1. Long, strong contractions. These can be something that happens without interference, but pitocin can cause this also.
2. If the mom is on her back, this presses on an artery in mom that can then cause hypotension. This then leads to a decrease in the amount of oxygen that baby is able to receive.
3. An epidural could also cause hypotension in mom which can lead to a decrease in oxygen for baby.
4. Placenta previa, which is where the placenta is covering the cervix, can lead to hemorrhage in mom, and thus decreased oxygen for baby.
5. Abruption placentae is where part of the placenta pulls away from the uterine wall, can lead to hemorrhage.
6. Some diseases that can cause poor perfusion of the placenta are: hypertension, pre-eclampsia, collagen vascular disease, diabetic vasculopathy disease, and prolonged pregnancy.
Obstetrics: Normal and Problem Pregnancies, 5th ed. Gabbe et al.
Fanaroff and Martin's Neonatal-Perinatal Medicine, 8th ed. Martin et al.