Marian K. Bakker

Drug prescription patterns before, during and after pregnancy for chronic, occasional and pregnancy-related drugs in the Netherlands.

Objective  To compare the prescription of drugs in women over a period from 2 years before until 3 months after pregnancy, regarding the type of drugs used and the fetal risk.

Protective effect of periconceptional folic acid supplements on the risk of congenital heart defects: a registry-based case-control study in the northern Netherlands.

AIMS To investigate the potentially protective of periconceptional folic acid use on the risk of congenital heart defects (CHDs) relative to other non-folate related malformations. METHODS AND RESULTS We analysed data from a large regional register of birth defects (EUROCAT-Northern Netherlands), over a 10 year period (1996-2005) for a case-control study. The cases were mothers who had delivered infants with isolated or complex heart defects, without any related syndrome or genetic abnormality (n = 611). We used two control groups; one from the EUROCAT database and another from the general population. The registry controls consisted of mothers of children with a known chromosomal or genetic defect, and with infants with other non-folate related congenital malformations (n = 2401). Additional folic acid was taken as a single supplement or as a multivitamin containing folic acid in a dose of >or=400 microg daily. Mothers who had used folate antagonists or who had diabetes, and mothers of children with oral clefts, hypospadias, limb reduction- or neural tube defects, were excluded from both groups. Potentially confounding factors of periconceptional folic acid use in relation to CHD were explored, including babys birth year, maternal body mass index, education, maternal age at delivery of index baby, smoking behaviour, and alcohol use during pregnancy. Periconceptional folic acid use revealed an odds ratio (OR) of 0.82 (95% CI 0.68-0.98) for all types of CHD relative to other malformations. The estimated relative risk for CHDs of additional folic acid use compared with the general population was comparable [OR 0.74 (95%CI 0.62-0.88)]. Subgroup analysis showed an OR of 0.62 (95% CI 0.47-0.82) for isolated septal defects. The proportions of the potential confounders between mothers of case and control infants did not differ significantly. CONCLUSION Our results support the hypothesis that additional periconceptional folic acid use reduces CHD risk in infants. Use of periconceptional folic acid supplements was related to approximately 20% reduction in the prevalence of any CHD. Given the relatively high prevalence of CHD worldwide, our findings are important for public health.

International trends of Down syndrome 1993-2004: Births in relation to maternal age and terminations of pregnancies

BACKGROUND The aim of this study was to examine trends of Down syndrome (DS) in relation to maternal age and termination of pregnancies (ToP) in 20 registries of the International Clearinghouse for Birth Defects Surveillance and Research (ICBDSR). METHODS Trends of births with DS (live-born and stillborn), ToP with DS, and maternal age (percentage of mothers older than 35 years) were examined by year over a 12-year period (1993-2004). The total mean number of births covered was 1550,000 annually. RESULTS The mean percentage of mothers older than 35 years of age increased from 10.9% in 1993 to 18.8% in 2004. However, a variation among the different registers from 4-8% to 20-25% of mothers >35 years of age was found. The total mean prevalence of DS (still births, live births, and ToP) increased from 13.1 to 18.2/10,000 births between 1993 and 2004. The total mean prevalence of DS births remained stable at 8.3/10,000 births, balanced by a great increase of ToP. In the registers from France, Italy, and the Czech Republic, a decrease of DS births and a great increase of ToP was observed. The number of DS births remained high or even increased in Canada Alberta, and Norway during the study period. CONCLUSIONS Although an increase in older mothers was observed in most registers, the prevalence of DS births remained stable in most registers as a result of increasing use of prenatal diagnostic procedures and ToP with DS.

Paper 6: EUROCAT member registries: organization and activities

BACKGROUND EUROCAT is a network of population-based congenital anomaly registries providing standardized epidemiologic information on congenital anomalies in Europe. There are three types of EUROCAT membership: full, associate, or affiliate. Full member registries send individual records of all congenital anomalies covered by their region. Associate members transmit aggregate case counts for each EUROCAT anomaly subgroup by year and by type of birth. This article describes the organization and activities of each of the current 29 full member and 6 associate member registries of EUROCAT. METHODS Each registry description provides information on the history and funding of the registry, population coverage including any changes in coverage over time, sources for ascertaining cases of congenital anomalies, and upper age limit for registering cases of congenital anomalies. It also details the legal requirements relating to termination of pregnancy for fetal anomalies, the definition of stillbirths and fetal deaths, and the prenatal screening policy within the registry. Information on availability of exposure information and denominators is provided. The registry description describes how each registry conforms to the laws and guidelines regarding ethics, consent, and confidentiality issues within their own jurisdiction. Finally, information on electronic and web-based data capture, recent registry activities, and publications relating to congenital anomalies, along with the contact details of the registry leader, are provided. CONCLUSIONS The registry description gives a detailed account of the organizational and operational aspects of each registry and is an invaluable resource that aids interpretation and evaluation of registry prevalence data.

