pregnancy compared to 187 (0.5%) of 38,151 controls (adjusted prevalence odds ratio [POR] 1.6; 95% CI, 1.3-2.0). Specific groups of congenital abnormalities were also assessed versus controls. Cases with isolated cleft lip with or without cleft palate (CL/P) (adjusted POR, 3.4; 95% CI, 1.3-9.0) and multiple congenital abnormalities (adjusted POR, 3.0; 95% CI, 1.2-7.2) were more likely to have had mothers with panic disorder during the study pregnancy. Notably, among mothers with panic disorders, the associations were found only in offspring of untreated mothers. CONCLUSIONS: A higher rate of isolated CL/P and multiple congenital abnormalities may be caused by the direct biological effect of panic disorder or by the interaction of maternal panic disorder and lifestyle factors. Antipanic drug treatment seems to have a protective effect for isolated CL/P and multiple congenital abnormalities. Birth Defects Research (Part A), 2006.     

Maternal severe migraine and risk of congenital limb deficiencies

BACKGROUND: Migraines occurs frequently during pregnancy; however, there are no published data on their possible teratogenic potential in a controlled epidemiological study. Therefore, we examined the risk of congenital abnormalities in infants born to women who had migraines and other headaches during pregnancy. METHODS: Between 1980 and 1996, the Hungarian Case-Control Surveillance of Congenital Abnormalities evaluated 22,843 cases (newborns or fetuses) with congenital abnormalities, 38,151 control newborn infants without any abnormalities, and 834 malformed controls with Down syndrome. RESULTS: Migraines anytime during pregnancy occurred in 565 (2.5%) mothers of the case group compared with 713 (1.9%) mothers in the control group (crude prevalence odds ratio [POR], 1.3; 95% confidence interval [CI], 1.2-1.5) and 24 (2.9%) pregnant women in the malformed control group (crude POR, 0.9; 95% CI, 0.6-1.3) The mothers of 247 cases, 533 controls, and 21 malformed controls had severe migraines during the second and/or third months of pregnancy. There was only 1 congenital abnormality group: limb deficiencies, which had a higher rate of maternal migraines during the second and third months of pregnancy both at the comparison of cases and matched controls (adjusted POR, 2.5; 95% CI, 1.1-5.8) and of cases and malformed controls (adjusted POR, 1.7; 95% CI, 1.3-3.0). There was no association between other headaches and different congenital abnormalities at the comparison of cases and controls. CONCLUSIONS: Our data showed that maternal severe migraines during the second and/or third months of pregnancy were associated with an increased risk of congenital limb deficiencies. A similar association was not detected between congenital anomalies and other headaches during pregnancy. Our study was not based on a prior hypothesis; therefore, these data can be considered only as a signal that needs confirmation by independent data sets.     

Maternal influenza during pregnancy and risk of congenital abnormalities in offspring

BACKGROUND: The teratogenic effect of influenza viruses is currently being debated, and we examined the large population-based data set of the Hungarian Case-Control Surveillance of Congenital Abnormalities (HCCSCA) to study the possible association between maternal influenza and various congenital abnormalities (CAs). METHODS: The 1980-1996 HCCSCA includes 22,843 newborns or fetuses with CAs, and 38,151 matched controls (newborn infants without any abnormalities). RESULTS: In the case group, 1328 (5.8%) mothers had influenza at some time during their pregnancies compared to 1838 (4.8%) mothers in the control group (adjusted prevalence odds ratios [PORs], 1.3; 95% confidence interval [CI], 1.2-1.4). In the calculation of the adjusted PORs, the use of antifever drugs and maternal employment status were considered. When cases and their matched controls were compared, there was a higher prevalence of maternal influenza during the second and/or third month of pregnancy for the group of newborns with cleft lip +/- palate (adjusted POR, 3.2; 95% CI, 2.0-5.3), neural-tube defects (adjusted POR, 1.9; 95% CI, 1.1-3.3), and cardiovascular malformations (adjusted POR, 1.7; 95% CI, 1.3-2.3). However, a direct teratogenic effect from influenza viruses appears to be unlikely, and we suggest that the higher prevalence of the CAs indicated above can be explained mainly by fever, because this risk was reduced by the use of antifever drugs. Periconceptional folic acid supplementation also showed some preventive effect for these CAs. CONCLUSIONS: The indirect teratogenic effect of maternal influenza during pregnancy may be restricted by appropriate medical treatment (e.g., antifever drugs) and periconceptional folic acid supplementation.     

