Potential association between infertility and spinal neural tube defects in offspring

Post-Conceptional Exposure to Clomiphene Citrate and Congenital Malformations: A Cohort Study

BACKGROUND

Clomiphene citrate is an ovulation inductor for which inadvertent post-conceptional exposures may occur in early pregnancy. In preclinical studies, post-conceptional exposures showed a teratogenic effect in different species. In humans, to date, little is known about the outcomes of inadvertently post-conceptionally exposed pregnancies.

OBJECTIVES

The objectives of our study were to assess the association between post-conceptional exposures to clomiphene citrate and major and minor congenital malformations in the offspring.

METHODS

A retrospective cohort study of prospectively ascertained cases was undertaken, based on clinical data from the Centre de Référence sur les Agents Tératogènes (CRAT), Paris, France. Women with post-conceptional exposure to clomiphene citrate (n = 309), and unexposed pregnant women (n = 1236, 1:4 ratio) with prospectively collected data, known pregnancy outcome and delivery date prior to 01/02/2022, were matched by calendar year. An adjudication committee classified major and minor congenital malformations according to the EUROCAT (European Registration of Congenital Anomalies and Twins) classification.

RESULTS

Among post-conceptional exposed women, no increased risk of major malformation was found (crude relative risk = 0.64, 95% confidence interval 0.19-2.15) as compared to unexposed women. Three major and ten minor congenital malformations were reported in the exposed group. An increased risk of minor malformations was found (crude relative risk = 4.05, 95% confidence interval 1.70-9.64) although there was no specific clinical pattern.

CONCLUSIONS

Post-conceptional exposure to clomiphene citrate was not associated with an increased risk of major congenital malformations. Given potential confounding and information biases, the results about minor malformations should be interpreted with caution as no specific clinical pattern was identified.

Clomiphene Citrate Administered in Periconception Phase Causes Fetal Loss and Developmental Impairment in Mice

Clomiphene citrate is a common treatment for ovulation induction in subfertile women, but its use is associated with elevated risk of adverse perinatal outcomes and birth defects. To investigate the biological plausibility of a causal relationship, this study investigated the consequences in mice for fetal development and pregnancy outcome of periconception clomiphene citrate administration at doses approximating human exposures. A dose-dependent adverse effect of clomiphene citrate given twice in the 36 hours after mating was seen, with a moderate dose of 0.75 mg/kg sufficient to cause altered reproductive outcomes in 3 independent cohorts. Viable pregnancy was reduced by 30%, late gestation fetal weight was reduced by 16%, and ∼30% of fetuses exhibited delayed development and/or congenital abnormalities not seen in control dams, including defects of the lung, kidney, liver, eye, skin, limbs, and umbilicus. Clomiphene citrate also caused a 30-hour average delay in time of birth, and elevated rate of pup death in the early postnatal phase. In surviving offspring, growth trajectory tracking and body morphometry analysis at 20 weeks of age showed postweaning growth and development similar to controls. A dysregulated inflammatory response in the endometrium was observed and may contribute to the underlying pathophysiological mechanism. These results demonstrate that in utero exposure to clomiphene citrate during early pregnancy can compromise implantation and impact fetal growth and development, causing adverse perinatal outcomes. The findings raise the prospect of similar iatrogenic effects in women where clomiphene citrate may be present in the periconception phase unless its use is well-supervised.

Safety assessment of clomiphene: a real-world pharmacovigilance analysis from the Food and Drug Administration adverse event reporting system

BACKGROUND

Clomiphene is widely used for the treatment of anovulatory infertility, yet there remain many unrecognized adverse events (AEs). The objective of this study is to provide a comprehensive overview of the safety profile of clomiphene.

METHODS

The data were derived from the first quarter of 2004 to the third quarter of 2023 from the Food and Drug Administration Adverse Event Reporting System (FAERS) database. The detection of new AE signals involved the use of four algorithms: reporting odds ratio (ROR), proportional reporting ratio (PRR), Bayesian confidence propagation neural network (BCPNN), and empirical Bayesian geometric mean (EBGM).

RESULTS

A total of 16,677,289 AE reports were acquired from the FAERS database, and there were 2,620 AEs specifically reported in 720 patients following clomiphene use. The AEs encompassed 102 preferred terms (PTs) across 24 system organ classes (SOCs). Some new AEs were identified, including conjoined twins (0.5%), Potter's syndrome (0.3%), genitalia external ambiguous (0.3%), esophageal atresia (0.6%), and anal atresia (0.3%).

