MATERNAL WEIGHT-GAIN PATTERNS AND BIRTH-WEIGHT OUTCOME IN TWIN GESTATION

Objective: To evaluate the association between maternal weight gain pa tterns, based on pregravid body mass index (BMI) and birth weight outc ome in twins, and to make specific recommendations for maternal weight gain during twin gestation. Methods: One hundred eighty-nine twin pre gnancies were reviewed retrospectively. Weekly rates of maternal weigh t gain before 20 weeks, from 20 weeks to delivery, and for total gesta tion were calculated. Thresholds of weekly maternal weight gain were d etermined for underweight and normal-weight women. Results: In underwe ight women, a higher weekly rate of gain before 20 weeks was associate d with the birth of both twins weighing at least 2500 g (1.13 versus 0 .70 lb/week, P = .017), when compared with mothers of at least one twi n weighing less than 2500 g. A higher rate of weight gain from 20 week s to delivery was associated with the delivery of twins weighing at le ast 2500 g in both underweight (1.92 versus 1.29 lb/week, P = .031) an d normal weight (1.63 versus 1.29 lb/week, P = .046) women. No signifi cant differences in weight gain patterns were found between overweight women delivering twins weighing less than 2500 g or at least 2500 g. A weekly rate of gain from 20 weeks' gestation to delivery of at least 1.75 lb/week in underweight women and at least 1.50 lb/week in normal -weight women was associated with the birth of both twins weighing at least 2500 g. After controlling for other potential determinants of bi rth weight, the threshold of 1.75 lb/week in underweight women showed a trend toward significance as an independent predictor of both twins weighing at least 2500 g (P = .06). Conclusion: Certain maternal weigh t gain patterns during twin pregnancy are associated with the birth of each twin weighing at least 2500 g. As with singletons, recommendatio ns for maternal weight gain during twin pregnancy can be based on preg ravid BMI.