Evaluation of drug intake during pregnancy in the Hungarian Case-Control Surveillance of Congenital Anomalies

The data of the Hungarian Case-Control Surveillance of Congenital Anomalies, 1980-1987, were evaluated concerning drug intake during pregnancy in 10,698 index patients, 21,546 negative controls, and 828 positive controls (Down syndrome). Excluding pregnancy supplements, the proportion of no drug use was about 30% and the mean number of drugs used was 2.0 in the negative control group. These figures did not differ significantly from data of study and positive control groups. The analysis of most commonly used drugs indicated an extremely high proportion of hormonal support therapy. The teratogenic effect of several human teratogenic drugs was confirmed. However, their use is relatively rare and their attributable risk within the etiology of congenital anomalies is low, at about 0.3-1.0%. At present the teratogenic risk of drugs in humans is exaggerated and it has several unfortunate consequences: negligence in necessary drug use, unnecessary anxiety in pregnant women, and termination of planned pregnancies without any reasonable cause.     

Maternal diseases and isolated orofacial clefts in Hungary

BACKGROUND: Isolated orofacial clefts (OFCs) are likely to be caused by gene-environment interaction; therefore, the objective of the current study was to evaluate the possible association between all maternal diseases during pregnancy and isolated cleft lip with or without cleft palate (CL+/-CP) and posterior cleft palate (PCP) in the offspring. METHODS: The database of the large population-based Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996, was evaluated. The database includes 1374 cases with isolated CL+/- CP and 601 with PCP, plus 38,151 matched population controls (without defects) and 20,868 patient controls with other defects. Data collection was based on prospective medical records, retrospective maternal data via a self-reported questionnaire, and home visits of nonresponding families. RESULTS: An increased risk for isolated CL+/- CP was found for children born to mothers with influenza, common cold, orofacial herpes, and gastroenteritis during pregnancy. Risk for isolated PCP was increased in children of mothers with influenza, sinusitis, and bronchitis. Among chronic maternal diseases, epilepsy and angina pectoris showed a higher prevalence in the mothers of children born with isolated OFCs (cases). CONCLUSIONS: Some maternal diseases are risk factors for the pathogenesis of isolated OFCs. It is worth considering the prevention of possible harmful effects of influenza by vaccination during the expected epidemic period.     

Population-based case-control study of isolated congenital cataract

BACKGROUND: The aim of this study was to detect possible etiological factors in the origin of isolated congenital cataracts. METHODS: The data set of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-2002, contains 111 cases of isolated congenital cataract and 111 matched control pairs without the defect, 37,837 population controls without any defects, and 22,744 malformed controls with other nonocular abnormalities. Exposure data and family history are based on prospective medical records, retrospective maternal information, and information obtained by regional nurses during a home visit with nonrespondent mothers. RESULTS: A positive family history indicated an autosomal-dominant origin in 10% of cases. Rubella infections occurred more frequently in case mothers than in control mothers before vaccination against rubella virus was instituted. A higher prevalence of influenza or common cold during pregnancy was found in the case group (55.9%) than in the population control group (18.5%; adjusted odds ratios [ORs], 5.8; 95% confidence interval (CI), 4.0-8.4) or in the malformed control group (21.7%; adjusted OR, 4.7; 95% CI, 3.2-6.9). The prevalence of acute infectious diseases of the respiratory system during pregnancy was also higher in the case group (26.1%) than in the population control group (9.1%; adjusted OR, 3.8; 95% CI, 2.5-5.8), or the malformed control group (9.3%; adjusted OR, 3.4; 95% CI, 2.3-5.3). The higher risk for isolated congenital cataract in cases of mothers with influenza or common cold and acute infectious diseases of the respiratory system during pregnancy was not found after administration of antifever therapy. CONCLUSIONS: Some isolated congenital cataracts are preventable by rubella vaccination and probably by influenza vaccination in the epidemic period. In addition, our results suggest that using antifever therapy for fever-related respiratory diseases may restrict the teratogenic risk of hyperthermia.     

