Pituitary-gonadal function in adolescent males born appropriate or small for gestational age with or without intrauterine growth restriction

CONTEXT: Being born small for gestational age (SGA) is suggested to influence female pituitary-gonadal axis, but only a few studies have focused on male pituitary-gonadal function.

OBJECTIVE: Our objective was to evaluate the influence of fetal growth rate on male reproductive function.

DESIGN: We conducted a follow-up study of a prospective study with data on third trimester fetal growth velocity and birth weight.

SETTING: The study was conducted at Copenhagen University Hospital.

PARTICIPANTS: Fifty-two healthy adolescent males participated. They were divided into those born appropriate for gestational age (AGA) and SGA, with or without intrauterine growth restriction.

MAIN OUTCOME MEASURES: Pubertal stage, testicular size, and reproductive hormones were determined. Overnight 20-min LH and FSH profiles and overnight urine LH and FSH were determined in an additional study (n=30).

RESULTS: No significant differences were found in testosterone levels (19.2 vs. 18.9 nmol/liter), inhibin B levels (186.5 vs. 188.0 pg/ml), or LH/testosterone ratio (0.15 vs. 0.18) between AGA and SGA, respectively. No significant differences in overnight secretory patterns of gonadotropins or testicular size and morphology were determined by ultrasonography between AGA and SGA. Fetal growth velocity did not influence any of the reproductive hormone levels. Overnight urinary LH and FSH excretion correlated statistically significantly with overnight LH (r=0.50; P=0.02) and FSH (r=0.44; P=0.04) secretion, respectively.

CONCLUSION: Poor third trimester growth and/or low birth weight had no effect on subsequent male reproductive hormones. Contrasting a previous study, we found no difference in testosterone or inhibin B levels between SGA and AGA, suggesting that testicular function was not impaired in adolescent males born after compromised fetal growth.