Rare chromosome abnormalities, prevalence and prenatal diagnosis rates from population-based congenital anomaly registers in Europe

The aim of this study is to quantify the prevalence and types of rare chromosome abnormalities (RCAs) in Europe for 2000–2006 inclusive, and to describe prenatal diagnosis rates and pregnancy outcome. Data held by the European Surveillance of Congenital Anomalies database were analysed on all the cases from 16 population-based registries in 11 European countries diagnosed prenatally or before 1 year of age, and delivered between 2000 and 2006. Cases were all unbalanced chromosome abnormalities and included live births, fetal deaths from 20 weeks gestation and terminations of pregnancy for fetal anomaly. There were 10 323 cases with a chromosome abnormality, giving a total birth prevalence rate of 43.8/10 000 births. Of these, 7335 cases had trisomy 21,18 or 13, giving individual prevalence rates of 23.0, 5.9 and 2.3/10 000 births, respectively (53, 13 and 5% of all reported chromosome errors, respectively). In all, 473 cases (5%) had a sex chromosome trisomy, and 778 (8%) had 45,X, giving prevalence rates of 2.0 and 3.3/10 000 births, respectively. There were 1 737 RCA cases (17%), giving a prevalence of 7.4/10 000 births. These included triploidy, other trisomies, marker chromosomes, unbalanced translocations, deletions and duplications. There was a wide variation between the registers in both the overall prenatal diagnosis rate of RCA, an average of 65% (range 5–92%) and the prevalence of RCA (range 2.4–12.9/10 000 births). In all, 49% were liveborn. The data provide the prevalence of families currently requiring specialised genetic counselling services in the perinatal period for these conditions and, for some, long-term care.

First-trimester use of paroxetine and congenital heart defects: A population-based case-control study†‡

BACKGROUND There is a need for case-control studies of the effect of paroxetine on the occurrence of specific heart defects. METHODS We performed a case-control study with data from a population-based birth defects registry in the Netherlands. All the children born between 1997 and 2006 were selected. Cases were defined as fetuses and children with isolated heart defects, and the controls were fetuses and children with a genetic disorder with no heart defect. We excluded children for whom there was no information on maternal medication use and deceased children and fetuses who were not examined postmortem. First-trimester exposure to paroxetine was compared between cases and controls by calculating adjusted odds ratios (AOR). RESULTS We included 678 cases with isolated heart defects and 615 controls. The first trimester exposure rate was 1.5% for cases and 1.0% for controls. After excluding mothers who used paroxetine outside the first trimester, or who had used another SSRI, we found no significantly increased risk for heart defects overall (10 exposed cases; AOR, 1.5; 95% confidence interval [CI], 0.5-4.0), but we did find a significantly increased risk for atrium septum defects (three exposed cases; AOR, 5.7; 95% CI, 1.4-23.7). CONCLUSIONS Our results suggest that the use of paroxetine in early pregnancy is associated with an increased risk of atrium septum defects. The results stress the importance of studying possible teratogenic effects of a drug, preferably in regard to well-specified malformations.

International Trends of Down Syndrome 1993-2004: Births in Relation to Maternal Age and Terminations of Pregnancies

BACKGROUND The aim of this study was to examine trends of Down syndrome (DS) in relation to maternal age and termination of pregnancies (ToP) in 20 registries of the International Clearinghouse for Birth Defects Surveillance and Research (ICBDSR). METHODS Trends of births with DS (live-born and stillborn), ToP with DS, and maternal age (percentage of mothers older than 35 years) were examined by year over a 12-year period (1993-2004). The total mean number of births covered was 1550,000 annually. RESULTS The mean percentage of mothers older than 35 years of age increased from 10.9% in 1993 to 18.8% in 2004. However, a variation among the different registers from 4-8% to 20-25% of mothers >35 years of age was found. The total mean prevalence of DS (still births, live births, and ToP) increased from 13.1 to 18.2/10,000 births between 1993 and 2004. The total mean prevalence of DS births remained stable at 8.3/10,000 births, balanced by a great increase of ToP. In the registers from France, Italy, and the Czech Republic, a decrease of DS births and a great increase of ToP was observed. The number of DS births remained high or even increased in Canada Alberta, and Norway during the study period. CONCLUSIONS Although an increase in older mothers was observed in most registers, the prevalence of DS births remained stable in most registers as a result of increasing use of prenatal diagnostic procedures and ToP with DS.

