Effect of maternal height on gestational age and birth weight in nulliparous mothers of triplets with a normal pregravid body mass index.

OBJECTIVE: To study the effect of maternal height on gestational age and birth weight of triplets born to nulliparous women with a normal pregravid body mass index (BMI). STUDY DESIGN: A 19882000 prospective cohort of 1,219 U.S. live-born triplets was evaluated. Patients were grouped into stature categories of 5-cm intervals. Mean values for BMI, height, maternal age, gestational age at birth, total triplet birth weight and frequencies of births at < 28 weeks and with very low birth RESULTS: Maternal heights were normally distributed (mean, 165.2 +/- 6.2 cm). We found a significant positive correlation (R-2 =.95), different from a zero slope (P<.01), between mean total triplet birth weight and height category. Nulliparous women who were taller than 165 cm had age, BMI and gestational age characteristics similar to those of their shorter counterparts but delivered significantly heavier triplets and were at significantly lower risk of delivering very-low-birth-weight triplets. CONCLUSION: Taller women are more likely to deliver heavier triplets and are at lower risk of delivering very-low-birth-weight triplets. This information should be included in counseling women with the potential of conceiving triplets.