Weight of babies conceived in vitro.

Recent studies suggested that infants delivered after in vitro fertilization and embryo transfer IVF-ET had low birth weights. To assess further the relationship between birth weight and EGA in these offspring, a review was made of all infants delivered at our institution from May 1, 1983 to July 15, 1986. Forty-five infants in 39 deliveries were identified. Seventeen of 37 (46%) were delivered vaginally, 20 by cesarean section. Forty-two infants were delivered at term (after 36 weeks). The six sets of twins delivered at 254 +/- 7 days (mean, 36 weeks). Eighteen of 39 deliveries (46%) delivered at or beyond 40 weeks EGA. The mean weight at delivery for the term infants was 3225 +/- 90 g. Thirty-eight infants were size appropriate for dates as assessed by the Lubchenco scale, while the weight in the remaining seven infants exceeded the 90th percentile for their gestational age. We conclude that infants conceived through IVF-ET are not predisposed per se to a low birth weight or delivery at an early gestational age. However, prior studies suggesting lower birth weights for IVF infants may have resulted in part from early delivery due to patient pressure and anxiety.