50 years of the Hungarian Congenital Abnormality Registry

The Population-Based Hungarian Twin Registry: An Update

Between 2006 and 2021, the Hungarian Twin Registry (HTR) operated a volunteer twin registry of all age groups (50% monozygotic [MZ], 50% dizygotic [DZ], 70% female, average age 34 ± 22 years), including 1044 twin pairs, 24 triplets and one quadruplet set. In 2021, the HTR transformed from a volunteer registry into a population-based one, and it was established in the Medical Imaging Centre of Semmelweis University in Budapest. Semmelweis University's innovation fund supported the development of information technology, a phone bank and voicemail infrastructure, administrative materials, and a new website was established where twins and their relatives (parent, foster parent or caregiver) can register. The HTR's biobank was also established: 157,751 individuals with a likely twin-sibling living in Hungary (77,042 twins, 1194 triplets, 20 quadruplets, and one quintuplet) were contacted between February and March of 2021 via sealed letters. Until November 20, 2022, 12,001 twin individuals and their parents or guardians (6724 adult twins, 3009 parents/guardians and 5277 minor twins) registered, mostly online. Based on simple self-reports, 37.6% of the registered adults were MZ twins and 56.8% were DZ; 1.12% were triplets and 4.5% were unidentified. Of the registered children, 22.3% were MZ, 72.7% were DZ, 1.93% were triplets, and 3.05% were unidentified. Of the registered twins, 59.9% were female (including both the adult and minor twins). The registration questionnaire consists of eight parts, including socio-demographic and anthropometric data, smoking habits and medical questions (diseases, operations, therapies). Hungary's twin registry has become the sole and largest population-based twin registry in Central Eastern Europe. This new resource will facilitate performing world-class modern genetic research.

Reducing the Risk of Birth Defects Associated with Maternal Influenza: Insights from a Hungarian Case-Control Study

Influenza viruses can cause several complications during pregnancy. Therefore, we aimed to investigate the effects of influenza on the development of congenital abnormalities (CAs) by analyzing the database of the Hungarian Case-Control Surveillance of Congenital Abnormalities (HCCSCA). In our multicenter, case-control, population-based study, we processed clinician-reported outcomes and diagnoses collected in the HCCSCA. The case group included newborns with different non-chromosomal birth defects, while the controls were newborns without CAs. Maternal influenza, as a risk factor for CAs, was analyzed by using a logistic regression model and odds ratios with 95% confidence intervals (CIs). Our results showed that maternal influenza in the first trimester was associated with increased odds of developing non-chromosomal CAs (OR: 1.41, CI: 1.28-1.55). There were increased odds of neural tube defects (OR: 2.22, CI: 1.78-2.76), orofacial clefts (OR: 2.28, CI: 1.87-2.78), and congenital heart defects (OR: 1.28, CI: 1.10-1.49) after influenza infection. In all cases, we found a protective effect of folic acid supplementation in the first trimester. In summary, the odds of non-chromosomal birth defects are higher after maternal influenza in the first trimester, and folic acid or pregnancy vitamin supplementation and antipyretic therapy may reduce the effect of maternal influenza during the first trimester.

The importance of pharmacoepidemiology in pregnancy-implications for safety

INTRODUCTION

Prescription of medications to pregnant women is usually a challenge as the drug benefit has to be considered regarding its potential adverse effects. As medication use is common in pregnant women, by chance or necessity, it gives the opportunity to evaluate the consequences of prenatal drug exposure in real life through pharmacoepidemiologic studies. Area covered: Data sources are numerous. Some of them have been created for the particular purpose of assessing medications during pregnancy. Augmented databases enable the study of delayed effects in late childhood and provide information on potential confounders. Each data source exhibits strengths and weaknesses. Several designs can be used to assess the safety of medications during pregnancy. Innovative designs have been developed in order to bypass major limits of classical methods. Expert opinion: An efficient system could follow up each pregnant woman, who had taken a medication, and consider her as a precious information for the knowledge of drug potential adverse actions against the child, who must be followed up to identify long term-effects. The diversity of data sources and approaches of pharmacoepidemiologic studies, the implementation of international networks as well as the improvement of adverse signal detection are the keystones of such an evaluation.

