Does smoking during pregnancy affect sons' sperm counts?
BACKGROUND
There has been an apparent decline in sperm density during the last 5 decades in Denmark, a country in which women have among the highest rates of smoking in Europe. We examined semen quality and sex hormones in men in relation to their mothers' tobacco smoking during pregnancy.


METHODS
Male participants were selected from the population-based Danish Twin Registry and the Danish Civil Registration System as part of a study on hereditary and environmental determinants of semen quality. From November 1999 to May 2000 we collected one fresh semen and blood sample from each of 316 men. Data on prenatal tobacco exposure were obtained for 265 of these men from a questionnaire filled in by their mothers.


RESULTS
Adjusting for age, current smoking status and other factors, sperm density was 48% lower(95% confidence interval = -69% to -11) among sons of mothers who smoked more than 10 cigarettes per day during pregnancy. Total sperm counts and levels of inhibin-B were also reduced among this group, whereas follicular stimulating hormone levels were somewhat higher (16% increase; 95% confidence interval = -13% to 54%). These effects were not seen in the lower smoking category (1-10 cigarettes per day).


CONCLUSIONS
High levels of smoking (> 10 cigarettes per day) during pregnancy may be a partial explanation for the apparent secular decline and the geographic differences in sperm counts.
Storgaard
Lone
L
Department of Occupational Medicine, Aarhus University Hospital, Denmark. lstor@akh.aaa.dk
Bonde
Jens Peter
JP
Ernst
Erik
E
Spanô
Marcello
M
Andersen
Claus Yding
CY
Frydenberg
Morten
M
Olsen
Jørn
J
D000328:Adult; D001724:Birth Weight; D003718:Denmark; D005260:Female; D006801:Humans; D028322:Inhibin-beta Subunits / Q000032:analysis; D008297:Male; D007752:Obstetric Labor, Premature; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology; D011297:Prenatal Exposure Delayed Effects; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology; D013076:Sperm Count; D014427:Twins
D028322:Inhibin-beta Subunits