Fetal growth according to different reference ranges in twin pregnancies with placental insufficiency

The aim of this study was to compare different fetal growth curves in twin pregnancies with severe placental insufficiency. A retrospective cross-sectional analysis of 47 twin pregnancies with absent or reverse end diastolic flow in the umbilical artery of one fetus was performed. Pregnancies with major fetal abnormalities, twin-twin transfusion or three or more fetuses were not included. The estimated fetal weight zeta-scores were calculated for both fetuses (abnormal Doppler and co-twin) according to the following criteria: Hadlock, Liao and Araújo. The abdominal circumference zeta-scores were calculated according to Hadlock, Liao, Araújo, Ong and Stirrup. The mean estimates of the zeta-score values were calculated using generalized estimating equation regression analysis. The mean gestational age at inclusion was 27.4 ± 4.7 weeks. The fetal sex and the interaction Doppler findings × criteria correlated significantly with the zeta-score values (p < 0.001 for both variables). The estimated fetal weight mean zeta-scores (standard error) according to each criteria were as follows: Hadlock - abnormal Doppler: -2.98 (0.18), co-twin: -1.16 (0.15); Liao - abnormal Doppler: -2.89 (0.24), co-twin: -0.58 (0.19); and Araújo - abnormal Doppler: -3.05 (0.29), co-twin: -0.75 (0.18). Values for abdominal circumference were as follows: Hadlock - abnormal Doppler: -3.14 (0.26), co-twin: -1.13 (0.19); Liao - abnormal Doppler: -2.63 (0.27), co-twin: -0.42 (0.19); Araújo - abnormal Doppler: -2.44 (0.22), co-twin: -0.71 (0.14); Ong - abnormal Doppler: -3.36 (0.34), co-twin: -1.48 (0.23); and Stirrup AD -- -2.36 (0.14), co-twin: -1.18 (0.10). Sex- and plurality-specific charts should be used in the evaluation of fetal growth in twin pregnancies with placental insufficiency.