[Birth weight and height characteristics of triplets].

Objective: This study was conducted to assess the birth weight and height in triplets, and to identify associated factors.

Method: The subjects were 371 sets of triplets (1,113 triplets), who were born after 1986. Data on birth weight, birth height, gender, birth order, mode of delivery, gestational age, maternal weight gain at delivery, and infertility treatment were obtained. Pregravidic body mass index (BMI) was computed to evaluate maternal physique.

Results: Mean triplet birth weight was 1,763.3 +/- 420.6 g and mean birth height was 42.2 +/- 3.36 cm. Overall, 96% were low birth weight newborn, 24.4% were very low birth weight newborn, and 4.9% had less than 1,000 g weight. The triplet birth weight was significantly associated with gender (male > female), sex combination (opposite-sexed sets > same-sexed sets), mode of delivery (vaginal delivery > caesarean section), and pregravidic body mass index (BMI) (more than 26.0 kg/m2 > less than 19.8 kg/m2). There was a significant correlation coefficient between maternal weight gain at delivery and birth weight. The triplet birth height was significantly associated with gender (male > famale), sex combination (opposite-sexed sets > same-sexed sets), and pregravidic BMI (more than 26.0 kg/m2 > less than 19.8 kg/m2). Moreover, the birth height was associated with maternal weight gain at delivery and infertility treatment.

Conclusion: The birth weight and birth height in triplets are much lower than those for singletons and twins. Triplet birth weight is associated with gender, birth order, pregravidic body mass index, mode of delivery, and maternal weight gain at delivery, taking into account gestational age. Birth height is associated with gender, pregravidic body mass index, and infertility treatment.