Maternal factors in the origin of infantile hypertrophic pyloric stenosis: A population-based case-control study

In most patients affected by isolated infantile hypertrophic pyloric stenosis (IHPS) the etiology is largely unknown. Thus, the aim of this study was to estimate possible maternal risk factors in the origin of IHPS. The study samples included 241 cases with IHPS, 357 matched controls and 38,151 population controls without any defect in the population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996. Exposures that had been medically recorded in prenatal maternity logbooks during the critical period of IHPS were evaluated separately. The findings of this case-control study suggested that--beyond the well-known robust male excess (85.5%)--maternal hyperthyroidism (OR with 95% CI: 4.17, 1.53-11.38) and oral nalidixic acid treatment (OR with 95% CI: 6.53, 3.03-14.06) associated with a higher risk for IHPS in their children. In conclusion, our findings suggest that cases with IHPS had mothers with a higher proportion of hyperthyroidism and nalidixic acid treatment during pregnancy.

Birth outcomes of patients with isolated anorectal malformations: A population-based case-control study

In most patients affected by isolated anorectal malformation (IARM) the etiology is largely unknown. Thus, the aim of our project was to analyze possible risk factors for IARM. In the first step, birth outcomes of cases with IARM were analyzed on the basis of maternal socio-demographic variables, and these data are presented in this paper. Gestational age at delivery, birthweight, preterm birth, low birthweight and small for gestational age of cases with IARM were evaluated in the function of maternal age, birth/pregnancy order, marital and employment status of mothers in the population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996. The study samples included 231 live-born cases with IARM, 361 matched and 38 151 population controls without any defect. IARMs are more frequent in males, twins and newborn infants with low birthweight and small-for-gestational-age, the latter being the consequence of intrauterine growth restriction. In addition, mothers of cases were younger but with higher birth order, and had lower socio-economic status. These maternal variables are characteristic for the gypsy population in Hungary. The higher proportion of gypsy women among the mothers of cases with IARM was confirmed during the home visits of the study. Male sex and intrauterine growth restriction of cases, in addition to low socioeconomic status and gypsy origin of mothers may have a role in the risk of IARMs.

Maternal factors in the origin of isolated anorectal malformations - a population-based case-control study

OBJECTIVE

In most patients affected by isolated anorectal malformation (IARM), the etiology is unknown. Thus, the aim of this study was to analyze the possible role of maternal risk factors in the origin of IARM.

METHODS

The study samples included 231 cases with IARM, 361 matched and 38 151 population controls without any defect in the population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996. Cases with IARM were evaluated in the function of maternal diseases and related drug use.

RESULTS

The findings of this case-control study suggested that cases with IARM have an obvious male excess. The mothers of cases with IARM had a lower incidence of severe nausea and vomiting in pregnancy and a higher incidence of acute infectious diseases in the urinary tract.

CONCLUSIONS

Lack of nausea and vomiting in pregnancy and the higher incidence of urinary tract infections may have a role in the development of IARM.

No increases in the rate of undescended testis in Hungary during the last 50 years: A population-based study

Undescended testis (cryptorchidism) is a common structural birth defect, i.e. congenital abnormality of the male genital organs and increasing trend in its birth prevalence was reported in some countries. The aim of this study was to analyze the recorded annual birth prevalence of isolated undescended testis (IUT) in the population-based large dataset of the Hungarian Congenital Abnormality Registry for the period between 1962 and 2011, i.e. during the last 50 years. Cases with IUT reported after births were evaluated, and their annual rate per 1000 live-births was calculated. The rates of cases with IUT were compared with the so-called true rate of IUT measured in a previous clinical-epidemiological study based on the personal examination of 10,203 newborn infants. The birth prevalence of cases with recorded IUT in Hungary was lower than expected based on the true rate of IUT. Thus the two waves in the rate of IUT were connected with the different completeness of reporting. In conclusion the birth prevalence of cases with IUT in Hungary did not indicate a real increasing trend during the last 50 years.

