Postnatal depression linked to later heart, kidney and diabetes diagnoses in a study of 1.4 million women

When a woman leaves maternity care, the details of her pregnancy do not always follow her. “Pregnancy is often a woman’s first sustained contact with the health system, and complications during it can be an early sign of future health risks,” said Megha Singh, a research fellow at the University of Birmingham. “Yet once a woman is discharged from maternity care, that information is too often lost.”

Singh is one of the authors of a study, published on October 1 in BMJ Medicine, that tested how much that lost information might matter. Using the primary care records of 1,432,795 women in England who had been pregnant, the team found that a range of pregnancy complications went with higher rates of heart disease, type 2 diabetes, high blood pressure and chronic kidney disease in the years afterward. Some of those links have been known for a long time. The less familiar one was postnatal depression, which was associated with higher rates of all four conditions.

The study was led by researchers at the University of Birmingham and King’s College London as part of a national research consortium on pregnancy and long-term illness. The team is careful about what the numbers mean: they treat each complication as a clinical marker of underlying risk, a sign worth noting, and not as a cause of the disease that follows.

Which pregnancy complications the study tracked

Earlier research had already established that two families of complications raise later risk. Gestational diabetes is diabetes that first appears during pregnancy. Hypertensive disorders of pregnancy cover gestational hypertension, which is high blood pressure that starts in pregnancy, and pre-eclampsia, a pregnancy-specific disorder resulting in hypertension along with damage to other organs. For most other complications, the authors write, only limited evidence exists from systematic reviews.

So the team looked at ten. Alongside gestational hypertension, pre-eclampsia and gestational diabetes, they included miscarriage, stillbirth, placental abruption, preterm birth, babies born small or large for how far along the pregnancy was, and postnatal depression. In placental abruption, the placenta comes away from the inner wall of the womb before delivery.

Two other choices set the study apart. Most earlier studies had looked only at the most recent pregnancy and few examined chronic kidney disease. This one tracked complications in both the latest and any earlier pregnancy. It also added chronic kidney disease (stages 3-5), the more advanced grades, identified from a diagnosis code or from two blood tests at least 90 days apart showing the kidneys filtering well below normal.

How 1.4 million pregnancy records were followed

The records came from CPRD Aurum, a database of patient records from family doctors’ practices across England, linked to hospital data. It covers more than 12 million patients and reflects the national population in terms of geography, deprivation, and age. The team took women aged 15 to 49 who had been pregnant and were registered with a family doctor between 2000 and 2022.

Each woman’s follow-up began about six months after her latest pregnancy, to let the normal physical changes of pregnancy settle. It ran until she was diagnosed with one of the four conditions, moved practice, died or reached the end of 2022. Women who already had a condition were left out of the analysis for that condition. The average age at the start was 33.

Because women joined at different points over those 22 years, the median follow-up was only about four years. That is short for diseases that usually arrive in middle age, which is one reason the numbers diagnosed were small. Over that time, the most frequently diagnosed outcome was high blood pressure, in 49,233 women (3.5%), followed by type 2 diabetes in 21,754 (1.5%), heart disease or stroke in 16,069 (1.1%) and chronic kidney disease in 5,288 (0.4%).

The comparisons were adjusted for a long list of established risk factors, the kind a family doctor already has on file. They included age, ethnic group, deprivation, systolic blood pressure, body mass index, smoking status and alcohol misuse. Family history of heart disease and a range of existing illnesses and prescriptions were also counted. The question was whether a pregnancy complication told a doctor anything extra once all of that was known.

What the well-known pregnancy complications showed

For the familiar complications the answer was a clear yes. Women who had gestational hypertension or pre-eclampsia in the latest pregnancy were diagnosed with high blood pressure at roughly four times the rate of women without that history. For women who had it in an earlier pregnancy, the rate was two to three times as high. Gestational hypertension in the latest pregnancy also went with more than twice the rate of chronic kidney disease. Across the latest and earlier pregnancies, both blood pressure disorders were associated with increased rates for all four conditions, though the rises for heart disease and type 2 diabetes were smaller.

Gestational diabetes went with a sevenfold higher rate of type 2 diabetes, with higher rates of hypertension and heart disease as well, but it showed no clear link to kidney disease. The link held, at about sixfold, in women with a previous history of gestational diabetes from an earlier pregnancy.

Postnatal depression and the less familiar pregnancy links

Postnatal depression stood out among the less studied complications, for consistency more than size. For postnatal depression in the latest pregnancy, the rate of high blood pressure was 36% higher, type 2 diabetes 41% higher, heart disease and stroke 56% higher, and chronic kidney disease 35% higher than in women without that history. Depression after an earlier pregnancy carried similar, slightly smaller increases. The researchers count these consistent associations between postnatal depression and all four outcomes the first of their new results.

