Recurrence of preterm birth and perinatal mortality in northern Tanzania: registry-based cohort study

Michael J. Mahande, Anne K. Daltveit, Joseph Obure, Blandina T. Mmbaga, Gileard Masenga, Rachel Manongi and Rolv T. Lie
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Objectives: To estimate the recurrence risk of preterm delivery and estimate the perinatal mortality in repeated preterm deliveries.

Methods: Prospective study in Tanzania of 18 176 women who delivered a singleton between 2000 and 2008 at KCMC hospital. The women were followed up to 2010 for consecutive births. A total of 3359 women were identified with a total of 3867 subsequent deliveries in the follow-up period. Recurrence risk of preterm birth and perinatal mortality was estimated using log-binomial regression and adjusted for potential confounders.

Results: For women with a previous preterm birth, the risk of preterm birth in a subsequent pregnancy was 17%. This recurrence risk was estimated to be 2.7-fold (95% CI: 2.1–3.4) of the risk of women with a previous term birth. The perinatal mortality of babies in a second preterm birth of the same woman was 15%. Babies born at term who had an older sibling that was born preterm had a perinatal mortality of 10%. Babies born at term who had an older sibling who was also born at term had a perinatal mortality of 1.7%.

Conclusion: Previous delivery of a preterm infant is a strong predictor of future preterm births in Tanzania. Previous or repeated preterm births increase the risk of perinatal death substantially in the subsequent pregnancy.