ABSTRACT
BACKGROUND: Growing evidence suggests intergenerational effects of paternal pre-conceptional smoking through the germ line, but its specific impact on offspring semen quality remains uncertain because of challenges in isolating paternal exposure from maternal passive smoking or underreporting. METHODS: We reran previous analyses estimating differences in semen parameters and testicular size according to paternal smoking in 867 young adult men, adding first-trimester maternal plasma cotinine to the original adjustment for maternal self-reported smoking. We also estimated differences in sperm DNA fragmentation. Paternal smoking was reported by the pregnant women around gestational week 16. Analyses were additionally adjusted for household occupational status, parental ages at birth, maternal pre-pregnancy body mass index and alcohol consumption, and abstinence time, and accounted for spillage, minutes from ejaculation to analysis, and son's own smoking. RESULTS: We found no association between paternal preconceptional smoking and any of the semen parameters or testicular size. Adjustment for son's own smoking did not change results. DISCUSSION: While maternal plasma cotinine offers an objective measure of tobacco exposure and allows for a more thorough adjustment of maternal smoking, the high correlation between paternal pre-conceptional smoking and maternal cotinine exposure may, have resulted in overadjustment removing some paternal effect. Inability to distinguish between paternal never smokers and former smokers, may have led to misclassification of paternal pre-conceptional smoking and underestimation of associations. CONCLUSION: We found no support for an independent association between paternal pre-conceptional smoking and semen quality in young adult sons, but studies with more detailed paternal smoking history are needed before firm conclusions can be drawn.
ABSTRACT
BACKGROUND: Maternal fever during pregnancy has been associated with an increased risk of genital malformations, but the implication for long-term reproductive health in the offspring is unknown. OBJECTIVES: To investigate associations between timing, duration, and temperature of fetal exposure to maternal fever and sons' semen quality, testicular volume, and levels of reproductive hormones in early adulthood. Further, to examine whether concurrent use of antipyretics and/or antibiotics modified the effect. MATERIALS AND METHODS: We used the Fetal Programming of Semen Quality cohort consisting of men born to women enrolled in the Danish National Birth Cohort. Self-reported information on maternal fever was collected twice during pregnancy (median 16 and 31 pregnancy weeks) and categorized as any fever during pregnancy, fever during early pregnancy (weeks 1-15), and fever exclusively during late pregnancy (weeks 16-42). Semen quality and concentrations of reproductive hormones were measured at a clinical examination at the age of 18.9 years. We used negative binomial regression to examine the associations, adjusting for maternal age at birth, maternal smoking, family occupational status, and precision variables related to semen quality and hormonal levels, for example, abstinence time. RESULTS: 986 men were included in the study, of which 23% had mothers reporting at least one episode of fever. We found no strong indications of associations between maternal fever during pregnancy and male reproductive health in young men. Concurrent use of antipyretics and antibiotics did not modify the association. DISCUSSION: Strengths include the large sample size, prospectively collected data, and the adjustment for maternal factors during pregnancy and important precision variables. A limitation is the crude self-reported information on maternal fever. CONCLUSION: We found no evidence to support that timing, duration, or temperature of maternal fever during pregnancy has a long-term impact on semen characteristics, testicular volume, or level of reproductive hormones in male offspring.
