Birth weight in relation to sex steroid status and body composition in young healthy male siblings.
BACKGROUND
Sex steroid concentrations have a strong genetic determination, but environmental factors and body composition play an important role. From studies in children with intrauterine growth restriction, low birth weight has been associated with altered gonadotropin concentrations.


OBJECTIVE
We aim to investigate sex steroid concentrations in healthy young brothers in relation to birth weight (normal gestational age), body composition, and parental steroid concentrations.


METHODS
We conducted a cross-sectional, population-based sibling pair study with inclusion of parental data.


METHODS
A total of 677 men (25-45 yr old) were included in this study, with 296 independent pairs of brothers and 122 fathers.


RESULTS
We measured testosterone, estradiol, leptin, adiponectin, IGF-I (immunoassays), and free steroid hormones (calculated) in relation to birth weight and changes in body composition (dual-energy x-ray absorptiometry).


RESULTS
Birth weight was associated with serum testosterone (P = 0.0004) and SHBG (P = 0.0001), independent from weight, age, or fat mass, whereas no association with (free) estradiol, LH, or FSH was found. Paternal testosterone (P = 0.02), estradiol (P = 0.04), and SHBG (P = 0.0004) were associated with the respective sex steroid concentrations in the brothers. Weight increase (population rank) during life, was associated with lower testosterone (-15%; P < 0.001), independent from current weight and with higher free estradiol concentrations (+8%; P = 0.002), whereas weight decrease was associated with higher testosterone (+13%; P < 0.001).


CONCLUSIONS
Birth weight and paternal steroid concentrations are associated with testosterone concentrations, independent from adult weight. These findings support the concept of in utero programming across the range of birth weight.
Department of Endocrinology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium.
Griet
G
Vanbillemont
Bruno
B
Lapauw
Veerle
V
Bogaert
Hélène
H
De Naeyer
Dirk
D
De Bacquer
Johannes
J
Ruige
Jean-Marc
JM
Kaufman
Youri E C
YE
Taes
D015502:Absorptiometry, Photon; D054392:Adipokines / Q000097:blood; D000328:Adult; D000375:Aging / Q000502:physiology; D001823:Body Composition / Q000502:physiology*; D001835:Body Weight / Q000502:physiology*; D004958:Estradiol / Q000097:blood; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D010290:Parents; D012738:Sex Hormone-Binding Globulin / Q000032:analysis; D035781:Siblings; D013739:Testosterone / Q000097:blood
D054392:Adipokines; D012739:Gonadal Steroid Hormones; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D004958:Estradiol