Maternal use of oral contraceptives and risk of hypospadias – a population-based case-control study

The Male Reproductive System and Endocrine Disruptors

The male reproductive system is exposed to a great number of chemical substances which can interfere with the normal hormonal milieu and reproductive function; these are called endocrine disruptors (EDs). Despite a growing number of studies evaluating the negative effects of EDs, their production is continuously growing although some of which have been prohibited. The prevalence of poor semen quality, hypospadias, cryptorchidism, and testicular cancer have increased in the last decades, and recently, it has been postulated that these could all be part of a unique syndrome called testicular dysgenesis syndrome. This syndrome could be related to exposure to a number of EDs which cause imbalances in the hormonal milieu and oestrogenic over-exposure during the foetal stage. The same EDs can also impair spermatogenesis in offspring and have epigenetic effects. Although studies on animal and in vitro models have raised concerns, data are conflicting. However, these studies must be considered as the basis for future research to promote male reproductive health.

Endocrine disrupting chemicals in the pathogenesis of hypospadias; developmental and toxicological perspectives

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Penis development is regulated by a tight balance of androgens and estrogens.

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EDCs that impact androgen/estrogen balance during development cause hypospadias.

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Cross-disciplinary collaborations are needed to define a mechanistic link.

Hypospadias is a defect in penile urethral closure that occurs in approximately 1/150 live male births in developed nations, making it one of the most common congenital abnormalities worldwide. Alarmingly, the frequency of hypospadias has increased rapidly over recent decades and is continuing to rise. Recent research reviewed herein suggests that the rise in hypospadias rates can be directly linked to our increasing exposure to endocrine disrupting chemicals (EDCs), especially those that affect estrogen and androgen signalling. Understanding the mechanistic links between endocrine disruptors and hypospadias requires toxicologists and developmental biologists to define exposures and biological impacts on penis development. In this review we examine recent insights from toxicological, developmental and epidemiological studies on the hormonal control of normal penis development and describe the rationale and evidence for EDC exposures that impact these pathways to cause hypospadias. Continued collaboration across these fields is imperative to understand the full impact of endocrine disrupting chemicals on the increasing rates of hypospadias.

Pubertal development after unintended intrauterine exposure to oral contraceptives: a nationwide cohort study

OBJECTIVE

To study the associations between exposure to oral contraceptives before conception and early in pregnancy and pubertal timing in boys and girls.

DESIGN

Population-based cohort study.

SETTING

Not applicable.

PATIENT(S)

Overall, 15,800 children (70%) born during 2000-2003 into the Danish National Birth Cohort were categorized according to maternal use of combined oral contraceptive pills or progestin-only pills reported around gestational week 17: no exposure (reference), exposure 4 months before conception, and exposure in early pregnancy. Children self-assessed pubertal status using Web-based questionnaires from 11 years and biannually throughout puberty.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Adjusted mean age differences (months) for attaining individual pubertal milestones and overall pubertal timing. Proportion mediated by prepubertal body mass index.

RESULT(S)

In boys, intrauterine exposure to oral contraceptives showed a tendency toward slightly earlier mean age for voice break (months, -3.8; 95% confidence interval [CI] -6.5, -1.0) and first ejaculation (months, -2.9; 95% CI -5.9, 0.1) and a mean difference of -1.4 months (95% CI -3.3, 0.4) for overall pubertal timing. Girls with intrauterine exposure tended to have slightly earlier age at menarche (months, -1.9; 95% CI -4.0, 0.3) and Tanner breast stages and had a mean difference of -0.9 months (95% CI -2.7, 1.0) for overall pubertal timing. Exposure before conception was not associated with pubertal timing. Prepubertal body mass index did not play a mediating role.

CONCLUSION(S)

This study shows some evidence that intrauterine exposure to oral contraceptives might slightly affect pubertal timing.

