Optimal Timing of Term Births by Maternal Region of Birth: Elective Induction of Labor Compared to Expectant Management in Victoria, Australia.

Induction of labor (IOL) has been suggested to mitigate the elevated risks of perinatal mortality in migrant women. The aim was to estimate the rates of perinatal mortality, cesarean, instrumental birth, and admission to the special care nursery or neonatal intensive care unit (SCN/NICU) for births following IOL compared to expectant management at 37-41 weeks' gestation by maternal region of birth. A population-based retrospective cohort of all vertex singleton, uncomplicated pregnancies, 37 to 41 weeks' gestation in Victoria, Australia, from 2012 to 2019. Perinatal mortality rates were reported by region of birth. Multivariable log binomial regression models were used to estimate the association between outcomes and IOL compared to expectant management by region of birth. There was no improvement in the perinatal mortality rate with IOL at any gestation for non-Australian region of birth groups. IOL at 38 weeks was associated with an increasing risk of cesarean birth for Australian, New Zealand, Oceanic, African, and South-East Asian and East Asian-born women, with a higher risk for South Asian-born women at 39 weeks. Compared to expectant management, the risk of instrumental birth was similar at each gestational week for Australian-born women; whereas for African and South Asian-born women, the risk was highest at 37 weeks; for Oceanic-born women, this occurred at 38 weeks. An inverse relationship between the week of IOL and admission to the SCN/NICU was observed for all births. IOL was associated with an increased risk of cesarean birth, instrumental birth, and admission to the SCN/NICU in many situations without an improvement in perinatal mortality rates.