[Antenatal complications in triplet pregnancies and birth weights of triplets compared with those of twins].

A mailed questionnaire survey was conducted on 96 mothers of triplets to study antenatal complications in triplet pregnancies and birth weights of triplets, and compared to 122 controls recruited from mothers of twins. The following results were obtained. 1) Antenatal complications occurred in approximately 80% of both triplet and twin pregnancies. In the triplet pregnancies the incidence of toxemia of pregnancy and anemia was 25.0% and 47.9%, respectively. There was no significant difference in the incidence of antenatal complications, toxemia of pregnancy and anemia between triplet and twin pregnancies. On the other hand, the incidence of preterm labor and threatened miscarriage was higher in triplets (70.8% and 34.4% respectively) than in twin pregnancies (45.9% and 12.3% respectively). 2) The mean birth weight was 1831.7 g for each individual triplet and 5495.0 g for each triplet set. In triplets, 94.7% were low in birth weight (< 2500 g). 3) The antenatal complications of preterm labor and threatened miscarriage in triplet pregnancies have increased since 1990 in Japan. The frequency of toxemia of pregnancy and anemia did not particularly change significantly during the surveyed years. However, mean birth weight for each individual triplet showed a tendency to decrease from year to year (1978-1989, 1934.5 g; 1990-1991, 1900.3 g; 1992-1993, 1741.1 g).