Oral contraceptive use and genital anomalies in sons. A Danish cohort study

Exposure to exogenous sex hormones with estrogenic or anti-androgen properties may influence intrauterine development of male genitals. This population-based cohort study based on data from 44,408 live-born singleton sons in the Danish National Birth Cohort (DNBC) aimed to investigate whether maternal use of oral contraceptives prior to or during early pregnancy increase the risk of cryptorchidism or hypospadias. We found no consistent association between use of oral contraceptives and cryptorchidism or hypospadias, neither in those exposed any time four months prior to conception [cryptorchidism: adjusted Odds Ratio (aOR): 1.06 (95% CI: 0.91; 1.23), hypospadias: 0.74 (95% CI: 0.53; 1.03)] nor in those exposed any time during the first trimester of pregnancy [cryptorchidism: aOR: 0.93 (95% CI: 0.53; 1.62), hypospadias: 1.02 (95% CI: 0.32; 3.23)]. Despite relatively strong exposure levels from oral contraceptive use in pregnancy, this study revealed no evidence of an increased risk of either two genital malformations.

Pharmacologic and Environmental Endocrine Disruptors in the Pathogenesis of Hypospadias: a Review

PURPOSE OF REVIEW

Endocrine disrupting chemicals (EDCs) potentially have a role in causing hypospadias malformation through modifiable in-utero exposure. Considering the emerging literature on the role of potential endocrine disrupting substances on the occurrence of hypospadias and the potential to inform public health efforts to prevent the occurrence of these malformations, we have summarized the current literature, identified areas of consensus, and highlighted areas that warrant further investigation.

RECENT FINDINGS

Pharmaceuticals, such as diethylstilbestrol, progestin fertility treatments, corticosteroids, and valproic acid, have all been associated with hypospadias risk. Data on exposure to dichlorodiphenyltrichloroethane and hexachlorobenzene pesticides, as well as non-persistent pollutants, particularly phthalates, is less consistent but still compelling. Improving exposure assessment, standardizing sample timing to relevant developmental windows, using clear case identification and classification schemes, and elucidating dose-response relationships with EDCs will help to provide clearer evidence. Promising directions for future research include identification of subgroups with genetic hypospadias risk factors, measurement of intermediate outcomes, and study of EDC mixtures that will more accurately represent the total fetal environment.

Maternal hypertension and hypospadias in offspring: A systematic review and meta-analysis

BACKGROUND

Several studies have reported an association between maternal hypertensive disorders and hypospadias in offspring; however there is still debate on the role of maternal hypertension and preeclampsia on this relatively common congenital malformation. Therefore, we conducted a systematic review and meta-analysis to comprehensively evaluate the relationship between these frequent maternal conditions and hypospadias in offspring.

METHODS

Fifteen articles meeting the eligibility criteria were identified in our search and included in the analysis. A meta-analysis was conducted and pooled odds ratio (OR) estimates were calculated separately for hypertension and preeclampsia using meta-analysis. We also conducted several secondary analyses, including (a) studies conducted before versus after January 1, 1998; (b) studies in United States versus other countries; and (c) studies that accounted for ≥3 versus fewer or no potential confounders, among others.

RESULTS

Significant positive associations were observed between hypertension and hypospadias (OR 1.68; 95% CI 1.46-1.93), as well as preeclampsia and hypospadias (OR 2.18; 95% CI 1.63-2.91). The direction and magnitude of effect was comparable for the majority of secondary analyses conducted.

CONCLUSIONS

Our results indicate that maternal hypertensive disorders are positively associated with hypospadias in offspring. Further research is needed to better understand the mechanisms involved, and to ultimately develop public health strategies geared toward prevention of hypospadias.

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.

Genetic and environmental factors in the aetiology of hypospadias

This article reviews the current evidence and knowledge of the aetiology of hypospadias. Hypospadias remains a fascinating anomaly of the male phallus. It may be an isolated occurrence or part of a syndrome or field defect. The increasing use of assisted reproductive techniques and hormonal manipulation during pregnancy may have been associated with an apparent rise in the incidence of hypospadias. Genetic studies and gene analysis have suggested some defects that could result in hypospadias. New light has also been thrown on environmental factors that could modulate candidate genes, causing altered development of the male external genitalia.

