The relationship between estradiol and bone mineral status has been extensively investigated in postmenopausal women. In vitro studies on the interaction of estrogens on osteoblasts and osteoclasts have shown inconsistent results. Fetal bone mineralisation has its maximum in the early third trimenon and parallels the fetal growth maximum. Fetal bone mineral content (BMC) correlates highly with fetal weight. BMC in the first postnatal days reflects the fetal mineral status. We investigated the relationship between the postnatal BMC and umbilical cord blood estradiol concentration(E2).

Methods: In 15 infants with gestational age (GA) 24-30 wks (median 27) and birthweight (W) 480-1330g (690) we measured E2 concentrations in umbilical cord blood using an ELISA-based testkit. BMC-measurement was performed with single photon absorptions-densitometry on postnatal day 2-8 (5). BMC values were corrected for weight by calculating the BMC/W-quotient.

Results: The lowest BMC/W-quotients (Table) were associated with E2 concentrations below 1200pg/ml (Reference range 2000-10.000(-20.000) pg/ml). The table is sorted for BMC/W.

Table 1
Full size table

Conclusion: We speculate that low E2 concentration during fetal life causes poor fetal bone mineralisation.