Plasma oestriol in normal pregnancy in an Asian population

Serial plasma oestriol levels were measured by a radioimmunoassay in 49 normal pregnancies, Plasma oestriol rose from 43 ng/ml (149-1 nmol/l) at 22 weeks to 357 ng/ml (1237-91 nmol/l) at 40 weeks. The rise was gradual between 22 and 32 weeks and steep between 32 and 40 weeks. No significant relationship could be found between plasma oestriol and parity, maternal age, maternal height, maternal weight or fetal sex. However, a significant but low correlation was found between birth weight and plasma oestriol prior to labour and also oestriol increments from 30 weeks to delivery. The average day to day coefficient of variation of plasma oestriol in 11 patients was found to be 16-2 per cent.