Multiple gestation: Reflections on epidemiology, causes. and consequences

Multiple births (of all orders) increased in epidemic proportions in the ye ars 1971-1997. Twins increased 53%, 32%, 31%, and 83% in white, Afro-Americ an, Native American and Mexican American women, respectively. Triplet, quad ruplet, and quintuplet+ births increased >400%, >1,100%, and >500%, respect ively, in the same years. The principal causes of these changes are related to the increasing age of the maternal cohort and an increasing incidence o f fertility-inhibiting diseases and conditions in association with advancin g maternal age. Major immediate consequences of these changes include dispr oportionately large numbers of infants born at <33 weeks' gestation (1.7% f or singletons vs. 41.2% for triplets) and at <1,500 g birth weight (1.1% fo r singletons vs. 31.9% for triplets). Additional short-term consequences in clude an almost 2,000% increase in infant deaths (per 1,000 live births) am ong triplets compared with singletons (190.4 vs. 11.2). Long-term risks inc lude a 300% increase in the relative risk of handicap in triplets compared with singletons (2.9 vs. 1.0), and a 650% increase in the rate of cerebral palsy per 1,000 live births In triplets compared with singletons (26.6 vs. 1.6). Peripartum costs relate to prematurity rather than plurality, as do l ifetime survivorship costs, which relate to morbidities and subsequent heal th-related problems.