The other complications produced a patchier picture. Stillbirth in the latest pregnancy went with about two-thirds more type 2 diabetes and nearly 80% more chronic kidney disease. Placental abruption went with about two-thirds more kidney disease and somewhat more type 2 diabetes, links the team says have not been reported before. Preterm birth was tied to more heart disease. Babies born large for their stage of pregnancy were linked to higher rates of type 2 diabetes, even in women who had not had gestational diabetes. Babies born small were linked to more hypertension and, unexpectedly, somewhat less type 2 diabetes. Miscarriage showed only small links and none with diabetes. Some rarer complications thus had larger single links than postnatal depression did; what set depression apart was that it went with all four conditions. Most of the links held up after correction for multiple testing, which allows for the chance hits that come from running so many comparisons.

Francesca Crowe, a lecturer in epidemiology at Birmingham and another of the authors, said the size of the records was what made the broader view possible. “Using large-scale primary care records, we could look at a wide range of pregnancy complications together rather than only focussing on one at a time,” Crowe said. “We now need to understand why these links exist and whether earlier support after pregnancy can change outcomes for women.”

The authors suggest possible routes for these links, while stressing that how pregnancy complications raise later risk is not fully understood. Postnatal depression often involves chronic inflammation and disruption of the body’s stress-hormone system, they write, which can raise cortisol and make the body less responsive to insulin, and depression can also bring changes in diet and activity. For complications such as pre-eclampsia, abruption and stillbirth, they point to shared problems with blood vessels; for large babies and gestational diabetes, to shared problems with how the body handles sugar.

How the results fit earlier research on pregnancy and heart disease

The established links point the same way as larger bodies of evidence. A 2020 meta-analysis in the BMJ pooled 20 studies with more than 1.3 million women. Those with previous gestational diabetes had an almost 10 times higher rate of type 2 diabetes than women whose blood sugar had stayed normal in pregnancy. A 2017 review of 22 studies covering more than 6.4 million women found that pre-eclampsia was associated with a 4-fold increase in future heart failure and roughly double the risk of coronary heart disease, stroke and death from heart disease.

The depression finding has independent support too. A Swedish nationwide study published in 2024 followed 55,539 women diagnosed with depression during or after pregnancy, and 545,567 unaffected women matched to them, for up to 20 years. Over that time, 6.4% of the women with perinatal depression developed heart or blood vessel disease, against 3.7% of the comparison group, and the women with depression had a 36% higher risk after adjustment. When the researchers compared affected women with their own sisters, who share much of the same family background, the increase shrank to a 20% higher risk but did not disappear.

The American Heart Association reached a similar view of the wider field in a 2021 scientific statement. It said adverse pregnancy outcomes increase a woman’s risk of heart disease and its risk factors and should be recognized when heart risk is evaluated, although their value in reclassifying risk may not be established. Postnatal depression was not among the outcomes it listed.

Why these pregnancy complications are warning signs, not causes

A marker, by design. The authors chose their adjustments to answer a prediction question, whether a complication adds information beyond the usual risk factors, and say plainly that their figures do not estimate the effect of the complication itself. Several complications share roots and often occur together, so the separate figures should not be viewed as additive, they add.

Short follow-up. With a median of about four years, the study describes the years soon after pregnancy. Longer term follow-up will be important, the researchers say, to see whether the picture changes later in life.

Closer watching. Women who had a complication saw doctors more often and had blood pressure and blood sugar measured more often. Some of the extra diagnoses may reflect conditions found earlier rather than conditions that were more common, and the authors write that differential detection could contribute to the results. They also point out that women in whom hypertension or diabetes is developing would visit more often anyway in the months before a diagnosis.

Missing pieces. Diet and physical activity are not well recorded in family doctors’ notes, ethnicity was missing for around a fifth of the women, and early miscarriages that never reached a doctor were probably undercounted. Pregnancy-related acute kidney injury, a known risk factor for later kidney disease, could not be captured.

Who paid. The work was publicly funded, through a UK research program on multiple long-term illnesses run by the National Institute for Health and Care Research and the Medical Research Council. The researchers report no financial ties to organizations with an interest in the results.

What a pregnancy history adds to heart and kidney risk

The authors argue that a full reproductive history, including complications from earlier pregnancies, belongs in routine risk assessment, and they note that postnatal depression and placental abruption are not currently included in the risk calculators commonly used in UK practice. A 2021 review in JAMA Cardiology found that cardiovascular guidelines endorse using a history of adverse pregnancy outcomes to refine heart risk assessment, while awareness of the link remains low among both patients and clinicians. Whether recording a pregnancy history changes any one woman’s care is assessed by her doctor.

The study widens the list of pregnancy events that may be worth having on record, without showing that any of them causes the diseases that sometimes follow.