Birth outcomes of male and female patients with infantile hypertrophic pyloric stenosis--a population-based case-control study

OBJECTIVE

Most of the patients are affected by isolated infantile hypertrophic pyloric stenosis (IHPS) beyond the polygenic predisposition, the other factors in the multifactorial etiology are largely unknown. The main characteristic of IHPS is the robust male predominance, thus the aim of this study was to analyze birth outcomes in males and females whether they are different or not.

METHODS

The study samples included 241 cases with IHPS, 357 matched, and 38,151 population controls without any defect in the population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996.

RESULTS

The findings of this case-control study confirmed the well-known strong male excess (85.5%). The mean gestational age was somewhat longer and it is associated with a lower rate of preterm births. Mean birth weight did not show significant differences among the study groups, but the rate of low birthweight was higher in cases with IHPS. However, these differences were found only in males. Thus, intrauterine fetal growth restriction is characteristic only for male cases with IHPS.

CONCLUSIONS

Our study confirmed the well-known obvious male excess of cases with IHPS, but our findings suggest some differences in birth outcomes of male and female cases. Male cases with IHPS had intrauterine fetal growth restriction while females did not. These data may indicate some differences in the pathogenesis of IHPS in males and females.

Sex ratio of congenital abnormalities in the function of maternal age: a population-based study

Maternal age effect is well-known in the origin of numerical chromosomal aberrations and some isolated congenital abnormalities (CAs). The sex ratio (SR), i.e. number of males divided by the number of males and females together, of most CAs deviates from the SR of newborn population (0.51). The objective of this analysis was to evaluate the possible association of maternal age with the SR of isolated CAs in a population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996. First, SR of 24 CA entities/groups was estimated in 21,494 patients with isolated CA. In the next step SR of different maternal age groups was compared to the mean SR of the given CA-groups. The SR of four CA-groups showed some deviation in certain maternal age groups. Cases with anencephaly had female excess in young mothers (<25 years). Cases with skull's CAs particularly craniosynostosis had a male excess in cases born to women over 30 years. Two other CA groups (cleft lip ± palate and valvar pulmonic stenosis within the group of right-sided obstructive defect of heart) had significant deviation in SR of certain maternal age groups from the mean SR, but these deviations were not harmonized with joining age groups and thus were considered as a chance effect due to multiple testing. In conclusion, our study did not suggest that in general SR of isolated CAs might be modified by certain maternal age groups with some exception such as anencephaly and craniosynostosis.

Higher risk of orofacial clefts in children born to mothers with angina pectoris: a population-based case-control study

Previously an unexpected association of maternal angina pectoris (MAP) during pregnancy with a higher risk of orofacial clefts in their children was found. There were three objectives of this study: (i) to evaluate the validity of MAP-diagnoses in the previous study and the recent history of mothers with MAP in a follow-up study; (ii) to estimate the prevalence of other congenital abnormalities in the offspring of mothers with MAP; and (iii) to analyze the possible effect of confounders for the risk of orofacial clefts. The large dataset of population-based Hungarian Case-Control Surveillance System of Congenital Abnormalities, 1980-1996 was evaluated including 22 843 cases with congenital abnormalities and 38 151 controls without any defect. Twenty-two cases (0.10%) and 12 controls (0.03%) were born to mothers with medically recorded MAP (odds ratio [OR] with 95% confidence interval [CI]: 3.7, 1.8-7.3). Of 22 cases, six had isolated cleft lip ± palate (OR with 95% CI: 13.3, 4.9-35.9) and two were affected with isolated cleft palate (OR with 95% CI: 10.5, 2.3-47.6). The diagnosis of MAP was confirmed in seven women visited at home in 2009-2010, two had recent myocardial infarction and five were smokers. There was no higher risk for other congenital abnormalities. In conclusion the higher risk of orofacial clefts was confirmed in the children of mothers with MAP and smoking may trigger the genetic predisposition of both MAP and orofacial clefts. However, the number of cases was limited and therefore further studies are needed to confirm or reject this theoretically and practically important observation.

