Intrapartum Assessment by House Staff of Birth Weight Among Twins

OBJECTIVE: METHODS: RESULTS:The mean birth weight (± standard deviation) for the twin A group was 1910 ± 628 g and for twin B was 1869 ± 668 g. The mean standardized absolute errors for the twin A group (121 ± 118 g/kg) and the twin B group (92 ± 67 g/kg) were not significantly different (P = .06). Analysis of variance revealed that regardless of the presentation of the fetuses, the mean standardized absolute error was not significantly different (P = .10). Using a difference in the estimates of birth weight of 15% or greater, the positive and negative predictive values of detecting discordant growth within a twin pair were 53 and 83%, respectively. Among 30 vertex-nonvertex twin pairs, 12 of the second fetuses had actual birth weights of 1500 g or less, and all were estimated to weigh less than 1700 g. CONCLUSIONS:The intrapartum sonographic estimate of fetal weight in twin pregnancy by house staff appears reliable, and the accuracy of prediction is similar regardless of presentation, discordance, or actual birth weight greater or less than 1500 g. To avoid vaginal delivery of a persistent nonvertex twin B with a birth weight of 1500 g or less, a sonographic estimate of 1700 g for the second fetus may be adequate. (Obstet Gynecol 1993;82:523-6)