Adverse pregnancy, birth, and infant outcomes in twins: effects of maternal fertility status and infant gender combinations; the Massachusetts Outcomes Study of Assisted Reproductive Technology

Background It is unknown whether the risk of adverse outcomes in twin pregnancies among subfertile women, conceived with and without in vitro fertilization, differs from those conceived spontaneously. Objective We sought to evaluate the effects of fertility status on adverse perinatal outcomes in twin pregnancies on a population basis. Study Design All twin live births of ≥22 weeks’ gestation and ≥350 g birthweight to Massachusetts resident women in 2004 through 2010 were linked to hospital discharge records, vital records, and in vitro fertilization cycles. Women were categorized by their fertility status as in vitro fertilization, subfertile, or fertile, and by twin pair genders (all, like, unlike). Women whose births linked to in vitro fertilization cycles were classified as in vitro fertilization; those with indicators of subfertility but without in vitro fertilization treatment were classified as subfertile; all others were classified as fertile. Risks of 6 adverse pregnancy outcomes (gestational diabetes, pregnancy hypertension, uterine bleeding, placental complications [placenta abruptio, placenta previa, and vasa previa], prenatal hospitalizations, and primary cesarean) and 9 adverse infant outcomes (very low birthweight, low birthweight, small-for-gestation birthweight, large-for-gestation birthweight, very preterm [