CONCLUSIONS

Although the majority of AEs aligned with the drug instruction, some new AE signals such as conjoined twins and genitalia external ambiguous were not captured. Well-designed studies are required to demonstrate the safety of clomiphene.

Risk factors associated with congenital central nervous system abnormalities in the National Hospital of Zinder, Niger

INTRODUCTION

Congenital malformations of the central nervous system (CNS) are morphological abnormalities of the brain and spinal cord that occur during fetal development. They constitute the second most common congenital disability, after congenital cardiac defects. Many risk factors have been identified; however, these studies included various types of congenital abnormality. Furthermore, there is a lack of information on risk factors for congenital CNS malformation, and notably in the Zinder region of Niger.

OBJECTIVE

This study aimed to identify the risk factors associated with congenital CNS malformations in the Zinder region.

METHODS

In a case-control design, patients with congenital CNS malformation were enrolled between June 2022 and April 2023 in the Department of Neurosurgery of the National Hospital of Zinder.

RESULTS

Family history of malformation (aOR:3.31, 95% CI:1.25-8.78) and consanguine marriage (aOR:2.28, 95% CI:1.23-4.20) were significantly associated with congenital CNS malformation. In contrast, folic acid supplementation (aOR:0.34, 95% CI:0.13, 0.89), multiparity (aOR:0.34, 95% CI:0.13, 0.89), and grand multiparity (aOR, 0.47; 95% CI:0.23, 0.97) had a protective effect.

CONCLUSION

Risk factors such as family malformation history and consanguine marriage increased the risk of developing congenital malformations of the central nervous system. In contrast, folic acid supplementation in the index period and multiparity had a significant protective effect.

Emulating a target trial of the comparative effectiveness of clomiphene citrate and letrozole for ovulation induction

STUDY QUESTION

What are the comparative pregnancy outcomes in women who receive up to six consecutive cycles of ovulation induction with letrozole versus clomiphene citrate?

SUMMARY ANSWER

The risks of pregnancy, livebirth, multiple gestation, preterm birth, neonatal intensive care unit (NICU) admission and congenital malformations were higher for letrozole compared with clomiphene in participants with polycystic ovarian syndrome (PCOS), though no treatment differences were observed in those with unexplained infertility.

WHAT IS KNOWN ALREADY

Randomized trials have reported higher pregnancy and livebirth rates for letrozole versus clomiphene among individuals with PCOS, but no differences among those with unexplained infertility. None of these trials were designed to study maternal or neonatal complications.

STUDY DESIGN, SIZE, DURATION

We emulated a hypothetical trial of the comparative effectiveness of letrozole versus clomiphene citrate for ovulation induction among all women, then stratified by PCOS and unexplained infertility status. We used real-world data from a large healthcare claims database in the USA (2011-2015).

PARTICIPANTS/MATERIALS, SETTING, METHODS

We analyzed data from 18 120 women who initiated letrozole and 49 647 women who initiated clomiphene during 2011-2014, and who were aged 18-45 years with no history of diabetes, thyroid disease, liver disease or breast cancer and had no fertility treatments for 3 months before trial initiation. The treatment strategies were clomiphene citrate or letrozole for six consecutive cycles. The outcomes were pregnancy, livebirth, multiple gestation, preterm birth, small for gestational age (SGA), NICU admission and major congenital malformations. We estimated the probability of each outcome under each strategy via pooled logistic regression and used standardization to adjust for confounding and selection bias due to loss to follow-up.

MAIN RESULTS AND THE ROLE OF CHANCE

The estimated probabilities of pregnancy, livebirth and neonatal outcomes were similar under each strategy, both overall and among individuals with unexplained infertility. Among women with PCOS, the probability of pregnancy was 43% for letrozole vs 37% for clomiphene (risk difference [RD] = 6.0%; 95% CI: 4.4, 7.7) in the intention-to-treat analyses. The corresponding probability of livebirth was 32% vs 29% (RD = 3.1%; 95% CI: 1.5, 4.8). In per protocol analyses, the risk of multiple gestation was 19% vs 9%, the risk of preterm birth was 20% vs 15%, the risk of SGA was 5% vs 3%, the risk of NICU admission was 22% vs 16% and the risk of congenital malformation was 8% vs 2% among those with a livebirth.

