Hypospadias: One Defect, Multiple Causes, Acting Through Shared Pathways

Maternal exposure to DDT, DDE, and pyrethroid insecticides for malaria vector control and hypospadias in the VHEMBE birth cohort study, Limpopo, South Africa

Hypospadias is the ectopic opening of the urethra on the penis or scrotum. Exposure to estrogenic and/or anti-androgenic chemicals in utero may play an etiologic role. DDT and the pyrethroids cypermethrin and deltamethrin, are used to control malaria. DDT is estrogenic and its breakdown product DDE is anti-androgenic; cypermethrin and deltamethrin can also disrupt androgen pathways. We examined the relationship between maternal exposure to these insecticides during pregnancy and hypospadias among boys participating in the Venda Health Examination of Mothers, Babies and their Environment (VHEMBE) in Limpopo Province, South Africa. We measured peripartum levels of p,p'-DDT and p,p'-DDE in maternal serum and urinary pyrethroid metabolites. We conducted urogenital examination on 359 one-year-old boys. A total of 291 (81.0 %) had phimosis, which prevented full urogenital examination, leaving a final sample of 68 boys for determination of the presence of hypospadias. Diagnosis was based on concordance of two independent physicians. We identified hypospadias in 23 of the 68 boys (34 %). Maternal urinary concentrations of cis-DCCA and trans-DCCA metabolites of cypermethrin and other pyrethroids, were associated with an increased risk for hypospadias, but the other metabolite 3-PBA was not (adjusted relative risk per 10-fold increase = 1.58, 95 % CI 1.07-2.34; 1.61, 95 % CI 1.09-2.36; and 1.48, 95 % CI 0.78-2.78, respectively). No associations were found between p,p'-DDT, p,p'-DDE, 3-PBA or cis-DBCA and hypospadias. We observed a high prevalence of hypospadias among boys without phymosis. Boys with higher prenatal exposure to pyrethroid insecticides were at higher risk of hypospadias. Our findings may have global implications given that pyrethroid insecticides are widely used for malaria control, in agriculture and for home use.

Fertility in men with hypospadias: A nationwide register-based study using dizygotic twinning rates as an indicator of semen quality

BACKGROUND

It is not known if impaired fertility in men with hypospadias is caused by decreased semen quality or other factors. Semen quality in men born with hypospadias may be impaired due to effects of androgens or testicular dysgenesis but has been very little studied.

OBJECTIVES

To study semen quality in men with hypospadias using dizygotic twinning rates as an epidemiological indicator. We further aimed to study men treated for cryptorchidism, given a hypothesized mutual etiology for decreased semen quality.

MATERIALS AND METHODS

We conducted a population-based study using national Swedish registers. A total of 4,363,165 births between 1964 and 2013 were included. The association between hypospadias and cryptorchidism, and fathering dizygotic multiple births was estimated using logistic regression and presented as odds ratios. The main analyses excluded births conceived using assisted reproductive technology (ART).

RESULTS

We identified a total of 5317 births with fathers with hypospadias, including 26 dizygotic births conceived unassisted. No significant association was found between hypospadias and dizygotic twinning (OR 1.10, 0.75-1.61). We estimated a significantly increased odds for dizygotic multiple births in men treated for cryptorchidism (OR 1.35, 1.01-1.81) which was decreased after exclusion of ART, but the estimate was not significant (OR 0.75, 0.48-1.18).

DISCUSSION

Using dizygotic twinning rates as an indicator of semen quality, we did not find any difference between fathers with hypospadias and controls. Due to sample size, we could not analyze phenotypes separately and can therefore not exclude impaired semen quality in severe hypospadias. We could not demonstrate any association between dizygotic twinning and cryptorchidism. Men treated for cryptorchidism were more likely than controls to use ART to conceive.

CONCLUSION

Men with hypospadias who conceived without ART were not shown to have impaired semen quality using dizygotic twinning as an epidemiological indicator.