Use of specified critical periods of different congenital abnormalities instead of the first trimester concept

BACKGROUND: Previously the first trimester, later the 2nd and/or 3rd gestational months were evaluated at the analysis of different exposures in different congenital abnormalities. However, different congenital abnormalities have different critical periods. The objective of this study was to check the feasibility of a new approach to consider the specified critical periods of different congenital abnormalities separately. METHODS: The potential teratogenic effect of oral ampicillin treatment and maternal influenza/fever during the study pregnancy regarding any time in pregnancy, during the first trimester, in the 2nd and/or 3rd gestational months, and finally in the specified critical periods of given congenital abnormalities were evaluated in the population‐based large data set of the Hungarian Case‐Control Surveillance System of Congenital Abnormalities. RESULTS: Of 22,843 cases, 1644 (7.2%) and 1328 (5.8%) were born to mothers who had oral ampicillin treatment or were affected with influenza/fever during the study pregnancy, while of 38,151 control newborns without any defect, 2631 (6.9 %) and 1838 (4.8%) had mothers with ampicillin treatment or influenza/fever, respectively. The analysis of different exposure time windows showed some difference in the risk for congenital abnormalities. The use of specified critical periods of different congenital abnormalities was feasible. CONCLUSIONS: The use of specified critical periods of different congenital abnormalities seems to be more scientific‐based than the previously accepted methods for the evaluation of different exposure time windows. Thus this new and feasible approach is recommended for the controlled epidemiological studies in the future after an international consensus in the specified critical periods of different congenital abnormalities and other methodological issues. © 2008 Wiley‐Liss, Inc.     

International Commission for Protection against Environmental Mutagens and Carcinogens. ICPEMC Working Paper No. 10. A new approach to germinal mutation surveillance: pair-wise evaluation of component elements in unidentified multiple congenital abnormalities

In the Hungarian population-based surveillance of germinal mutations, 3 indicator conditions of offspring are being followed, namely 15 sentinel anomalies, Down syndrome and unidentified multiple congenital abnormality. The latter is discussed here as a possible indicator of germinal dominant gene and chromosomal mutations. The component congenital abnormalities of unidentified multiple congenital abnormalities are classified into 45 groups. The component congenital abnormalities were reduced to pairs. A pair is a set of 2 independent component congenital abnormalities in index patients with 2 or more congenital abnormalities. Baseline figures of all component congenital abnormality pairs in 3722 unidentified multiple congenital abnormalities were determined in the study period 1973-1982. The observed data for 1983 were compared with expected occurrences based on baseline figures. This pair-wise evaluation of component elements within unidentified multiple congenital abnormalities seems to be an adequate surveillance method to detect any time cluster of congenital abnormality pairs due to environmental factors including germinal mutagens.     

A new approach to germinal mutation surveillance: pair-wise evaluation of component elements in unidentified multiple congenital abnormalities

In the Hungarian population-based surveillance of germinal mutations, 3 indicator conditions of offspring are being followed, namely 15 sentinel anomalies, Down syndrome and unidentified multiple congenital abnormality. The latter is discussed here as a possible indicator of germinal dominant gene and chromosomal mutations. The component congential abnormalities of unidentified multiple congenital abnormalities are classified into 45 groups. The component congenital abnormalities were reduced to pairs. A pair is a set of 2 independent component congenital abnormalities in index patients with 2 or more congenital abnormalities. Baseline figures of all component congenital abnormality pairs in 3722 unidentified multiple congenital abnormalities were determined in the study period 1973–1982. The observed data for 1983 were compared with expected occurrences based on baseline figures. This pair-wise evaluation of component elements within unidentified multiple congenital abnormalities seems to be an adequate surveillance method to detect any time cluster of congenital abnormality pairs due to environmental factors including germinal mutagens.     