Review of genetic and environmental factors leading to hypospadias

Hypospadias is one of the most common congenital malformations, affecting about 4-6 males per 1000 male births, and ranging in severity from a urethral meatus that is slightly off-center to a meatus in the perineal area. Over the past three decades its prevalence may have increased due to changes in reporting of mild cases and/or increased survival of low birth weight infants due to improved neonatal care. However, despite the increasing numbers of males with hypospadias, the overall etiology remains unclear and likely multifactorial in nature. The purpose of this review article is to provide a comprehensive overview of the various factors implicated in hypospadias etiology, including genetic and environmental factors. In addition, we list syndromes in which hypospadias is a relatively common association and delineate the areas that require further investigation in an effort to understand this condition.

Environmental and genetic contributors to hypospadias: a review of the epidemiologic evidence

This review evaluates current knowledge related to trends in the prevalence of hypospadias, the association of hypospadias with endocrine-disrupting exposures, and the potential contribution of genetic susceptibility to its etiology. The review focuses on epidemiologic evidence. Increasing prevalence of hypospadias has been observed, but such increases tend to be localized to specific regions or time periods. Thus, generalized statements that hypospadias is increasing are unsupported. Owing to the limitations of study designs and inconsistent results, firm conclusions cannot be made regarding the association of endocrine-disrupting exposures with hypospadias. Studies with more rigorous study designs (e.g., larger and more detailed phenotypes) and exposure assessment that encompasses more breadth and depth (e.g., specific endocrine-related chemicals) will be critical to make better inferences about these important environmental exposures. Many candidate genes for hypospadias have been identified, but few of them have been examined to an extent that enables solid conclusions. Further study is needed that includes larger sample sizes, comparison groups that are more representative of the populations from which the cases were derived, phenotype-specific analyses, and more extensive exploration of variants. In conclusion, examining the associations of environmental and genetic factors with hypospadias remain important areas of inquiry, although our actual understanding of their contribution to hypospadias risk in humans is currently limited.

Aetiology of hypospadias: a systematic review of genes and environment

BACKGROUND

Hypospadias is a common congenital malformation of the male external genitalia. Most cases have an unknown aetiology, which is probably a mix of monogenic and multifactorial forms, implicating both genes and environmental factors. This review summarizes current knowledge about the aetiology of hypospadias.

METHODS

Pubmed was used to identify studies on hypospadias aetiology published between January 1995 and February 2011. Reference lists of the selected manuscripts were also searched to identify additional studies, including those published before 1995.

RESULTS

The search provided 922 articles and 169 articles were selected for this review. Studies screening groups of patients with hypospadias for single gene defects found mutations in WT1, SF1, BMP4, BMP7, HOXA4, HOXB6, FGF8, FGFR2, AR, HSD3B2, SRD5A2, ATF3, MAMLD1, MID1 and BNC2. However, most investigators are convinced that single mutations do not cause the majority of isolated hypospadias cases. Indeed, associations were found with polymorphisms in FGF8, FGFR2, AR, HSD17B3, SRD5A2, ESR1, ESR2, ATF3, MAMLD1, DGKK, MID1, CYP1A1, GSTM1 and GSTT1. In addition, gene expression studies indentified CTGF, CYR61 and EGF as candidate genes. Environmental factors consistently implicated in hypospadias are low birthweight, maternal hypertension and pre-eclampsia, suggesting that placental insufficiency may play an important role in hypospadias aetiology. Exogenous endocrine-disrupting chemicals have the potential to induce hypospadias but it is unclear whether human exposure is high enough to exert this effect. Other environmental factors have also been associated with hypospadias but, for most, the results are inconsistent.

CONCLUSIONS

Although a number of contributors to the aetiology of hypospadias have been identified, the majority of risk factors remain unknown.