Do paternal semen parameters influence the birth weight or BMI of the offspring? A study from the Utah Population Database

To study the role of individual semen parameters on the offspring birth weight and body mass index (BMI) from a population of men evaluated in an assisted reproduction technology (ART) clinic compared to fertile controls. We performed a retrospective study using a cohort with fertile, age-matched controls of men evaluated with semen analysis at the University of Utah Andrology Clinic from 1996 to 2011 and Intermountain Healthcare from 2002 to 2011. We use the offspring from both our sub-fertile cohort and controls using the Utah Population Database. The two main outcomes of interest were offspring birth weight and adolescent BMI. The offspring of men with impaired sperm parameters had significantly lower birth weight compared to fertile control offspring. Low-concentration offspring weighed 158 g less (95% CI - 278- 38; p = 0.01), low total count weighed 172 g less (95% CI - 294- 51; p = 0.005), and low total motility weighed 155 g less (95% CI - 241- 69; p < 0.001) compared to those of the controls. When we controlled for the use of ART within the sub-fertile group, we found that there was a significant trend of increasing birth weight across levels of total motile count and total sperm count compared to the azoospermic group. We did not find any consistent significant differences between the subject and control adolescence BMI based on semen parameters. Despite limitations within our population-based dataset, we found that poor quality semen analysis parameters pointed towards an association with low birth weight in the offspring of sub-fertile men compared to the offspring of normal fertile controls. However, in contrast to studies of ART effects on offspring, we did not find evidence of long-term associations between semen quality and offspring BMI.