Women who begin pregnancy with two or more pre-existing, long-term physical or mental health conditions have 20% higher risk of miscarriage, 69% higher risk of severe nausea and vomiting, and around four times the risk of anxiety and depression, compared with those with no long-term conditions.
The new research, co-led by King's College London, also found those with multiple long-term conditions had more than double the risk of venous thromboembolism (where a blood clot forms inside a vein, such as in deep vein thrombosis and pulmonary embolism), and 42% higher risk of pre-eclampsia (a pregnancy complication that causes high blood pressure) compared to those without long-term conditions. Risks rose with each additional condition. For women with three or more conditions, the risk of venous thromboembolism was more than three-and-a-half times that of women with no long-term health conditions.
The new study, published today in The Lancet Public Health , compared antenatal outcomes in women with and without multiple long-term conditions. The study, led by researchers at King's College London, Queen's University Belfast, Bristol NHS Foundation Trust, the University of Birmingham, Swansea University and the University of St Andrews, is the largest of its kind – analysing data from pregnancies across all four UK nations.
Around one in five pregnant women in the UK live with multiple long-term conditions, yet the combined impact of these conditions on pregnancy is poorly understood. In an observational study, researchers from the MuM-PreDiCT consortium analysed over 2.2 million pregnancies and birth events recorded between 2000 and 2022 in five datasets spanning England, Scotland, Wales and Northern Ireland.
Compared to women with no long-term conditions, women with multiple long-term conditions also had a 32% higher risk of placental abruption, where the placenta separates from the womb before birth, and a 26% higher risk of gestational diabetes.
Dr Steven Wambua, Research Fellow in Health Data Science at King's College London and joint first author, said: "Maternity care is still largely organised around single health conditions, but one in five women now enters pregnancy with two or more. By harmonising five datasets covering all four UK nations, we could show consistently and across a much broader range of outcomes than before, that these women face higher risks and that risk climbs with every additional condition."
Maternity care pathways vary considerably, but where they exist, they are often organised around individual conditions. The authors say their findings highlight a need to restructure these pathways to address the complex needs of women living with multiple conditions.
Ngawai Moss, who has lived experience of pregnancy with long-term health conditions and is a Patient and Public Involvement co-investigator on MuM-PreDiCT, said: "I shouldn't have to join all the dots myself. I don't always know what I need, what questions to ask or who I need to speak to. Every pregnancy is different, and I need my care to work around me, not the other way around."
Professor Krishnarajah Nirantharakumar, Clinical Professor of Public Health and Health Data Science at King's College London, MuM-PreDiCT principal investigator and joint senior author, said: "These findings make a strong case for recognising multiple long-term conditions as a marker of antenatal risk in its own right. That means identifying these women at maternity booking, assessing physical and mental health needs together, and joining up obstetric, primary care and mental health services around them. The near four-fold risk of antenatal anxiety and depression is particularly striking, and points to perinatal mental health support as an urgent priority."
Dr Kelly-Ann Eastwood of Bristol NHS Foundation Trust and Queen's University Belfast, joint senior author, said: "Our results help define the urgent clinical challenges facing both women entering pregnancy with multiple long-term conditions, and clinicians caring for them across the UK. Supporting recommendations from recent national maternity and neonatal investigation reports, there is a critical need to address healthcare inequalities, and improve support for women with pre-existing mental health conditions. These findings highlight the pressing need to restructure existing maternity services to improve antenatal outcomes."
The authors note that, as an observational study using routinely collected health records, some conditions and outcomes may be under-recorded or inconsistently recorded.
The study is funded by the UKRI Strategic Priorities Fund and the Department of Health and Social Care via the National Institute for Health and Care Research (NIHR), and delivered by the Medical Research Council (MRC).
The MuM-PReDiCT consortium was established with the aim of improving care for pregnant women with multiple long-term health conditions. Further work within MuM-PreDiCT will examine birth and child outcomes and identify which combinations of conditions carry the greatest risk.
