Apgar score and perinatal death after one previous caesarean delivery

OBJECTIVE: To assess the impact of the indication for a previous caesarean section on the outcome of a subsequent delivery. DESIGN: Population-based cohort study. SETTING: Sweden. POPULATION: Women with two deliveries between 1987 and 2007 identified using the Swedish Medical Birth Registry. METHODS: The outcome of 69 133 pregnancies after one caesarean section was compared with the outcome of 487 610 pregnancies following one vaginal delivery. The indication for the first caesarean section was estimated using a new hierarchical system based on information from birth records. MAIN OUTCOME MEASURES: Perinatal death, low Apgar score (less than seven at 5 minutes). RESULTS: Infants of women with one previous caesarean section were at increased risk of low Apgar score compared with infants of women with one previous vaginal delivery (OR, 2.0; 95% CI, 1.9-2.1). The risk estimate was reduced when adjustment for maternal and fetal/infant characteristics was made (OR, 1.6; 95% CI, 1.5-1.8). The corresponding crude and adjusted odds ratios for perinatal death were 1.6 (95% CI, 1.4-1.7) and 1.1 (95% CI, 1.0-1.2), respectively. The infant outcome of the delivery after one caesarean section was mainly dependent on the indication for the first-delivery caesarean section and, when no medical indication was present, no increase in risk was detected. CONCLUSIONS: Infants of women with one previous caesarean section were at increased risk of low Apgar score and/or perinatal death compared with infants of women with one previous vaginal delivery. The results suggest that medical conditions, not the previous caesarean section per se, contributed to the increase in risk.