Doctors refer to these complications as severe maternal morbidity (SMM), which can include heart attack, heart failure, sepsis, and hysterectomy. In the UK, SMM has almost doubled from 0.9% of deliveries in 2009 to 1.7% in 2018, suggesting that broadening access to epidural analgesia for all women, and particularly those at greatest risk of SMM, could improve maternal health.

Epidural analgesia is recommended for women with known risk factors for SMM, such as obesity, certain underlying conditions, or having more than one baby. These women are said to have a ‘medical indication’ for epidural analgesia in labour. Women delivering prematurely also carry a higher risk of SMM.

Some research suggests that epidural analgesia in labour may reduce the risk of SMM, though evidence is limited. To address this, a team from the University of Glasgow in collaboration with the University of Bristol set out to determine the effect of labour epidural on SMM and explore whether this was greater in women with a medical indication for epidural in labour, or those in preterm labour.

Their findings are based on Scottish National Health Service data for 567,216 mothers in labour (average age 29, 93% white) delivering vaginally or via unplanned caesarean section in Scotland between 2007 and 2019.

Medical records were used to identify any of the 21 conditions defined as SMM by the US Centers for Disease Control and Prevention or a critical care admission occurring at any point from date of delivery to 42 days after giving birth.

Factors such as mother’s age, ethnicity, weight, smoking history and pre-existing conditions, as well as birth location and gestational age at birth were also taken into account.

Of the 567,216 women, 125,024 (22%) had an epidural in labour and SMM occurred in (4.3 per 1000 births).

Having an epidural was associated with a 35% reduction in SMM in all women in the study. Greater reductions were seen among women with a medical indication for epidural (50% risk reduction) compared to those without (33% risk reduction) and in women delivering preterm (47% risk reduction) compared to term or post-term (no evidence of reduced risk). Notably, among the 77,439 women in the study who were at higher risk of severe maternal morbidity, only 19,061 (24.6%) received an epidural.

Possible explanations for benefits of epidural on SMM include closer monitoring of women with an epidural, blunting of physiological stress responses to labour, avoidance of the need for spinal or general anaesthesia for caesarean section, and faster escalation to definitive obstetric interventions. The relatively low use of epidural, particularly in those with clinical indications may reflect women not fully understanding the potential benefits, as it is women’s choice that determines whether or not they have an epidural

This is an observational study so no firm conclusions can be drawn about cause and effect, and the authors acknowledge several limitations that may have influenced their results. The study also involved predominantly white women delivering in Scotland, which may limit generalisability to ethnically diverse populations or different healthcare settings, they add.

However, this was a large, well-designed study that reflects contemporary obstetric and anaesthetic practices, and results were similar after further analyses, supporting the robustness of the findings. 

As such, the authors conclude: “These findings substantiate the current practice of recommending epidural analgesia during labour to women with known risk factors, underscores the importance of ensuring equitable access to such treatment. Taken together with previous research by the same group of lower use of labour epidural in women from more deprived areas and of non-white European ethnicity, they highlight the importance of supporting women from diverse backgrounds to be able to make informed decisions relating to epidural analgesia during labour.”

These findings suggest that epidural analgesia is a viable protective option for at-risk pregnancies and decision makers should consider this new benefit to improve maternal health outcomes, say researchers in a linked editorial. They point to the importance of understanding the mechanisms behind this protective effect and recognising inequalities in uptake, with much lower rates in, for example, minority ethnic groups and socioeconomically deprived communities. With this in mind, these findings “might serve as a catalyst for initiatives aimed at improving equitable access to epidural analgesia during labour, potentially mitigating SMM and improving maternal health outcomes across diverse socioeconomic and ethnic backgrounds,” they conclude.

Professor Rachel Kearns, lead author of the study from the University of Glasgow, said: “Our research reveals that epidural analgesia during labour is linked to a substantial decrease in severe maternal health complications. This finding underscores the need to ensure access to epidurals, particularly for those who are most vulnerable – women facing higher medical risks or delivering prematurely.

“By broadening access and improving awareness, we can significantly reduce the risk of serious health outcomes and ensure safer childbirth experiences.”

Deborah Lawlor, Professor of Epidemiology at the University of Bristol and one of the study's authors, added: “That women, and their partners, have control over their treatment during pregnancy, including the use of an epidural during labour, is important. It is also important that women who would benefit from an epidural to prevent them becoming seriously ill, are provided with easy to understand information to help them make an informed decision.”

Paper

'Epidural analgesia during labour and severe maternal morbidity: population based study' by R J Kearns et al. in The BMJ.
Editorial: Unlocking maternal health: labour epidurals and severe morbidity