ABCDXXX: The obscenity of postmarketing surveillance for teratogenic effects

Our current system of postmarketing surveillance, which is based on voluntary reporting of suspected teratogenic effects, is a failure. Postmarketing surveillance should, at a minimum, provide reassurance that every approved drug treatment does not produce a teratogenic effect as great as thalidomide embryopathy or fetal alcohol syndrome. This means that postmarketing surveillance should be able to detect a twofold or greater increase in the frequency of major congenital anomalies, a fivefold or greater increase in the frequency of intellectual disability, or a characteristic pattern of minor anomalies and functional abnormalities that occurs with a frequency of at least 10% among the children of women who were treated with the drug during pregnancy. Effective surveillance for teratogenic effects could be accomplished through a complementary set of mechanisms that includes pregnancy exposure registries or cohorts as well as direct examination of a small subset of infants whose mothers received the treatment during various periods of pregnancy. If this routine surveillance reveals a "signal" (i.e., an indication suggesting a possible teratogenic effect), further study would be needed to establish whether the observed effect is real and causal. Once a signal of possible teratogenicity in humans has been recognized, validating or refuting it would become an urgent matter. Birth Defects Research (Part A) 94:670-676, 2012. ? 2012 Wiley Periodicals, Inc.     

What proportion of congenital abnormalities can be prevented?

OBJECTIVE--To estimate the proportion of preventable congenital abnormalities in Hungary. DESIGN--Analysis of available Hungarian data-bases and of the effectiveness of primary, secondary, and tertiary preventive methods. SETTING--Databases of ad hoc epidemiological studies and of the Hungarian congenital abnormality registry. MAIN OUTCOME MEASURES--Prevalence at birth and prevalence after prevention in 73 congenital abnormality types or groups. RESULTS--Preventive methods are available for 51 (70%) of the 73 congenital abnormality types or groups evaluated. The birth prevalence of all congenital abnormalities could be reduced from 65 to 26 per 1000; thus 39 per 1000 (60%) are preventable. Without congenital dislocation of the hip, which is unusually common in Hungary, the preventable proportion of congenital abnormalities is 52%. CONCLUSION--Many congenital abnormalities can be prevented, but as they do not represent a single pathological category there is no single strategy for their prevention.     

Hungarian surveillance of germinal mutations

Summary The Hungarian surveillance of germinal mutations is based on three indicator conditions seen in offspring, i.e., 15 sentinel anomalies, Down syndrome and component anomaly pairs of unidentified multiple congenital anomalies. It is an opportunistic program, because the necessary data are available from the Hungarian Congenital Malformation Registry. This system is described and the criteria of a good registry are summarized. The analysis of indicator conditions caused by germinal mutations did not reveal any measurable mutagenic effects in Hungary following the accident at the Chernobyl nuclear power plant. The pros and cons of germinal mutation surveillance are discussed.     

Alberta Congenital Anomalies Surveillance System.

The Alberta Congenital Anomalies Surveillance System was started in 1966 in response to the thalidomide tragedy earlier in the decade. It was one of four provincial surveillance systems on which the federal government relied for baseline statistics of congenital anomalies. The government now collects data from six provinces and one territory. The Alberta Congenital Anomaly Surveillance System originally depended on three types of notification to the Division of Vital Statistics, Department of Health, Government of Alberta: birth notice and certificates of death and stillbirth; increased sources of ascertainment have greatly improved data quality. We present the data for 1980-86 and compare the prevalence rates of selected anomalies with the rates from three other surveillance systems. Surveillance systems do not guarantee that a new teratogen will be detected, but they are extremely valuable for testing hypotheses regarding causation. At the very least they provide baseline data with which to compare any deviation or trend. For many, if not most, congenital anomalies total prevention is not possible; however, surveillance systems can be used to measure progress in prevention.     

Smoking during pregnancy and congenital limb deficiency.

OBJECTIVE--To examine genetic and environmental factors in the origin of isolated congenital limb deficiencies. DESIGN--Case-control study with questionnaire at a family interview of cases of isolated congenital limb deficiencies (six types), negative controls (matched for age, sex, and place of residence), and positive controls (cases of sentinel anomalies). SETTING--The database of the Hungarian Congenital Abnormality Registry, 1975-84, complemented by three other sources of ascertainment (1,575,904 births). SUBJECTS--537 case-control pairs; 392 positive controls. MAIN OUTCOME MEASURES--Smoking during pregnancy, congenital limb deficiencies. RESULTS--The adjusted rate of smoking during pregnancy was significantly higher in the mothers of cases of terminal transverse defect (relative odds 1.48; 95% confidence interval 0.98 to 2.23; P = 0.017). This finding supports the hypothesis of vascular disruption as a cause of congenital limb deficiency. CONCLUSIONS--Maternal smoking during pregnancy raises the relative odds for terminal transverse limb deficiencies.     

