Maternal and perinatal complications by day of gestation after spontaneous labor at 40-42 weeks of gestation.

Objective: To evaluate pregnancy outcome after spontaneous labor by day of gestation between 40(+0) and 41(+6) weeks of gestation.

Design: Evaluation of prospectively collected labor ward data.

Setting: University Hospital, Denmark.

Population: Unselected consecutive cohort of 14 678 spontaneously starting deliveries between 280 and 293 days of gestation during the years 2000-2006.

Methods: Data were registered in a computer program after each delivery by a midwife and the entries further evaluated by a specialist in obstetrics. Complication rates were compared using Fisher's exact test.

Main Outcome Measures: Maternal complication rates for each gestation day, including cesarean delivery, maternal blood transfusion, episiotomy, operative vaginal delivery, third and fourth degree perineal lacerations and perinatal morbidity.

Results: The cesarean delivery rate increased from 6% on day 280 to 11% on day 293. Cesarean delivery increased from 40 to 41 weeks gestation (7.3 vs. 9.5%, p<0.005), as did maternal transfusion (0.5 vs. 1.2%, p<0.001) and cesarean section on the indication fetal distress (1.5 versus 2.4%, p<0.005), but perineal lacerations did not. Likewise, there was an increase in episiotomy rates (3.0 vs. 3.5%, p=0.08), operative vaginal delivery (5.8 vs. 6.5%, p=0.07) and admission to neonatal intensive care (1.4 versus 2.0%, p=0.009), but no increase in 5 minute Apgar scores <7 or low umbilical artery acid-base values.

Conclusions: Deliveries starting spontaneously in an unselected cohort showed an increase in maternal complications, meconium-stained amniotic fluid and admission to the neonatal intensive care unit.