Maternal bereavement and cryptorchidism in offspring

In-utero Exposure to Maternal Stressful Life Events and Risk of Cryptorchidism: The Raine Study

Cryptorchidism, registered at birth or later, is the most common birth defect in males in western countries, estimated to affect around 2-3% of newborn boys, declining to around 2% at 3 months. We have previously described a potential association between stressful life events (SLEs) in pregnancy and reduced semen quality and testosterone levels in adult offspring. Both outcomes are believed to share a common etiology with cryptorchidism thus increased risk of cryptorchidism in boys exposed to prenatal SLEs may be plausible. The risk of cryptorchidism associated with prenatal SLE amongst 1,273 male Generation 2 offspring was estimated using the Western Australian Pregnancy (Raine) Study. SLEs are discrete experiences that disrupt an individual's usual activities causing a life change and readjustment, such as death of a relative or friend, divorce, illness or job loss. Mothers prospectively reported SLEs, during pregnancy at gestational weeks (GW) 18 and 34 using a standardized 10-point questionnaire. A boy was diagnosed as cryptorchid if one or both testes was non-palpable in the scrotum and not able to be manipulated into the scrotum. Twenty-four (2%) cryptorchid boys were identified. Mean (standard deviation) of SLE exposures in GW34 was 1.1 (1.2) for non-cryptorchid boys and slightly higher 1.5 (1.8) for cryptorchid boys, similar differences were observed in GW18. Adjusted odds ratio [OR] and 95% confidence intervals (CI) for risk of cryptorchidism in early (18-weeks) and late gestation (34-weeks) according to prenatal SLE exposures were: 1.06 (95% CI: 0.77-1.45) and 1.18 (95% CI: 0.84-1.67), respectively. This is the first-time report on the possible relationships between exposure to early and late pregnancy SLEs and risk of cryptorchidism in a birth cohort. Prenatal SLE exposure was not associated with a statistically significant increase in the risk of cryptorchidism in male offspring. A small case population limits the statistical power of the study and future larger studies are required to evaluate this potential association.

Nationwide Increase in Cryptorchidism After the Fukushima Nuclear Accident

OBJECTIVE

To estimate the change of discharge rate after cryptorchidism surgery between pre- and postdisaster in Japan. Cryptorchidism cannot be diagnosed before birth and is not a factor that would influence a woman's decision to seek an abortion. Therefore, this disease is considered suitable for assessing how the Great East Japan Earthquake and the subsequent Fukushima Daiichi nuclear accident (2011) influenced congenital diseases.

MATERIALS AND METHODS

We obtained cryptorchidism discharge data collected over 6 years from hospitals that were included in an impact assessment survey of the Diagnosis Procedure Combination survey database in Japan and used these data to estimate the discharge rate after cryptorchidism surgery before and after the disaster. The 94 hospitals in Japan that participated in Diagnosis Procedure Combination system and had 10 or more discharges after cryptorchidism surgery within successive 6 years covering pre- and postdisaster period (FY2010-FY2015) were involved. The change in discharge rate between pre- and postdisaster was analyzed using a Bayesian generalized linear mixed model.

RESULTS

Nationwide, a 13.4% (95% credible interval 4.7%-23.0%) increase in discharge rates was estimated. The results of all sensitivity analyses were similar to the reported main results.

CONCLUSION

The discharge rate of cryptorchidism was increased nationwide. The rates of low-weight babies or preterm births, risk factors of cryptorchidism, were almost constant during the study period, and age distribution of the surgery was also not changed, which suggested that the other factors that associated with the disaster increased the incidence of cryptorchidism.

Risk factors for cryptorchidism

Undescended testis - known as cryptorchidism - is one of the most common congenital abnormalities observed in boys, and is one of the few known risk factors for testicular cancer. The key factors that contribute to the occurrence of cryptorchidism remain elusive. Testicular descent is thought to occur during two hormonally-controlled phases in fetal development - between 8-15 weeks (the first phase of decent) and 25-35 weeks gestation (the second phase of descent); the failure of a testis to descend permanently is probably caused by disruptions to one or both of these phases, but the causes and mechanisms of such disruptions are still unclear. A broad range of putative risk factors have been evaluated in relation to the development of cryptorchidism but their plausibility is still in question. Consistent evidence of an association with cryptorchidism exists for only a few factors, and in those cases in which evidence seems unequivocal the factor is likely to be a surrogate for the true causal exposure. The relative importance of each risk factor could vary considerably between mother-son pairs depending on an array of genetic, maternal, placental and fetal factors - all of which could vary between regions. Thus, the role of causative factors in aetiology of cryptorchidism requires further research.

Invited Commentary: An Ingenious Approach to Examining the Relationship Between Maternal Stress and Offspring Health?

The potentially deleterious effects on offspring health of excess maternal stress in pregnancy are important to understand-both whether observed associations are causal and through what mechanisms their effects may exert an influence. In this issue of the Journal, Räikkönen et al. (Am J Epidemiol. 2012;000(0):000-000) provide an ingenious test of a potential pathway through which maternal stress may influence offspring development. Licorice consumption is known to disrupt the ability of the placental enzyme 11β-hydroxysteroid dehydrogenase type 2 to inactivate cortisol before it reaches the fetus, leading to higher levels of cortisol exposure. Higher levels of cortisol exposure are also hypothesized to underlie the mechanism through which maternal stress may disrupt fetal development. Thus licorice consumption may serve, in some ways, to mimic maternal stress. The authors report associations between heavy licorice consumption during pregnancy and a wide range of offspring outcomes, including changes in pubertal timing, intelligence quotient, and mental health. In our view, these results should be considered preliminary; more work needs to be completed to determine the relationship of prenatal licorice consumption to these outcomes. Nonetheless, these intriguing and suggestive results demonstrate that this line of work should be given high priority, and they set the stage for additional research moving forward.

Reproductive function in the sons of women who experienced stress due to bereavement before and during pregnancy: a nationwide population-based cohort study

OBJECTIVE

To estimate the association between prenatal exposure to maternal stress and reproductive disorders in Danish men, where prenatal stress exposure was defined as the mother's loss of a close relative during pregnancy or in the 12 months before conception.

DESIGN

Population-based cohort study.

SETTING

Not applicable.

PATIENT(S)

All males born in Denmark between 1973 and 2008 (n = 1,217,576) and observed for up to 39 years.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Male reproductive function, defined using a composite outcome including congenital malformations of genital organs, testicular cancer, diagnosis of male infertility, or assisted conception use due to male factor infertility.

RESULT(S)

In total, 28,986 men (2.4%) had been exposed to prenatal stress, and 62,929 (5.2%) experienced the composite outcome during the follow-up period. Prenatal exposure to stress was associated with an elevated risk of reproductive problems (hazard ratio [HR] 1.09; 95% CI, 1.04-1.15). The association was stronger when the exposure occurred during the first trimester of pregnancy, and for congenital malformations of genital organs. When focusing on infertility alone, we saw no evidence of increased risk (HR 0.90; 95% CI, 0.77-1.06). In addition, the probability of marrying a woman was lower for exposed men (HR 0.93; 95% CI, 0.89-0.98).

CONCLUSION(S)

Prenatal stress in the form of the mother's bereavement during the first trimester of pregnancy is associated with a higher risk of reproductive disorders from congenital malformations of the genital organs in the male offspring. The lack of an association between maternal bereavement and later infertility in the exposed male offspring may be due in part to the men's lower probability of attempting to have children.