Congenital abnormalities and indicators of germinal mutations in the vicinity of an acrylonitrile producing factory.

The results of an environmental mutation and teratologic epidemiological study are presented which was performed in inhabitants living in the surrounding region of an acrylonitrile factory in Nyergesújfalu. The endpoint of the study was congenital abnormalities in 46,326 infants born to mothers living in the 30 settlements of the study region within a 25 km radius of the acrylonitrile factory between 1980 and 1996. The ascertainment of cases with congenital abnormalities was based on the dataset of the Hungarian Congenital Abnormality Registry complemented with the review of pediatric, pathology and cytogenetic records. A particular attention was paid to the indicators of germinal mutations as sentinel anomalies, Down syndrome and unidentified multiple congenital abnormalities and the indicators of teratogens as the specific pattern of multiple congenital abnormalities. Three congenital abnormalities: pectus excavatum in Tata, 1990-1992 (OR with 95%CI: 78.5, 8.4-729.6), undescended testis in Nyergesújfalu between 1980 and 1983 (8.6, 1.4-54.3) and in Esztergom, 1981-1982 (4. 2, 1.3-13.5) and clubfoot in Tata, 1980-1981 (5.5, 1.5-20.3) showed significant time-space clusters in the study region. There was a decrease in risk of undescended testis with increasing distance from the acrylonitrile factory. An unusual increase was found in the combination of oral cleft and cardiac septal defects in multimalformed babies in Tatabánya, 1990. The detailed analysis of congenital abnormalities in all settlements of a given territory may help to detect clusters of congenital abnormalities and their possible relation to the environmental hazards.     

International Commission for Protection Against Environmental Mutagens and Carcinogens. ICPEMC working paper no. 4. Mutation surveillance of sentinel anomalies in Hungary, 1980-1984

Sentinel phenotypes are indicators of germinal dominant gene mutations. 23 sentinel abnormalities and 2 sentinel childhood tumours (bilateral retinoblastoma and Wilms' tumour), i.e., 25 sentinel anomalies of autosomal dominant origin were selected from the material of the Hungarian Congenital Malformation Registry, 1980-1984. Furthermore, cases of sentinel childhood tumours from the Hungarian Childhood Tumour Registry and some extra notifications of sentinel abnormalities were also included. Experts examined index patients and their parents in order to confirm or exclude nosological diagnosis, to separate sporadic and familial cases, to obtain environmental history and to give genetic counselling. The revised total observed prevalence of 25 sentinel anomalies was 3.80 per 10,000 livebirths. Only 12% of cases examined were familial. According to the statistical power calculation, 47,500 livebirths are needed to detect a doubling of mutation rate with probabilities of type I and II errors of 0.05 level. In Hungary the average number of yearly births was 135,548 in the study period.     

Maternal factors in the origin of isolated oesophageal atresia: A population‐based case–control study

Background: In most patients affected by isolated oesophageal atresia (IOA) the etiology is largely unknown. Thus, the aim of this study was to analyze potential risk factors in mothers. Methods: The study samples included 221 cases with IOA, 356 matched and 38,151 population controls without any defect in the population‐based dataset of the Hungarian Case–Control Surveillance of Congenital Abnormalities, 1980 to 1996. Only those exposures were evaluated that were medically recorded in prenatal maternity logbooks during the critical period of IOA. Results: The findings of this case–control study suggested that the mothers of cases with IOA had a higher proportion of first delivery and lower socioeconomic status. Acute respiratory diseases (odds ratio [OR] 95% confidence interval [CI], 3.8, 1.8–8.1) and essential hypertension treated with nifedipine (OR 95% CI, 3.8, 1.7–8.7) in the mothers of cases associated with a higher risk for IOA in their children. Conclusion: First delivery, lower socioeconomic status, acute respiratory diseases and essential hypertension treated with nifedipine in the mothers may associate with a higher risk for IOA in their children. Birth Defects Research (Part A) 103:804–813, 2015. © 2015 Wiley Periodicals, Inc.     

