Growth of the uterus and mammary glands and vaginal cytologic features in extremely premature infants with postnatal replacement of estradiol and progesterone

Objective: Growth of the uterus and the mammary glands and changes in vaginal cytologic features are known to be estrogen dependent and were evaluated to proof the biologic effectiveness of a postnatal replacement of estradiol and progesterone in extremely premature infants. Study Design: Thirty female infants with a mean gestational age of 26.4 weeks (24.1-28.7 weeks) and a mean birth weight of 708 g (370-990 g) were investigated. Fifteen infants received postnatal replacement of estradiol and progesterone for 6 weeks to maintain intrauterine plasma levels of estradiol and progesterone. Uterine size and the diameter of mammary glands were assessed repeatedly by ultrasound scans and palpation. Vaginal smears were also obtained. Results: The uterus and mammary glands showed significant growth during the hormone replacement, but growth was not observed in nontreated infants. Vaginal smears showed high karyopyknotic and eosinophilic indices in both groups at birth; the indices remained significantly higher at 3 and 6 weeks in the hormone-treated infants. Conclusion: The biologic effectiveness of postnatal estradiol and progesterone replacement in extremely premature infants was proved. (Am J Obstet Gynecol 2002;186:184-8.)