BMJ Open (2019) 9 (5), 2019. doi: 10.1136 / bmjopen-2018 - 028136 Genital Tract Abnormalities Structural abnormalities of the uterus and cervix (eg, uterine septum, bicornuate uterus) make the following more likely: Spontaneous abortion during the 2nd trimester Fetal malpresentation Preterm labor or delivery Dysfunctional labor The need for cesarean delivery Uterine fibroids uncommonly cause placental abnormalities (eg, placenta previa), preterm labor, and recurrent spontaneous abortion.