Intrauterine growth of triplets as estimated from liveborn birth weight data.

This study was conducted to estimate intrauterine growth of triplet pregnancies from liveborn birth weights. During the years 1975-92, 109 sets of triplets were born at our hospital. Ten sets were excluded because of either major fetal anomalies or fetal death of one or more of the fetuses. The remaining 99 sets of triplets consisted of 297 newborns that were weighted immediately after birth. The mean birth weight was plotted against gestational week. The estimated intrauterine growth of triplets, in contrast to singletons, exhibited neither an acceleration phase during the third trimester, nor a flattening of the growth curve during the last few weeks of the third trimester. The mean birth weight of triplets was slightly below the 10th centile for singletons at 38 weeks' gestation or later. We conclude that the growth of triplet fetuses as estimated from liveborn birth weights is slower than that of singletons. The diagnosis of intrauterine growth retardation in triplet pregnancies should be based on growth curves to be devised for triplet pregnancies.