LIMITATIONS, REASONS FOR CAUTION

We cannot completely rule out the possibility of residual confounding by body mass index or duration of infertility. However, we adjusted for proxies identified in administrative data and results did not change.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings suggest that for women with unexplained infertility, the two treatments result in comparable probabilities of a livebirth. For women with PCOS, letrozole appears slightly more effective for attaining a livebirth. Neonatal outcomes were similar for the two treatments among women with unexplained infertility; we did not confirm the hypothesized higher risk of adverse neonatal outcomes for clomiphene versus letrozole. The risks of adverse neonatal outcomes were slightly greater among women with PCOS who were treated with letrozole versus clomiphene. It is likely that these effects are partially mediated through an increased risk of multiple gestation among women who received letrozole.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Institute of Child Health and Human Development (R01HD088393). Y.-H.C. reports grants from the American Heart Association (834106) and NIH (R01HD097778). P.R. reports grants from the National Institutes of Health. J.H. reports grants from the National Institutes of Health, the Agency for Healthcare Research and Quality, and the California Health Care Foundation during the conduct of the study; and consulting for several health care delivery organizations including Cambridge Health Alliance, Columbia University, University of Southern California, Community Servings, and the Delta Health Alliance. S.H.-D. reports grants from the National Institutes of Health and the US Food and Drug Administration during the conduct of the study; grants to her institution from Takeda outside the submitted work; consulting for UCB (biopharmaceutical company) and Roche; and being an adviser for the Antipsychotics Pregnancy Registry and epidemiologist for the North American Antiepileptics Pregnancy Registry, both at Massachusetts General Hospital. M.A.H. reports grants from the National Institutes of Health and the U.S. Veterans Administration during the conduct of the study; being a consultant for Cytel; and being an adviser for ProPublica.

TRIAL REGISTRATION NUMBER

N/A.

The Risk of Congenital Anomalies by Fertility Treatment Modality

Importance

Up to 4% of all births in developed nations involve assisted reproductive technology (ART), along with other fertility treatment modalities. Thus, ART pregnancies constitute an important epidemiologic population with a known increased risk of congenital anomalies. In this review, we summarize current fertility treatment modalities and their associated risk of congenital anomalies.

Objective

To review the risk of birth defects among pregnancies conceived with ART and other fertility treatments.

Evidence Acquisition

Articles were obtained from PubMed and the American College of Obstetricians and Gynecologists and American Society of Reproductive Medicine committee opinions.

Results

In vitro fertilization has been associated with a 25% to 50% increased risk of birth defects, including abnormalities of these organ systems: cardiovascular (25%-40% of anomalies), genitourinary (10%-60%), gastrointestinal (10%-20%), and musculoskeletal (10%-35%). Although the data are mixed, intracytoplasmic sperm injection has also been found to be associated with an increased risk of defects, particularly hypospadias, when compared with conventional in vitro fertilization. The risk among fresh versus frozen cycles and cleavage stage versus blastocyst transfers remains uncertain. There appears to be no significant added risk with preimplantation genetic testing, although more studies are needed. Ovulation induction with oral agents appears safe and not associated with an increased risk of anomalies. Oocyte cryopreservation also appears safe, but the data are still limited, requiring future investigation.

Conclusions and Relevance

While the relative risk of birth defects among ART pregnancies is increased when compared with spontaneous conceptions, the absolute risk remains low. There are no standard screening recommendations for ART pregnancies. Per the American College of Obstetricians and Gynecologists, patients who have undergone ART should be counseled regarding the risk of birth defects and available antenatal evaluation, including fetal echocardiogram and detailed ultrasound evaluation.

Fetal safety of medications used in treating infertility

INTRODUCTION

The medications used in assisted reproduction are given before and during early pregnancy, and hence, they may potentially result in adverse fetal effects. In this review we present an updated account of their fetal safety and discuss methodological challenges in interpretation of existing data.

AREAS COVERED

The fetal safety/risks of clomiphene citrate, aromatase inhibitors, metformin, gonadotropins and progestins are discussed. We searched PubMed, EMBASE, Cochrane, Google, and Google Scholar from inception to 30 April 2020 for publications pertinent to our topic.

EXPERT OPINION

There are several major challenges in studying fetal safety of medications used in assisted reproduction. The fact is that the rates of congenital malformations among infertile women giving birth spontaneously is higher than the rates among healthy women conceiving spontaneously. In most clinical studies of assisted reproduction, the primary endpoint is the success in inducing pregnancy, neglecting to report pregnancy outcome and adverse neonatal event. As an example for this reality, it has been estimated that between 1977 and 2005 around 10 million pregnancies were treated with dydrogesterone (DYD), yet till 2019 only very few studies, with a total sample size of less than 600 were reported with regards to fetal safety.

