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Intrauterine Growth Retardation and Pituitary Gonadal Function« Back to Volume 23, Issue 3, November 2007 - Table of Contents Low birth weight as a consequence of intrauterine growth retardation (IUGR) is associated with an increased risk of disease in adult life. It has been reported to have a detrimental effect on gonadal development in boys, including cryptorchidism and hypospadias. Little is known on the male pituitary-gonadal axis functioning in adulthood. Small for gestational age (SGA) is a result of IUGR during variable periods of gestation, hence a consequence of different adverse events occurring during gestation. This study focused on fetal growth restraint occurring during the third trimester of pregnancy; the authors hypothesized that IUGR in the third trimester of pregnancy would determine the ultimate male reproductive function. Jensen also evaluated the influence of birth weight in relation to gestational age on the pituitary-testicular axis. Participants were recruited from a large prospective study of pregnant women who provided third trimester fetal growth velocity and birth weight. Fifty-two adolescent males participated in the follow-up study and were divided into appropriate for gestational age ([AGA] n=32) and SGA (n=20). The authors were careful to avoid major selection bias. Pubertal stage, testicular size, and reproductive hormones were determined, including overnight LH and FSH profiles. No significant differences were found in testosterone levels, inhibin B levels and LH/testosterone ratio between AGA and SGA. Neither difference was observed between both groups for testicular size and morphology (determined by ultrasonography and overnight secretory patterns of gonadotropins). Median basal LH secretory rates were two-fold higher in men born AGA but the difference did not reach statistical significance. Fetal growth during the third trimester of pregnancy did not influence any of the reproductive hormone levels nor their secretory pattern as estimated by deconvolution analysis. This is the first study to explore the influence of the third trimester fetal growth rate on subsequent adult gonadal function. These results do not rule out the gonadal damage in relation to genital malformations as cryptorchidism and hypospadias which also occur in relation with SGA. The testicular function was not impaired in adolescent males born after compromised fetal growth hormones. Jensen RB, Vielwerth S, Larsen T, Greisen G, Veldhuis J, Juul A. Pituitary-gonadal function in adolescent males born appropriate or small for gestational age with or without intrauterine growth restriction. J Clin Endocrinol Metab. 2007;92:1353-7. Editor’s CommentMost IUGR studies have focused on female reproductive function and have suggested that young women born SGA have reduced ovarian volume, decreased ovarian hormones, and increased number of anovulatory cycles.1,2 Hyperinsulinemic insulin resistance occurring in these girls is also considered a setting for subsequent development of PCOS in adult women. The rise in FSH levels is greater during infancy in both boys and girls born SGA, whereas inhibin B levels are similar to those in infants born AGA. In adolescent males there is only limited information suggesting impaired spermatogenesis. In only one clinical study3 of males, a significantly decreased testosterone secretion and elevated LH levels were reported, suggesting primary testicular failure in men born SGA. In 54% of those subjects, a mean testicular volume >2 SD below the control mean, with reduced inhibin B was detected; the authors considered that their data supported a link between between low birth weight and reduced fertility in males born SGA. The presence of cryptorchidism in several cases might have played a role in the data they presented.3 The present study provided no evidence for impaired testicular function. It may mean that whatever its cause, late fetal growth restraint is not associated with testicular dysfunction, hence a risk of subfertility. In a recent review4 the limitation of information in this area has been stressed, yet many reports have dealt with connected issues such as cryptorchidism, testicular cancer, and hypospadias. A working hypothesis would be that males with early fetal growth restrain, generally resulting in symmetric SGA, would be at greater risk. Developmental factors would play a role at this early phase of fetal growth. It would require new prospective studies in a setting similar to that reported in this paper to elucidate this hypothesis. Raphaël Rappaport, MD References - (linked to
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Volume 26 Number 1
September 2010
www.GGHjournal.com
ISSN 1932-9032
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