Paper 1: The EUROCAT network--organization and processes

The European Surveillance of Congenital Anomalies (EUROCAT) is a network of population-based congenital anomaly registries in Europe, funded by the European Union, which has been in operation for more than 30 years. It currently surveys more than 1.7 million births per year, including 31% of births in the European Union, and includes almost all population-based European congenital anomaly registries as its members. EUROCAT member registries collect data, ascertained from multiple sources, on all major structural congenital and chromosomal anomalies. EUROCAT surveillance relates to three areas: prevalence, primary prevention, and prenatal screening. This article describes the history of EUROCAT and gives an overview of the current methodology and work of EUROCAT covering the database content and management, coding and classification of anomalies, core surveillance, prevalence tables, statistical monitoring. The monitoring of new developments in prenatal diagnosis, medication during pregnancy, use of folic acid, and investigation of clusters and exposures are overseen by working groups responsible for organizing research and producing regular reports. The EUROCAT Web site includes current data on prevalence rates and prenatal detection rates-an example of information useful to clinicians, public health service managers, and patients.     

Rates of mutant structural chromosome rearrangements in human fetuses: data from prenatal cytogenetic studies and associations with maternal age and parental mutagen exposure.

In 27,225 prenatal cytogenetic studies of amniotic fluid reported to the New York State Chromosome Registry and the United States Interregional Chromosome Register System, there were 61 cases with a structural chromosomal abnormality not known inherited, a rate per 1,000 of 2.24. Of these 33, 1.21 per 1,000 were known de novo and nonmosaic; consequently, the rate of events resulting from germinal mutation is highly likely to be between these two limits. The rates per 1,000 of unbalanced abnormalities were 0.59-1.29; of balanced abnormalities, 0.62-0.96; of balanced Robertsonian translocations, 0.22-0.29; and of unbalanced Robertsonian translocations, 0.07-0.11. The rates of fetuses with supernumerary markers and fragments were unexpectedly high: 0.26-0.70 per 1,000. These abnormalities were associated with increased maternal age (38.0 +/- 5.4 to 38.4 +/- 3.6 compared to 35.6 +/- 4.3 in controls), but even after adjustment for the bias to preferential study of older women, the observed rates of these supernumerary abnormalities were greater than would be expected from live-birth studies or rates estimated in all recognized conceptuses. There were trends to elevated maternal age for the group of all balanced rearrangements, and to diminished maternal age for the nonsupernumerary, non-Robertsonian unbalanced rearrangements. In 136 women studied primarily because of exposure to a putative mutagen, a de novo deletion and an inversion not known inherited were detected. The rate of abnormality in these 136, 1.47%, was significantly greater than the rate of abnormality in the remainder: 0.14%-0.22%.     

Ascertainment of pregnancies terminated because of birth defects: effect on completeness of adding a new source of data

BACKGROUND: When evaluating preventive programs such as folate promotion and rubella vaccination, it is critically important to include terminations of pregnancy for neural tube defects and congenital rubella syndrome. Data from birth defects registries are often used for this purpose. The Western Australian Birth Defects Registry ascertains cases of birth defects in livebirths, stillbirths, and terminations of pregnancy for fetal abnormality, using multiple sources of ascertainment. METHODS: Data on terminations of pregnancy for fetal abnormality from the Western Australian Hospital Morbidity Data System 1980-1997 (not previously available to the Registry) were used to estimate the completeness of ascertainment of such cases by the Registry. Ascertainment-adjusted prevalences were calculated using capture-recapture methods. RESULTS: A total of 702 terminations with birth defects were identified among hospital discharges, most of which were already known to the Registry (87.9%). Of the 85 new cases, seven had a neural tube defect, 23 had a chromosomal defect, and 12 had confirmed maternal rubella infection during pregnancy. The ascertainment-adjusted prevalence was not importantly [corrected] different for birth defects overall or for these individual conditions, although the 95% confidence intervals for all birth defects, and for all chromosomal defects, did not include the prevalence based on registered cases only. CONCLUSIONS: The Western Australian Birth Defects Registry ascertains a high proportion of pregnancies terminated for fetal abnormality, and should therefore be a reliable source of data with which to assist in monitoring the effectiveness of preventive programs.