Potential Teratogenic Effects of Clomiphene Citrate

Clomiphene citrate (CC) is the oldest drug used to regulate the process of ovulation. Considering the great use of CC over the last 40 years, it is important to understand the possible risks associated with its use. The aim of this review was to evaluate the possible teratogenic effects of CC, analyzing results obtained from animal and human studies. The pharmacokinetics of CC and possible mechanisms involved in teratogenesis are examined. Fetal exposure to CC is possible due to the long half-life of CC and its metabolites. Alarming data have emerged from animal studies, although controversial results come from human studies. There is some evidence regarding a possible association of CC exposure and fetal malformations, mainly neural tube defects and hypospadias, which would require further investigation in order to allow safer use of this useful drug.

Obstetric and perinatal outcomes in subfertile patients who conceived following low technology interventions for fertility enhancement: a comprehensive review

PURPOSE

Low technology interventions for fertility enhancement (LTIFE) are strategies that avoid retrieval, handling, and manipulation of female gametes. The definition of LTIFE is yet to be widely accepted and clarified, but they are commonly used in milder cases of infertility and subfertility. Based on these considerations, the aim of the present study was comprehensively to review and investigate the obstetric and perinatal outcomes in subfertile patients who underwent LTIFE.

METHODS

A literature search up to May 2017 was performed in IBSS, SocINDEX, Institute for Scientific Information, PubMed, Web of Science, and Google Scholar. An evidence-based hierarchy was used according to The Oxford Centre for Evidence-Based Medicine to determine which articles to include and analyze, and to provide a level of evidence of each association between intervention and outcome.

RESULTS

This analysis identified preliminary and low-grade evidence on the influence of LTIFE on obstetric and perinatal outcomes in subfertile women.

CONCLUSIONS

LTIFE women should deserve major consideration from Clinicians/Researchers of Reproductive Medicine, because these treatments could be potentially responsible for mothers' and babies' complications. So far, the lack of well-designed and unbiased studies makes further conclusions difficult to be drawn.

EUROmediCAT signal detection: an evaluation of selected congenital anomaly-medication associations

AIMS

To evaluate congenital anomaly (CA)-medication exposure associations produced by the new EUROmediCAT signal detection system and determine which require further investigation.

METHODS

Data from 15 EUROCAT registries (1995-2011) with medication exposures at the chemical substance (5th level of Anatomic Therapeutic Chemical classification) and chemical subgroup (4th level) were analysed using a 50% false detection rate. After excluding antiepileptics, antidiabetics, antiasthmatics and SSRIs/psycholeptics already under investigation, 27 associations were evaluated. If evidence for a signal persisted after data validation, a literature review was conducted for prior evidence of human teratogenicity.

RESULTS

Thirteen out of 27 CA-medication exposure signals, based on 389 exposed cases, passed data validation. There was some prior evidence in the literature to support six signals (gastroschisis and levonorgestrel/ethinylestradiol (OR 4.10, 95% CI 1.70-8.53; congenital heart disease/pulmonary valve stenosis and nucleoside/tide reverse transcriptase inhibitors (OR 5.01, 95% CI 1.99-14.20/OR 28.20, 95% CI 4.63-122.24); complete absence of a limb and pregnen (4) derivatives (OR 6.60, 95% CI 1.70-22.93); hypospadias and pregnadien derivatives (OR 1.40, 95% CI 1.10-1.76); hypospadias and synthetic ovulation stimulants (OR 1.89, 95% CI 1.28-2.70). Antipropulsives produced a signal for syndactyly while the literature revealed a signal for hypospadias. There was no prior evidence to support the remaining six signals involving the ordinary salt combinations, propulsives, bulk-forming laxatives, hydrazinophthalazine derivatives, gonadotropin releasing hormone analogues and selective serotonin agonists.

CONCLUSION

Signals which strengthened prior evidence should be prioritized for further investigation, and independent evidence sought to confirm the remaining signals. Some chance associations are expected and confounding by indication is possible.

