The odds of delivering one, two or three extremely low birth weight (< 1000 g) triplet infants: a study of 3288 sets.

The odds of an individual triplet pregnancy to end with neonates weighing < 1000 g (extremely low birth weight [ELBW]) are unknown. We analyzed a nationwide perinatal database collected by Matria Healthcare, Inc. (Marietta, GA) to select from 3288 triplets those weighing 500-1000 g, delivered during the period 1988-2000 in the United States. We counted the number of sets with one, two, and three ELBW neonates and compared the incidence of ELBW infants between the subsets of nulliparas and multiparas. The odds of delivering at least one ELBW infant was significantly higher among nulliparas (1:8) than among multiparas (1:14), Odds Ratio (OR) 1.9, 95% Confidence Interval (CI) 1.9, 2.5. The odds of having at least two ELBW sibs in nulliparas (1:16) is twice higher than in multiparas (1:31), OR 2.0, 95% CI 1.3, 2.9. Nulliparas and multiparas had similar odds of delivering three ELBW infants (1:29 versus 1:40, OR 1.3, 95% CI 0.9, 2.1). Nulliparas are at significantly increased risk of delivering one or two ELBW triplets. This observation is no less than alarming and highlighted by the exceptionally high risk of major neurological deficits reported among ELBW infants.