Trial of labour after caesarean section and the risk of neonatal and infant death: a nationwide cohort study

BACKGROUND: Caesarean section (CS) rates are increasing worldwide and as a result repeat CS is common. The optimal mode of delivery in women with one previous CS is widely debated and the risks to the infant are understudied. The aim of the current study was to evaluate if women with a trial of labour after caesarean (TOLAC) had an increased odds of neonatal and infant death compared to women with an elective repeat CS (ERCS). METHODS: A population register-based cohort study was conducted in Denmark between 1982 and 2010. All women with two deliveries [in which the first was a CS, and the second was an uncomplicated, term delivery (n = 61,626)] were included in the study. Logistic regression models were used to report adjusted odds ratios (AOR) and 95% confidence intervals (CI) of the odds of death according to mode of delivery. The main outcome measures were neonatal death (early and late) and infant death. RESULTS: Women with a TOLAC had an increased odds of neonatal death (AOR 1 · 87, 95% CI 1 · 12 to 3 · 12) due to an increased risk of early neonatal death (AOR 2 · 06, 95% CI 1 · 19 to 3 · 56) and no effect on late neonatal death (AOR 0 · 97, 95% CI 0 · 22 to 4 · 32), or infant death (AOR 1 · 12, 95% CI 0 · 79 to 1 · 59) when compared to the reference group of women with an ERCS. There was evidence of a cohort effect as the increased odds of neonatal death (AOR 3 · 89, 95% CI 1 · 33 to 11 · 39) was most significant in the earlier years (1982–1991) and gradually disappeared (AOR 1 · 01, 95% CI 0 · 44 to 2 · 31) in the later years (2002–2010). CONCLUSIONS: Although an increased risk of neonatal death was found in women with a TOLAC, there was evidence of a cohort effect, which showed this increased odds disappearing over time. Advances in modern healthcare including improved monitoring and earlier detection of underlying pregnancy complications may explain the findings. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12884-017-1255-2) contains supplementary material, which is available to authorized users.