The role of maternal-fetal cholesterol transport in early fetal life: Current insights

ABSTRACT The importance of maternal cholesterol as an exogenous cholesterol source for the growing embryo was first reported in studies of Smith-Lemli-Opitz syndrome. Although most of the fetuss cholesterol is synthesized by the fetus itself, there is now growing evidence that during the first weeks of life, when most organs develop, the fetus largely depends on maternal cholesterol as its cholesterol source. The maternal-fetal cholesterol transport mechanism, by transporters in both the yolk sac and placenta, is becoming better understood. This minireview summarizes current insights on maternal-fetal cholesterol transport based on in vitro and in vivo studies. As the prevalence of maternal diseases, such as diabetes, obesity, and the metabolic syndrome that adversely affect maternal cholesterol levels, is now rapidly reaching epidemic proportions, we urgently need to determine the impact of these maternal conditions on the developing human fetus.

Frequency of holoprosencephaly in the International Clearinghouse Birth Defects Surveillance Systems: Searching for population variations

BACKGROUND Holoprosencephaly (HPE) is a developmental field defect of the brain that results in incomplete separation of the cerebral hemispheres that includes less severe phenotypes, such as arhinencephaly and single median maxillary central incisor. Information on the epidemiology of HPE is limited, both because few population-based studies have been reported, and because small studies must observe a greater number of years in order to accumulate sufficient numbers of births for a reliable estimate. METHODS We collected data from 2000 through 2004 from 24 of the 46 Birth Defects Registry Members of the International Clearinghouse for Birth Defects Surveillance and Research. This study is based on more than 7 million births in various areas from North and South America, Europe, and Australia. RESULTS A total of 963 HPE cases were registered, yielding an overall prevalence of 1.31 per 10,000 births. Because the estimate was heterogeneous, possible causes of variations among populations were analyzed: random variation, under-reporting and over-reporting bias, variation in proportion of termination of pregnancies among all registered cases and real differences among populations. CONCLUSIONS The data do not suggest large differences in total prevalence of HPE among the studied populations that would be useful to generate etiological hypotheses.

Spectrum of congenital anomalies in pregnancies with pregestational diabetes

BACKGROUND Maternal pregestational diabetes is a well-known risk factor for congenital anomalies. This study analyses the spectrum of congenital anomalies associated with maternal diabetes using data from a large European database for the population-based surveillance of congenital anomalies. METHODS Data from 18 population-based EUROCAT registries of congenital anomalies in 1990-2005. All malformed cases occurring to mothers with pregestational diabetes (diabetes cases) were compared to all malformed cases in the same registry areas to mothers without diabetes (non-diabetes cases). RESULTS There were 669 diabetes cases and 92,976 non diabetes cases. Odds ratios in diabetes pregnancies relative to non-diabetes pregnancies comparing each EUROCAT subgroup to all other non-chromosomal anomalies combined showed significantly increased odds ratios for neural tube defects (anencephaly and encephalocele, but not spina bifida) and several subgroups of congenital heart defects. Other subgroups with significantly increased odds ratios were anotia, omphalocele and bilateral renal agenesis. Frequency of hip dislocation was significantly lower among diabetes (odds ratio 0.15, 95% CI 0.05-0.39) than non-diabetes cases. Multiple congenital anomalies were present in 13.6 % of diabetes cases and 6.1 % of non-diabetes cases. The odds ratio for caudal regression sequence was very high (26.40,95% CI 8.98-77.64), but only 17% of all caudal regression cases resulted from a pregnancy with pregestational diabetes. CONCLUSIONS The increased risk of congenital anomalies in pregnancies with pregestational diabetes is related to specific non-chromosomal congenital anomalies and multiple congenital anomalies and not a general increased risk.