Risk factors and newborn outcomes associated with maternal deaths in the UK from 2009 to 2013: a national case-control study

Objectives: To identify the risk factors for and adverse newborn outcomes associated with maternal deaths from direct and indirect causes in the UK.

Design: Unmatched case-control analysis.

Setting: All hospitals caring for pregnant women in the UK.

Population: Comprised 383 women who died (cases) from direct or indirect causes from 2009 to 2013 (Confidential Enquiry into Maternal Deaths in the UK) and 1516 women who did not have any life-threatening complications during pregnancy and childbirth (controls) obtained from UK Obstetric Surveillance System (UKOSS).

Methods: Multivariable regression analyses were undertaken to examine potential risk factors, their incremental effects, and adverse newborn outcomes associated with maternal deaths.

Outcomes: Odds ratios associated for risk factors for maternal death and newborn outcomes (stillbirth, admission to neonatal intensive care unit [NICU], early neonatal death) and incremental risk.

Results: Seven factors, of 13 examined, were independently associated with increased odds of maternal death: pre-existing medical comorbidities (adjusted odds ratio [aOR] 8.65; 95% CI 6.29-11.90), anaemia during pregnancy (aOR 3.58; 95% CI 1.14-11.21), previous pregnancy problems (aOR 1.85; 95% CI 1.33-2.57), inadequate use of antenatal care (aOR 46.85; 95% CI 19.61-111.94), substance misuse (aOR 12.21; 95% CI 2.33-63.98), unemployment (aOR 1.81; 95% CI 1.08-3.04) and maternal age (aOR 1.06; 95% CI 1.04-1.09). There was a four-fold increase in the odds of death per unit increase in the number of risk factors. Odds of stillbirth, admission to NICU and early neonatal death were higher among women who died.

Conclusion: This study reiterates the need for optimal care for women with medical comorbidities and older age, and the importance of adequate antenatal care. It demonstrates the existence of socio-economic inequalities in maternal death in the UK.

Tweetable abstract: Medical comorbidities and socio-economic inequalities are important risk factors for maternal death in the UK.