Mortality and morbidity among twins: recent observations from the United States.

The increasing number of twin (and higher order) births is a matter of national concern for two reasons: First, the differential rates of preterm (< 37 weeks) delivery and low birthweight (< 2,500g) among twins compared to singletons; and second, the inordinate contribution of these infants to overall infant mortality, morbidity and long-term handicap. Data from all births in the U.S. during 1987 and 1988 was used to calculate distribution frequencies for gestational age at delivery, and birthweight, as well as mortality and handicap rates and the corresponding relative risks of these latter events for twins compared to singletons. A suggestion for improvement in the mortality and handicap rates and reduced costs among survivors is presented. This proposal is based upon data from the singleton and twin literature and the use of the prenatal invervention of adequate maternal nutrition during the pregnancy.