Multiple Gestations

This chapter deals with multiple gestations. It provides the background information of the disease, and discusses its prevention, diagnosis, treatment, and prognosis. Twin gestation refers to an intrauterine gestation of two fetuses; dizygotic twins occur after ovulation and fertilization of two different oocytes and monozygotic twins result from ovulation and fertilization of one single oocyte, with subsequent division. Ultrasound in the first or early second trimester is essential in diagnosing twin gestation and establishing chorionicity. Twin gestation may be suspected if uterine size measures larger than would be expected for a given gestational age; diagnosis can be confirmed only with ultrasound. Twin pregnancies require increased surveillance to detect signs of preterm labor. Cervical length screening to identify patients at risk for preterm delivery is reasonable in order to optimize outcomes with steroids and magnesium sulfate if preterm delivery is imminent.