Prenatal testosterone exposure is linked to sexually dimorphic changes in body composition in 7-year-old children.

Context: Maternal free testosterone (FT) increases during 3rd trimester and FT is higher in pregnant women with polycystic ovary syndrome (PCOS) compared to women without PCOS. Higher prenatal androgen exposure has previously been associated with increased catch-up growth in boys.

Objective: To examine associations between maternal 3rd trimester testosterone and body composition in boys and girls.

Design, Setting, And Participants: This study comprised 1,008 mother-child pairs (boys, n=520) in Odense Child Cohort (maternal PCOS, n=101). Maternal FT was calculated from total testosterone (TT), analyzed by mass spectrometry at gestational week 28. Body composition assessments were performed in 7-year-old children by whole-body Dual X-ray Absorptiometry (DXA, n=897, measuring body fat (fat mass index (FMI = fat mass(kg)/height(m)2), percentages of total fat mass, gynoid- and android fat mass) and lean body mass, bodyweight, body mass index (BMI and BMI z-scores), and abdominal circumference.

Main Outcome: Body fat at 7 years of age.

Results: In boys, a doubling in FT was associated with a 4.2 % increase in FMI (p=0.04) and an increase in BMI and BMI z-score of 0.2 kg/m2 and 0.1 (p=0.05 and 0.04), respectively. In girls, no significant association was observed between maternal FT and body composition.

Conclusion: Boys exposed to higher prenatal levels of FT had higher fat mass, whereas no relation was seen in girls; suggesting a sex specific susceptibility to prenatal testosterone exposure on child body composition.