Biparietal diameter, fetal maturity, and body weight in rural Tanzanian newborns.

The biparietal diameter (BPD) in 202 rural Tanzanian newborns was measured and correlated to maturity and body weight. The mean BPD at birth was 9.0 cm. The average body weight was 2642 g. Fetal maturity was determined by Petrussa score, serving as an estimate for gestational age. The mean gestational age of the 202 newborns was 39 weeks. The average body weight of the mature babies (gestational age 38-40 weeks) was 2765 g. All babies less than 38 weeks of gestation were born with a low birth weight (LBW < or = 2500 g) except for one. The LBW-babies comprised 34 per cent of the total births. About two-thirds of all LBW-babies (62 per cent) were born small for date, only 38 per cent preterm. Regression analysis of the data set was performed resulting in significant models of estimates of gestational age and body weight from BPD as well as body weight from gestational age. In a baby older than 35 weeks of gestation a body weight of more than 1500 g can be expected. With regard to maturity (> or = weeks) and body weight (> or = 1500 g) there is a good chance of survival when the BPD exceeds 7.5 cm. The analysis of our data denotes that tables from industrialized countries relating gestational age to sonographically measured BPD are not applicable for pregnancies in developing countries.