Risk factor | Singleton gestations | Twin gestations |
Strength | RR/OR | Strength | RR/OR |
Acute etiology |
Abdominal trauma/accidents | +++ | | | |
Cocaine or other drug abuse (eg, methamphetamine) | +++ | 5.0 to 10.0 | | |
Polyhydramnios | ++ | 2.0 to 3.0 | ++ | 1.7 |
Obstetric/medical risk factors |
Chronic hypertension | ++ | 1.8 to 5.1 | | |
Preeclampsia/pregnancy-induced hypertension | ++ | 0.4 to 4.5 | | |
Eclampsia | +++ | 3.0 to 5.5 | ++ | 1.6 to 2.0 |
Prelabor rupture of membranes | ++ | 1.8 to 5.1 | ++ | 1.5 to 2.5 |
Chorioamnionitis | ++ | 2.0 to 2.5 | ++ | 1.7 |
Short umbilical cord | ++ | 1.33 to 1.96 | | |
Previous ischemic placental disease |
Preeclampsia | ++ | 1.5 | | |
Fetal growth restriction/small for gestational age infant | ++ | 1.4 | | |
Previous abruption | ++++ | 8.0 to 12.0 | | |
Sociodemographic/behavioral |
Older maternal age | + | 1.1 to 1.3 | + | 1.1 to 1.4 |
Multiparity | + | 1.1 to 1.6 | + | 1.1 to 1.7 |
Smoking during pregnancy | ++ | 1.4 to 2.5 | ++ | 1.7 |