Placental ratio and risk of velamentous umbilical cord insertion are increased in women with placenta previa.

The purpose of this study was to explore the maternal risk profile and obstetric outcome in pregnancies affected by placenta previa. Retrospective case-control study involved all women (93 [0.37%] women with diagnosed placenta previa and 24,857 unaffected controls) who gave birth to singleton infants at Kuopio University Hospital between the years 1989 and 2000. Grand multiparity, infertility problems, and advanced maternal age were independent risk factors of placenta previa, with adjusted relative risks of 5.8, 3.7, and 2.4, respectively. Most women with placenta previa (88.2%) underwent cesarean delivery before term. They also more often had velamentous umbilical cord insertion (7.5%) and higher placental-to-birthweight ratios than the controls. Placenta previa was associated with risks of preterm delivery, low birthweight infants, and need for neonatal intensive care, at odds ratios of 27.7, 7.4, and 3.4, respectively. In conclusion, placenta previa is an infrequent pregnancy complication associated with multiparity, advanced maternal age, infertility problems, elevated placental ratio, and velamentous umbilical cord insertion.