High Blood Pressure in Pregnancy: What It Means for Babies Born Very Early, in Hospital and Beyond

Two studies — Yang and colleagues (2026) and Atkinson and colleagues (2025) — on the health problems these babies face together, and how they develop as they grow

High blood pressure in pregnancy, including pre-eclampsia, is a common reason babies are born very early. New research suggests these babies are more likely to grow slowly in hospital alongside a second problem such as liver strain, an underactive thyroid or lung disease, and that children exposed to high blood pressure before birth are somewhat more often diagnosed with developmental conditions. Much of that later link may come from being born early or small.

Why researchers wanted to know more

If your baby was born early because of your blood pressure, you may have wondered whether the illness itself affected them. It is a fair question, and until recently the honest answer was "we are not sure". Pre-eclampsia is a condition in which the placenta (the organ that feeds the baby in the womb) does not work properly. It releases substances that damage the mother's blood vessels and raise her blood pressure, it can slow the baby's growth, and the only cure is to deliver the baby [1]. That is why so many babies of mothers with pre-eclampsia are born early by planned delivery.

Doctors have known for some time that women who had pre-eclampsia face higher heart and blood-vessel risks later in life [2]. What it means for the child has been much less clear. Researchers who pooled earlier studies found slightly higher rates of autism and attention-deficit/hyperactivity disorder (ADHD, a condition affecting attention and self-control) in children whose mothers had high blood pressure [3]. But a large Swedish study that compared brothers and sisters within the same families found that the link with intellectual disability (sometimes called a learning disability) and with lower thinking-test scores mostly disappeared, suggesting that shared family factors, rather than the blood pressure itself, explained much of it [4].

The picture inside the newborn intensive care unit (NICU, the hospital ward for very small or sick babies) was just as confusing. A study pooling six national newborn-care networks found that babies born at 24 to 28 weeks after high blood pressure in pregnancy were, if anything, slightly less likely to die or to have serious brain injury, but slightly more likely to develop chronic lung disease [5]. At the same time, doctors were realising that very early babies rarely face just one problem: in one group of ten hospitals, only about a third of the tiniest survivors left hospital without any of eight major complications [6]. And having several complications together matters, because babies who had more of them were less likely to survive without serious developmental difficulties at age two [7]. Very little research had looked at whether a mother's high blood pressure changes which problems tend to come together [8].

The two studies and how they fit together

The first study, published in September 2025 by Atkinson and colleagues in Australia, looked at the long-term picture [9]. Rather than following children themselves, they gathered 121 earlier studies from 31 countries, covering almost 30 million children, of whom about 1.1 million had been exposed to high blood pressure before birth. This kind of study, called a meta-analysis, combines many results to see the overall pattern.

The second study, published in July 2026 by Yang and colleagues, zoomed in on the hospital stay [8]. It followed 7261 babies born between 24 and 31 weeks of pregnancy and cared for in 47 NICUs in China between 2019 and 2023, as part of a large research project called the CARE-Preterm (Chinese Adverse Prognosis of Very Preterm Infants) cohort, which draws on hospitals across northern China [10]. About one in four of these babies (1919) had a mother with high blood pressure. The researchers compared these babies with the others, followed them until they went home, and looked at which problems tended to occur together in the same baby. The two research teams did not refer to each other's work; In[Neo]Sight has brought them together because they cover two halves of the same journey.

What the hospital study found

The biggest difference was in growth. Doctors use a term, extrauterine growth restriction, for a baby who is still below the 10th centile for weight (lighter than 90 out of 100 babies of the same age) by the time they go home or reach 36 weeks, measured on a standard chart [11]. About 47 in every 100 babies of mothers with high blood pressure were in this group, compared with about 25 in every 100 other babies [8]. An underactive thyroid (the gland in the neck that controls growth and energy) affected about 10 in 100 versus 6 in 100, and liver strain linked to long-term intravenous feeding affected about 12 in 100 versus 8 in 100. Babies of mothers with high blood pressure also took a few days longer to reach full milk feeds.

