Objective: To determine the incidence and trends of twinning in the United States and to review the medical and economic effects of twin versus singleton gestations.
Methods: Pertinent and recent studies on twin gestations were obtained through a MEDLINE database search of the English language between December 1987 and December 1999. Data from the 1995-1996 National Center for Health Statistics were also used to compare gestational age at delivery, fetal growth restriction, and perinatal mortality for twin and singleton gestations. Studies that have evaluated perinatal risks in relation to advanced reproductive technology also were reviewed and summarized. The economic implications of twinning from a societal perspective and infant quality of life issues of twins compared with singleton gestations are reviewed.
Results: Due to delayed childbearing and increased use of reproductive technologies, the incidence of twin gestations in the United States has been increasing. Twin pregnancies have a higher risk of complications, including pregnancy-induced hypertension, anemia, antepartum and postpartum hemorrhage, and maternal mortality. In addition, twin infants are more likely to deliver preterm, have low birth weight and greater perinatal mortality rates. These outcomes influence health care costs and quality of life for both parents and children.
Conclusions: Women carrying twin fetuses are at increased risk for perinatal and obstetric complications. The increased perinatal risks that accompany twin fetuses may be partly due to the increasing use of advanced reproductive technologies. The economic burdens, as well as the potential for decreased quality of life among twins, needs careful evaluation.