Does regular exercise in pregnancy influence duration of labor? A secondary analysis of a randomized controlled trial

Objectives: To study effects of regular physical exercise in pregnancy on duration of the active phase of labor and the proportions of women with prolonged active second stage.

Design: A two-armed, two-center randomized controlled trial.

Setting: St. Olavs Hospital, Trondheim University Hospital and Stavanger University Hospital.

Population: A total of 855 women were randomized to intervention or control groups.

Methods: The intervention was a 12-week exercise program, including aerobic and strengthening exercises, conducted between the 20th and 36th week of gestation. One weekly group session was led by physiotherapists and home exercises were encouraged twice a week. Controls received standard antenatal care.

Main outcome measures: The duration of active phase of labor and number of prolonged second stage deliveries (active pushing > 60 min). We also studied labor outcomes. Supplementary analyses were done in a subgroup of nulliparous women with a singleton cephalic fetus and spontaneous start of term delivery.

Results: Duration of labor was similar in the two groups, and there were no differences in labor outcomes. In a subgroup analysis the duration of active second stage labor was shorter in the control group (p = 0.01).

Conclusions: Regular physical exercise during pregnancy did not influence duration of the active phase of labor or the proportion of women with prolonged active second stage.