Association of Clomiphene and Assisted Reproductive Technologies With the Risk of Neural Tube Defects

Clomiphene and assisted reproductive technologies (ART) are methods used to help subfertile couples become pregnant. ART has been reported to be associated with neural tube defects (NTDs) in offspring. To evaluate these associations, we studied mothers of 219 cases and 4,262 controls from the Slone Epidemiology Center Birth Defects Study (1993-2012) who were interviewed within 6 months after delivery about pregnancy events, including use of fertility treatments. We considered exposures to clomiphene (without ART) and ART during the periconceptional period. Logistic regression models were used to calculate adjusted odds ratios and 95% confidence intervals, controlling for education and study center. We observed elevated adjusted odds ratios of 2.1 (95% confidence interval: 0.9, 4.8) and 2.0 (95% confidence interval: 1.1, 3.6) for clomiphene and ART exposure, respectively. We performed a mediation analysis to assess whether the observed elevated NTD risk was mediated through multiple births. For clomiphene exposure without ART use, the direct effect estimate of the adjusted odds ratio (aORDE) was 1.7 and the indirect effect estimate (aORIE) was 1.4. Conversely, for ART exposure, the aORDE was 0.9 and the aORIE was 2.5. Our findings suggest that relatively little of the clomiphene-NTD association is mediated through the pathway of multiple births, while the ART-NTD association was explained by the multiple-births pathway.

Global Birth Prevalence of Spina Bifida by Folic Acid Fortification Status: A Systematic Review and Meta-Analysis

BACKGROUND

Birth defects remain a significant source of worldwide morbidity and mortality. Strong scientific evidence shows that folic acid fortification of a region's food supply leads to a decrease in spina bifida (a birth defect of the spine). Still, many countries around the world have yet to approve mandatory fortification through government legislation.

OBJECTIVES

We sought to perform a systematic review and meta-analysis of period prevalence of spina bifida by folic acid fortification status, geographic region, and study population.

SEARCH METHODS

An expert research librarian used terms related to neural tube defects and epidemiology from primary research from 1985 to 2010 to search in EMBASE and MEDLINE. We searched the reference lists of included articles and key review articles identified by experts.

SELECTION CRITERIA

Inclusion criteria included studies in English or French reporting on prevalence published between January 1985 and December 2010 that (1) were primary research, (2) were population-based, and (3) reported a point or period prevalence estimate of spina bifida (i.e., prevalence estimate with confidence intervals or case numerator and population denominator). Two independent reviewers screened titles and abstracts for eligible articles, then 2 authors screened full texts in duplicate for final inclusion. Disagreements were resolved through consensus or a third party.

DATA COLLECTION AND ANALYSIS

We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses, or PRISMA, abstracting data related to case ascertainment, study population, folic acid fortification status, geographic region, and prevalence estimate independently and in duplicate. We extracted overall data and any subgroups reported by age, gender, time period, or type of spina bifida. We classified each period prevalence estimate as "mandatory" or "voluntary" folic acid fortification according to each country's folic acid fortification status at the time data were collected (as determined by a well-recognized fortification monitoring body, Food Fortification Initiative). We determined study quality on the basis of sample representativeness, standardization of data collection and birth defect assessment, and statistical analyses. We analyzed study-level period prevalence estimates by using a random effects model (α level of < 0.05) for all meta-analyses. We stratified pooled period prevalence estimates by birth population, fortification status, and continent.

RESULTS

Of 4078 studies identified, we included 179 studies in the systematic review and 123 in a meta-analysis. In studies of live births (LBs) alone, period prevalences of spina bifida were (1) lower in geographical regions with mandatory (33.86 per 100,000 LBs) versus voluntary (48.35 per 100,000 LBs) folic acid fortification, and (2) lower in studies of LBs, stillbirths, and terminations of pregnancy in regions with mandatory (35.22 per 100,000 LBs) versus voluntary (52.29 per 100,000 LBs) fortification. In LBs, stillbirths, and terminations of pregnancy studies, the lowest pooled prevalence estimate was in North America (38.70 per 100,000). Case ascertainment, surveillance methods, and reporting varied across these population-based studies.

CONCLUSIONS

Mandatory legislation enforcing folic acid fortification of the food supply lags behind the evidence, particularly in Asian and European countries. This extensive literature review shows that spina bifida is significantly more common in world regions without government legislation regulating full-coverage folic acid fortification of the food supply (i.e., Asia, Europe) and that mandatory folic acid fortification resulted in a lower prevalence of spina bifida regardless of the type of birth cohort. African data were scarce, but needed, as many African nations are beginning to adopt folic acid legislation.

