Caesarean birth and risk of subsequent preterm birth: a retrospective cohort study

Carolina Williams, Rosalyn Fong, Sarah Murray, Sarah J Stock

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

OBJECTIVE: To determine the risk of spontaneous and medically indicated preterm birth associated with mode of birth in previous term born pregnancy.

DESIGN: Retrospective cohort study SETTING: Two UK maternity units POPULATION OR SAMPLE: 16340 women with first two consecutive singleton births and the first birth at term METHODS: Retrospective cohort study using routinely collected clinical data.

MAIN OUTCOME MEASURES: Incidence of spontaneous preterm birth and medically indicated preterm birth less than 37 weeks gestation after term birth, in relation to mode of birth in first pregnancy. Subgroup analysis on cervical dilatation at the time of first caesarean birth.

RESULTS: Compared to vaginal birth, emergency caesarean birth at full dilatation was associated with an increase in spontaneous preterm birth (2.3% vaginal birth versus 4.5% full dilatation caesarean; adjusted Odds Ratio [aOR] 3.29 (95% Confidence Interval [CI] 2.02-5.13, p<0.001). Elective, emergency caesarean <4cm, and emergency caesarean 4-9 cm were associated with increased medically indicated preterm birth (0.8% vaginal births versus 1.9 % elective caesarean, 3.3% <4 cm caesarean, 1.3% 4-9 cm caesarean; aOR 2.30 [1.19-4.15], p=0.009; 4.68 [2.98-7.24], p<0.001; and 2.43 [1.43-4.00], p=0.001 respectively).

CONCLUSIONS: Term caesarean in the first stage of labour or performed prelabour is associated with medically indicated preterm birth. Term caesarean in the second stage of labour is associated with spontaneous preterm birth.

Original languageEnglish
JournalBJOG: An International Journal of Obstetrics and Gynaecology
Early online date12 Oct 2020
Publication statusE-pub ahead of print - 12 Oct 2020


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