Prenatal, adult smoking exposure may harm male reproductive health
MedWire News: Prenatal exposure to tobacco could cause boys to reach puberty earlier, experience infertility more commonly, and have a higher adult body mass index (BMI), smaller testes, and impaired testicular function compared with those not exposed, say researchers.
Similar trends were observed for some of these associations among men in the study who were current smokers.
The findings confirm the negative impact of exposure to tobacco in utero on male fertility, as has been previously shown in studies that found reduced semen quality in boys born to mothers who smoked during pregnancy.
"We suggest that research should focus on whether fetal exposure to tobacco may lead not only to a reduced reproductive potential but also to a higher risk of metabolic syndrome or other BMI-related diseases and increased risk of late onset hypogonadism," remark Niels Jørgensen (University Department of Growth and Reproduction, Copenhagen, Denmark) and colleagues.
The group measured the effects of prenatal and current tobacco exposure on markers of testicular function and puberty in 3486 Danish men who participated in a semen-quality study between 1996 and 2006.
Participants also completed questionnaires detailing their smoking history, whether their parents smoked during pregnancy, their weight and length at birth, and how their onset of puberty compared with that of their friends.
A total of 40% of the men had been exposed to prenatal maternal smoking; these men had significantly lower median birthweights (3.35 vs 3.55 kg), lower final adult heights (1.80 vs 1.82 m), and a higher BMI, (22.9 vs 22.4) than men who had not been exposed in utero.
Exposed men also had marginally smaller testes than did unexposed men, at a mean 19.8 versus 19.9 ml, a trend that was mirrored among men who currently smoked compared with non-smokers, at 20.4 versus 20.3 ml.
Cryptorchism, and self-reported signs of early puberty such as voice breaking, were reported more frequently by men exposed in utero compared with unexposed men, at 12.6% and 18.3% versus 9.3% and 14.9%, respectively - a result that was marginally significant.
Finally, men whose mothers did not smoke during pregnancy were less likely to report problems with fertility, at 0.4% compared with 0.7% of men who were exposed to tobacco prenatally. A similar trend was also observed among men who currently smoked (and whose mothers smoked during pregnancy) compared with those who were nonsmokers (and who were unexposed to tobacco in utero), at 2.3% versus 1.1%.
The findings "may not be of direct clinical importance for the individual but may be of public health importance," conclude the researchers in the journal Human Reproduction.
MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011
By Sarah Guy