Contraction frequency and acidemia at birth: A case-control study.

Increasing contraction frequency is incrementally associated with fetal acidemia. Although an increased risk of acidosis is evident at contraction frequencies as low as five, such frequencies are common while acidemia is uncommon, implying a poor positive predictive value. A contraction frequency of more than five is associated with acidemia in both spontaneous and oxytocin-augmented labor, and even when the fetal heart trace is normal.