Is infertility associated with childhood autism?

Concerns persist about a possible link between infertility and risk of autism spectrum disorders (ASD). Interpretation of existing studies is limited by racial/ethnic homogeneity of study populations and other factors. Using a case-control design, we evaluated infertility history and treatment documented in medical records of members of Kaiser Permanente Northern California. Among singletons (349 cases, 1,847 controls), we found no evidence to support an increase in risk of ASD associated with infertility. Among multiple births (21 cases, 54 controls), we found an increased risk associated with infertility history and with infertility evaluations and treatment around the time of index pregnancy conception; however, small sample size and lack of detailed data on treatments preclude firm interpretation of results for multiple births.

Congenital anomalies after assisted reproductive technology

Worldwide, more than 5 million children have been born after assisted reproductive technology (ART), and in many developed countries ART infants represent more than 1% of the birth cohorts. It is well known that ART children are at increased risk of congenital malformations even after adjustment for known confounders such as maternal age. The proportion of ART children is not negligible, and knowledge about the causes of the higher risk of congenital malformations is crucial to develop prevention strategies to reduce the future risk in ART children. The aim of this review is to summarize the literature on the association between ART and congenital anomalies with respect to subfertility, fertility treatment other than ART, and different ART methods including intracytoplasmic sperm injection, blastocyst culture, and cryotechniques. Trends over time in ART and congenital anomalies will also be discussed.

Use of clomiphene citrate and birth defects, National Birth Defects Prevention Study, 1997-2005

BACKGROUND

Clomiphene citrate (CC) is the first line drug for subfertility treatment. Studies assessing the association between CC and birth defects have been inconclusive.

METHODS

We used data from the National Birth Defects Prevention Study, a population-based, multi-site case-control study of major birth defects. Women from 10 US regions with deliveries affected by at least one of >30 birth defects (cases) and mothers of live born infants without a major birth defect (controls) who delivered October 1997-December 2005 were interviewed. The exposure of interest was reported CC use in the period from 2 months before conception through the first month of pregnancy. Women who conceived using assisted reproductive technology were excluded. Thirty-six birth defect categories with at least three exposed cases were studied. Multiple logistic regression was used to control for potential confounders.

RESULTS

CC use was reported by 1.4% of control mothers (94/6500). Among 36 case-groups assessed, increased adjusted odds ratios (aOR) were found [all: aOR, 95% confidence interval (CI)] for anencephaly (2.3, 1.1-4.7), Dandy-Walker malformation (4.4, 1.7-11.6), septal heart defects (1.6, 1.1-2.2), muscular ventricular septal defect (4.9, 1.4-16.8), coarctation of aorta (1.8, 1.1-3.0), esophageal atresia (2.3, 1.3-4.0), cloacal exstrophy (5.4, 1.6-19.3), craniosynostosis (1.9, 1.2-3.0) and omphalocele (2.2, 1.1-4.5).

CONCLUSIONS

Several associations between CC use and birth defects were observed. However, because of the small number of cases, inconsistency of some findings with previous reports, and the fact that we cannot assess the CC effect separately from that of the subfertility, these associations should be interpreted cautiously.

Reproductive patterns among Danish women with oral clefts

OBJECTIVE

The aim of this study was to compare reproduction patterns among Danish women born with isolated oral clefts versus the Danish background population.

DESIGN AND SETTING

A nationwide population-based historic cohort study based on three registers: The Danish Facial Cleft Register, The Danish Civil Registration System, and the Fertility of Women and Couples Dataset.

PARTICIPANTS

Through linkages of the registers, the number of children and the exact age at childbirth of all Danish women born with an oral cleft from 1950 through 1988 (N = 1931) were obtained. These data were compared with similar data for the entire Danish female background population (N = 1,184,390).

RESULTS AND CONCLUSIONS

This study suggests that childlessness is higher among women born with an oral cleft (55%) than among women in the Danish background population (44%). Excluding women without children, women born with oral cleft had an average of 1.98 children per woman. This did not differ significantly from the background population (2.02 children/woman). Furthermore, the present study found that Danish women born with oral clefts on average were older (27.3 years of age) than the background population (24.7 years of age) when they had their first child (difference = 2.6 years, confidence interval = 2.41 to 2.80).

CONCLUSION

Danish women born with an oral cleft more often are childless or have their first child later, but if they have children, they tend to have as many children as other Danish women. Social, psychological, and biological reasons might be responsible for the reduced fertility.