When the researchers looked at combinations, the four most common ones all involved slow growth plus one other problem: liver strain, an underactive thyroid, chronic lung disease, or a serious eye condition of prematurity called retinopathy. Even after allowing for the fact that these babies were often smaller and had different birth circumstances, each combination was roughly twice as likely when the mother had high blood pressure [8]. Reassuringly, there was no clear difference in serious brain bleeding or a severe bowel illness, and there was no clear difference in the chance of dying in hospital (about 3 in 100 versus 2 in 100, which was not a reliable difference). The researchers suggest that these babies may start life a little more vulnerable, and that the treatments they need in hospital then act as a "second hit" — an idea other experts have also put forward [12].

What the childhood study found

Atkinson's review found that children exposed to high blood pressure before birth were more often diagnosed with autism, ADHD, intellectual disability and general developmental delay, and on average scored about 2 points lower on IQ tests, a small difference [9]. There was no clear link with cerebral palsy. The increases were modest: for ADHD, for example, the odds were about one quarter higher.

The most important part of the review is what happened when the researchers looked only at studies that took into account how early or how small babies were at birth. In those studies, several of the links became weaker or disappeared. That suggests much of the extra risk may come from being born early or small, rather than from the blood pressure itself — a finding echoed by an Australian study of school results [13]. Among babies born very early, the evidence is mixed: one Canadian study found more developmental difficulties after maternal high blood pressure, especially if the baby was also small [14], while an American study across nine hospitals found that poor growth in the womb, not pre-eclampsia, was what mattered at age two [15].

What this means for your family

If your baby was born early because of high blood pressure, these studies do not mean something will go wrong. They describe groups of babies, not any one child, and they show links rather than proof of cause. What they do suggest is that it makes sense for your baby's team to watch growth closely, check liver tests if intravenous feeding goes on for a long time, and check thyroid function more than once. The Chinese researchers recommend weekly thyroid blood tests for the first four weeks of life, because in very early babies thyroid problems often show up only on later tests rather than the first one [8][16].

You can ask the team questions such as: How is my baby's growth tracking? Are thyroid tests being repeated? Will we be offered developmental follow-up after discharge? If you want to read about preventing pre-eclampsia in a future pregnancy, our article on aspirin and pre-eclampsia may help.

Some honest limits

Both studies have limits. The hospital study took place in one country, could not separate different types of high blood pressure, and stopped when babies went home, so it tells us nothing directly about later development. It also left out 855 babies whose intensive care was withdrawn, which the researchers recognise may have removed some of the most vulnerable babies from the comparison. The childhood review combined studies that varied a great deal, and few of them took into account the baby's size and gestation at birth or the family's own circumstances.

What researchers are working on next

The natural next step is to follow babies like those in the Chinese study into childhood, to see whether the combinations of problems in hospital predict later development, and whether extra support helps. Researchers also want to study each type of high blood pressure separately, and to combine the original data from many studies so that the effect of being born early or small can be untangled properly.

In summary

Babies born very early after high blood pressure in pregnancy are more likely to grow slowly in hospital alongside a second problem, and children exposed to high blood pressure before birth are somewhat more likely to receive developmental diagnoses — partly because of being born early or small. Careful monitoring of growth, liver and thyroid in hospital, and developmental check-ups afterwards, are sensible ways to make sure any difficulties are spotted and supported early.

References

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  2. Wu P, Haththotuwa R, Kwok CS, et al. Preeclampsia and Future Cardiovascular Health: A Systematic Review and Meta-Analysis. Circ Cardiovasc Qual Outcomes. 2017;10(2):e003497. doi:10.1161/CIRCOUTCOMES.116.003497 ↩
  3. Maher GM, O'Keeffe GW, Kearney PM, et al. Association of Hypertensive Disorders of Pregnancy With Risk of Neurodevelopmental Disorders in Offspring: A Systematic Review and Meta-analysis. JAMA Psychiatry. 2018;75(8):809-819. doi:10.1001/jamapsychiatry.2018.0854 ↩
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  9. Atkinson JA, Gordon HG, Tong S, et al. Hypertensive disorders of pregnancy and childhood neurodevelopment: A systematic review and meta-analysis. PLoS Med. 2025;22(9):e1004558. doi:10.1371/journal.pmed.1004558 ↩
  10. Shi R, Dong X, Wang L, Zhang W, Reddy S, Yu Y. The Chinese adverse prognosis of very preterm infants (CARE-Preterm) cohort: study design and baseline characteristics for a prospective multicenter cohort study. BMC Pediatr. 2025;25(1):377. doi:10.1186/s12887-025-05722-5 ↩
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