Predicting fetal growth deviation in parous women: combining the birth weight of the previous pregnancy and third trimester ultrasound scan.

Aim: To investigate the value of the birth weight of the previous pregnancy (BW1) alone and combined with the third trimester ultrasonographically estimated fetal weight (EFW) and Doppler studies in the prediction of small (SGA) and large for gestational age (LGA) neonates in the index pregnancy (BW2).

Method: Some 1298 parous women with uncomplicated singleton pregnancies who had a third trimester ultrasound scan were considered as samples in this retrospective cohort study. Maternal and pregnancy characteristics, BW1, EFW, umbilical artery, and middle cerebral artery pulsatility indices were investigated as predictors of SGA and LGA.

Results: BW1, maternal weight, mode of conception, and smoking status were associated with BW2 (R2=0.39) with BW1 being the strongest predictor (R2=0.37). The addition of EFW conferred significant improvement (R2=0.63), whereas the addition of the Doppler indices did not. The sensitivity of BW1 alone in the prediction of SGA was 75% for 25% screen positive rate and increased to 92% with the addition of EFW. The equivalent figures for LGA were 68% and 93%, respectively.

Conclusions: BW1 used as a continuous variable is predictive of growth deviations in the index pregnancy. Incorporating EFW enhanced the sensitivity for the detection of both conditions.