Aim: To assess the effect of time of active pushing (TAP) on neonatal outcome.
Materials and methods: The study population (n=36,432) was taken from a Swedish randomized control trial on intrapartum monitoring, a European Union fetal electrocardiogram trial, and from Mölndal Hospital. After validation of acid-base samples and TAP, 22,812 cases were accepted for analysis.
Results: The median active TAP was 36 min for P0 and 13 min for P≥1 (P<0.001). After adjustments for parity, epidural, labor induction, birth weight, and gender, pushing for 15-29 min (n=6589) relative to pushing for <15 min (n=7264) increased the OR of a cord artery pH of <7.00 to 3.20 (95% CI 1.7-6.0), and that of a base deficit in extracellular fluid of >12 mmol/L to 3.5 (95% CI 1.3-9.0). The group with a cord artery pH of <7.00 had a longer TAP than the group with pH≥7.00: median (5th-95th percentile), 38 (9-107) min vs. 23 (5-87) min, P<0.001. The probability of a spontaneous vaginal delivery decreased significantly with every subsequent increase of 30 min in TAP (P<0.05).
Conclusion: The risks of severe acidemia, metabolic acidosis, and deteriorated neonatal outcome gradually increased with the length of TAP (>15 min), while the probability of a spontaneous vaginal delivery decreased with the duration of pushing. We suggest active physiological evaluation of the labor progress together with continuous electronic fetal monitoring during pushing irrespective of guideline thresholds.