Influence of Preterm Birth and Birth Size on Gonadal Function in Young Men

Background/Objectives: Preterm birth has been associated with reduced reproduction rates and being born small for gestational age (SGA) with reduced gonadal function. We hypothesized that alterations concerning gonadal function in young men are not due to preterm birth or being born SGA, but are due to other (environmental) factors. Methods: In 207 young men of the PROGRAM/PREMS cohort study, aged 18-24 yr, the influence of preterm birth, birth length, and birth weight on serum levels of anti-Mullerian hormone, inhibin B, testosterone, SHBG, non-SHBG-bound testosterone, LH, and FSH was analyzed with multiple regression modeling. In addition, markers of male gonadal function were analyzed in four subgroups: men born SGA with either short stature or catch-up growth, or men born appropriate for gestational age with idiopathic short stature or with normal stature (control). Results: Preterm birth and SGA did not affect gonadal function. After adjustment for age, birth size, adult height, fat mass, and socioeconomic status (SES), preterm birth even showed a positive relation with inhibin B. Higher SES was associated with higher inhibin B levels. Higher fat mass was associated with decreased testosterone and SHBG levels and maternal smoking with increased LH and non-SHBG-bound testosterone levels. After adjustment for confounders, there were no significant differences in gonadal function between the subgroups. Conclusion: Preterm birth and SGA did not affect gonadal function in young men. Factors that affected gonadal function were: lower SES, a higher fat mass, and maternal smoking during pregnancy. (J Clin Endocrinol Metab 94: 4243-4250, 2009)