US assessment of estrogen-responsive organ growth among healthy term infants: piloting methods for assessing estrogenic activity
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A mother’s circulating estrogen increases over the third trimester, producing physiological effects on her newborn that wane postnatally. Estrogenization might be prolonged in newborns exposed to exogenous estrogens, such as isoflavones in soy formula.
We evaluated ultrasonography for monitoring growth of multiple estrogen-responsive organs in healthy infants and developed organ-growth trajectories.
Materials and methods
We studied 38 boys (61 visits) from birth to age 6 months and 41 girls (96 visits) from birth to age 1 year using a partly cross-sectional, partly longitudinal design. We measured uterus and ovaries in girls, testes and prostate in boys, and kidneys, breasts, thymus, and thyroid in all children. We imaged all organs from the body surface in one session of < 1 h.
Uterine volume decreased from birth (P < 0.0001), whereas ovarian volume increased sharply until age 2 months and then decreased (P < 0.001). Testicular volume increased with age (P < 0.0001), but prostatic volume showed minimal age trend. Breast bud diameter showed no age trend in girls but declined from birth in boys (P = 0.03).
US examination of multiple estrogen-responsive organs in infants in a single session is feasible and yields volume estimates useful for assessing potential endocrine disruptor effects on organ growth.
KeywordsUS Infant Organ growth Soy formula
This research was supported by the Intramural Research Program of the NIH, National Institute of Environmental Health Sciences (NIEHS). RHNN was an NIEHS Intramural Postdoctoral Fellow at the time of this work. The authors appreciate study coordination and analysis assistance of Janet Archer and Holly Schmidt-Davis; clinical contributions of Jane Share, Kathy Howard, Julie Hart, and Deirdre Ellard; recruitment assistance by Drs. Joanne Cox and Lise Johnson; imaging supervision at BWH by Dr. Carol Benson, and imaging by all participating sonologists at BWH and Children’s Hospital Boston.