22 October 2009

Male fertility impacted by stress in the womb

by Kate Melville

A surprising new study has found that exposure to a combination of excess stress hormones and chemicals while in the womb can affect a man's fertility in later life. The researchers, from the University of Edinburgh, looked at the effect of glucocorticoids (stress hormones) combined with a common chemical (dibutyl phthalate) used in glues, paints and plastics. They found that the combination dramatically increased the likelihood of male reproductive birth defects.

The defects included cryptorchidism, when the testes fail to drop, and hypospadias, when the urinary tract is incorrectly aligned. In recent times these conditions have become the most common birth defects in male babies - and the rates of incidence are still climbing.

"What the study shows is that it is not simply a case of one factor in isolation contributing to abnormalities in male development but a combination of both lifestyle and environmental factors, which together have a greater impact," explained researcher Dr Mandy Drake.

In most studies to date, reproductive disorders have only been seen in connection with extremely high levels of chemicals, which most humans are not exposed to in everyday life. But this new study shows that the additional exposure to stress combined with lower levels of chemicals can cause adverse affects.

Specifically, the study found that; "exposure to dibutyl phthalate had some effects on reproductive development, [which] was significantly increased with simultaneous exposure to stress hormones." The stress hormones had no effect on male fetal development on their own, although raised levels led to lower birth weights.

The study, published in the journal Endocrinology, noted that between eight and 12 weeks into pregnancy is a crucial period for male reproductive development. During this timeframe, testosterone is produced which affects development of male reproductive organs and fertility in later life.

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Study links penis size to general health
Y chromosome makes sex disorders a "roulette game," say researchers
BPA found to have "dramatic" effect on adult hormone levels

Source: University of Edinburgh