Increasing uptake of induced labour with birth at 39 weeks, especially in women from more socioeconomically deprived areas and in nulliparous women, could help reduce inequalities in perinatal outcomes, according to UK researchers.
Adverse perinatal outcomes — which included include stillbirths, neonatal deaths, preterm births, and other birth complications — were more common among women from deprived areas and ethnic minorities in England, commented the authors of a study, published in PLOS Medicine. They emphasised that the role of induction of labour in reducing inequalities in obstetric outcomes was "controversial", which was in part, due to insufficient evidence, they pointed out.
There was debate about whether induction of labour with birth at 39 weeks should be offered, based on ethnicity or deprivation in low-risk pregnancies, as a means of reducing inequalities, the authors explained.
Induced Women Had Lower Risk of Adverse Perinatal Outcomes
The study, led by the London School of Hygiene and Tropical Medicine (LSHTM), set out to identify adverse perinatal outcomes associated with induction of labour with birth at 39 weeks compared with expectant management.
The researchers analysed data of all maternal admissions in the English NHS between January 2018 and March 2021. Using the Hospital Episode Statistics (HES) dataset, maternal and neonatal data was linked with neonatal mortality data from the Office for National Statistics. They measured the association between induction of labour at 39 weeks and adverse perinatal outcomes in low-risk pregnancies. Over half a million (501,072) women with low-risk pregnancies who had not yet given birth at 39 weeks were included in the analysis, with 9.5% (47,352) of these having had induction of labour at 39 weeks.
The investigation found that women who were induced and gave birth at 39 weeks had a lower risk of adverse perinatal outcomes compared with women who had expectant management and gave birth after 39 weeks. Approximately 3.3% of births in the induction group and 3.6% of births in the expectant management group had an adverse perinatal outcome. After adjustment, the researchers found a small benefit from induction of labour in low-risk pregnancies — the risk difference being −0.28% and −0.12%. The authors estimated that overall, "360 inductions are needed to avoid one adverse perinatal outcome".
The risk difference was found to vary according to socioeconomic background, from 0.38% in the least deprived to −0.48% in the most deprived national quintile, highlighted the authors. It also varied by parity, with a risk difference of −0.54% in nulliparous women and −0.15% in multiparous women.
There was no statistically significant evidence that risk differences varied according to ethnicity, said the authors.
Improved Data Collection Needed to Corroborate Findings
"An increased uptake of induction of labour with birth at 39 weeks, especially in women from more socioeconomically deprived areas and in nulliparous women, may help reduce inequalities in perinatal outcomes," the authors concluded.
Some limitations to their investigation were acknowledged, including the absence of additional confounding factors such as smoking, BMI, and the indication for induction in the HES datasets, which might mean that some higher risk pregnancies were included.
Thus, they pointed out, the greater benefit from induction of labour with birth at 39 weeks in women from more socioeconomically deprived areas might be "explained by an increased prevalence of maternal risk factors".
Asma Khalil, professor of obstetrics and maternal foetal medicine at St George's Hospital, London, and study co-author, said that "improved" collection of routine data on the indication for induction and the presence of risk factors was required to "corroborate" the role that induction of labour at 39 weeks in women with a low-risk pregnancy could play in reducing inequalities in risk of adverse perinatal outcomes.
Co-author Dr Ipek Gurol-Urganci, PhD, from the LSHTM, emphasised that the study highlighted an urgent need for detailed, accurate, and complete data from each maternity unit, collected at national level, especially about the indications of induction of labour, "so that we get an even better understanding of the role that induction of labour can play in improving perinatal outcomes".