A large UK study published in The Lancet Public Health has found that women who enter pregnancy with two or more long‑term physical or mental health conditions face substantially greater risks of a wide range of pregnancy complications. The analysis of anonymised records from more than 2.2 million pregnancies also highlights how maternity services organised around single conditions may fail to identify or manage combined risks.
Key findings and what they mean for care
Researchers co‑led by the University of Birmingham compared women with multiple long‑term conditions — such as asthma, diabetes, hypertension, depression or anxiety — present before conception to those with none. They report that the presence of two or more pre‑existing conditions was associated with increased likelihood of:
- severe pregnancy sickness (hyperemesis gravidarum),
- gestational diabetes,
- raised blood pressure and pre‑eclampsia,
- liver conditions,
- placental abruption,
- blood clots (venous thromboembolism),
- miscarriage, and
- higher rates of anxiety and depression during pregnancy.
Importantly, the study found a dose–response pattern: the risk of complications rose with each additional long‑term condition. The authors stress that the combined effect of multiple conditions is not well captured by current models of maternity care, which are typically organised around single conditions and delivered by separate teams.
"Around one in five pregnant women in the UK currently live with two or more long‑term health conditions," said Megha Singh, Research Fellow at the University of Birmingham.
Implications for NHS maternity services
The analysis reinforces calls for more integrated, multidisciplinary approaches to maternal health from the first antenatal appointment. When care is fragmented across specialties, clinicians may not routinely monitor cumulative risk attributable to coexisting conditions. That gap can delay recognition of complications and complicate decision‑making about surveillance, medication and delivery planning.
From a policy perspective, the findings suggest that risk assessment tools and commissioning pathways should explicitly account for multimorbidity in reproductive‑age women. Evidence‑led changes could include shared care plans, co‑ordinated obstetric, medical and mental health input, and targeted postpartum follow‑up given the higher risk of perinatal mental illness identified.
Strengths and limits of the evidence
The study’s principal strength is its size — more than 2.2 million pregnancy records — and the use of routinely collected data that enhance generalisability across UK maternity services. However, as with all observational record‑linkage studies, the analysis can identify associations but cannot on its own prove causation. Residual confounding is possible if some risk factors were not fully recorded in the datasets.
Additionally, the study grouped a wide range of physical and mental conditions. The absolute risk increase for any single woman will depend on the specific combination and severity of conditions, sociodemographic factors and access to care. The authors therefore call for research to refine prediction models and to evaluate integrated care pathways in prospective studies.
Next steps for clinicians and commissioners
Clinicians should be alert to multimorbidity in pregnancy and consider early multidisciplinary involvement. Commissioners and service planners will need to consider:
- revising antenatal risk assessment to include cumulative multimorbidity;
- facilitating joint clinics or care coordination between obstetrics, primary care, medical specialties and mental health services; and
- evaluating targeted interventions to reduce specific complications in women with multimorbidity.
The study adds to a growing body of evidence that maternal health policy must move beyond single‑condition silos if the NHS is to reduce preventable pregnancy harm. Strengthening data collection and trialling integrated service models will be key to translating these findings into safer care for mothers and babies.
