Pregnancy Characteristics

Plural gestations, which account for 2-3% of all live births, carry a considerable risk for preterm birth and account for 15-20% of all preterm births. Nearly 60% of twins are born preterm with 40% of twins experiencing spontaneous preterm birth or PPROM before 37 weeks of gestation.53 In the case of twins and higher order plural gestations, uterine overdistension, resulting in contractions and PPROM is thought to be the most frequent cause of spontaneous preterm delivery. Placental abruption and/or placental previa as well as unrelated vaginal bleeding earlier in pregnancy is associated with higher rates of preterm birth.50 Extremes in the volume of amniotic fluid—either polyhydramnios or oligohydramnios—are associated with preterm labor and PPROM.34 Finally, uterine or cervical anatomical anomalies, such as uterine septa and/or bicoronate uterus, are associated with higher rates of preterm delivery.54