Distribution of maternal age and birth order groups in cases with unclassified multiple congenital abnormalities according to the number of component abnormalities: a national population-based case-control study

BACKGROUND

Multiple congenital abnormalities are caused by chromosomal aberrations, mutant major genes and teratogens. A minor proportion of these patients are identified as syndromes but the major part belonging to the group of unclassified multiple CAs (UMCAs). The main objective of this study was to evaluate the maternal age and birth order in pregnant women who had offspring affected with UMCA. The strong association between numerical chromosomal aberrations, e.g., Down syndrome and advanced maternal age is well-known and tested here.

METHODS

The Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980 to 1996, yielded a large population-based national data set with 22,843 malformed newborns or fetuses ("informative cases") included 1349 UMCA cases with their 2407 matched controls. Case-control comparison of maternal age and birth order was made for cases with UMCA, stratified by component numbers and their controls. In addition, 834 cases with Down syndrome were compared to 1432 matched controls.

RESULTS

The well-known advanced maternal age with the higher risk for Down syndrome was confirmed. The findings of the study suggest that the young age of mothers associates with the higher risk of UMCA, in addition birth order 4 or more associates with the higher risk for UMCA with 2 and 3 component CAs.

CONCLUSION

This study was the first to analyze the possible maternal and birth order effect for cases with UMCA, and the young age and higher birth order associated with a higher risk for UMCA.

Association of certain chronic maternal diseases with the risk of specific congenital heart defects: a population-based study

OBJECTIVE

Previous epidemiological studies have evaluated cases with all congenital heart defects (CHDs), rather than analysing different types of CHD. The objective of this study was to evaluate the possible association of certain chronic maternal diseases with the risk of different types of CHD, because the role of possible environmental factors in the origin of CHDs is unclear in the vast majority of patients.

STUDY DESIGN

Different types of CHD, diagnosed after lethal outcome (autopsy report) or after surgical intervention (catheter or correction), were evaluated in order to estimate the possible role of chronic maternal diseases in their origin. This analysis was based on the rates of medically recorded chronic maternal diseases in 3562 live-born cases with CHDs, 38,151 population controls without any birth defects, and 16,602 malformed controls with other isolated congenital abnormalities, using the data set of the population-based Hungarian Case-Control Surveillance of Congenital Abnormalities (1980-1996).

RESULTS

Maternal epilepsy treated with carbamazepine and migraine were found to be associated with higher risk of ventricular septal defect; panic disorders were associated with higher risk of hypoplastic left heart; type I diabetes mellitus was associated with higher risk of coarctation of the aorta; chronic hypertension was associated with higher risk of ventricular septal defect, common atrioventricular canal and common truncus; and paroxysmal supraventricular tachycardia was associated with higher risk of atrial septal defect secundum, common atrioventricular canal and ventricular septal defect.

CONCLUSION

In conclusion, certain chronic maternal diseases were found to be associated with higher risk of specific CHDs. Appropriate treatment of these diseases may help to prevent these CHDs.

Possible association of maternal factors with the higher risk of isolated true undescended testis: A population-based case-control study

The objective of the study was to evaluate the possible association of maternal factors with the risk of isolated true undescended testis (ITUT) diagnosed at the third postnatal month because our knowledge is limited regarding the origin of ITUT. Acute and chronic diseases with related drug treatments were compared in the mothers of 2052 cases with ITUT, 24,814 male controls without any defects and 12,082 malformed male controls with other isolated defects in the population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996. Prospective medically recorded endometriosis before conception of the study pregnancy in the mothers of 39 cases was associated with a higher risk of ITUT in their sons (odds ratio (OR) with 95% confidence interval [CI]: 2.42, 1.71-3.42). Dihydrogesterone treatment in the first trimester of pregnancy also showed association with the higher risk of ITUT but based on only five pregnant women. In conclusion, endometriosis before pregnancy may have a role in the origin of ITUT.