The role of confounding in the association between pregnancy complications and subsequent preterm birth: a cohort study

Dunne, Jennifer
Tessema, Gizachew
Pereira, Gavin

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Publication date

January 2022

DOI

10.1111/1471-0528.17007

Publisher

WILEY

Abstract

Objective: To estimate the degree of confounding necessary to explain the associations between complications in a first pregnancy and the subsequent risk of preterm birth. Design: Population-based cohort study. Setting: Western Australia. Population: Women (n = 125 473) who gave birth to their first and second singleton children between 1998 and 2015. Main outcome measures: Relative risk (RR) of a subsequent preterm birth (<37 weeks of gestation) with complications of pre-eclampsia, placental abruption, small-for-gestational age and perinatal death (stillbirth and neonatal death within 28 days of birth). We derived e-values to determine the minimum strength of association for an unmeasured confounding factor to explain away an observed asso...