Fetal weight gain in a serially scanned high-risk population.

Physiological as well as pathological variables influence fetal growth. This study was undertaken to assess the influence of physiological variables on fetal weight gain in a high-risk population with normal outcome. A total of 121 pregnancies had 3-13 (median 8) ultrasound scans in the third trimester. Estimated fetal weight was calculated according to standard formulae. The estimated fetal weight at 30, 34 and 38 weeks and growth per day in the last 2 weeks prior to delivery were calculated and compared between subgroups defined on physiological characteristics, such as maternal height, maternal weight, parity and fetal sex. There were differences in growth curves for each of the physiological parameters studied. Maternal height and weight were significantly related to the estimated fetal weight throughout the third trimester but there were no significant differences in growth per day in the last 2 weeks before birth. In contrast, subgroups defined by parity and fetal sex did not show significant fetal weight differences in the third trimester, but the daily growth rate prior to birth was significantly higher for multiparae and male fetuses. Physiological factors affect fetal weight gain and need to be taken into account when fetal growth is monitored in high-risk pregnancies.