Gonadotropin levels in urine during early postnatal period in small for gestational age preterm male infants with fetal growth restriction.

OBJECTIVE: The objective of this study was to estimate gonadotropin concentrations in small for gestational age (SGA) male infants with the reactivation of the hypothalamic-pituitary-gonadal axis during the first few months of life that is important for genital development.

STUDY DESIGN: We prospectively examined 15 SGA and 15 appropriate for gestational age (AGA) preterm male infants between 2013 and 2014 at Kyoto University Hospital. Gonadotropin concentrations (luteinizing hormone (LH) and follicle-stimulating hormone (FSH)) were measured in serial urine samples from the postnatal days 7 to 168 and compared between SGA and AGA infants using the Mann-Whitney test.

RESULTS: A longitudinal analysis showed that SGA infants had higher LH and lower FSH concentrations (P=0.004 and P=0.006, respectively) than AGA infants.

CONCLUSION: Male infants who are SGA at birth because of fetal growth restriction have gonadotropin secretion abnormalities in the first few months of life.