Early birth may cut serious complications and stillbirth risk in high blood pressure pregnancies without increasing caesarean rates, a Cochrane review suggests.

Planned early birth after 34 weeks cut serious maternal complications by nearly half compared with watchful waiting, the findings suggest.

It also likely reduced the risk of stillbirth by about 75 per cent, although the authors said this should be interpreted with caution.

Catherine Cluver, senior author of the review and researcher at Stellenbosch University and Tygerberg Hospital, said: “These findings give clinicians and women clearer guidance about the timing of birth when high blood pressure develops in pregnancy.

“For women with pre-eclampsia in particular, the evidence supports offering planned early birth from 34 weeks, and no later than 37 weeks.”

This Cochrane review, led by King’s College London, pooled data from six randomised controlled trials involving 3,491 women.

The trials compared planned early birth after 34 weeks with watchful waiting in women with one or more hypertensive disorders of pregnancy.

Hypertensive disorders of pregnancy, including pre-eclampsia, gestational hypertension and chronic hypertension, are the second leading cause of maternal death globally.

For women with pre-eclampsia, early birth remains the only definitive treatment, as the condition is driven by the placenta and will only resolve once it is delivered.

The trials took place in the Netherlands, UK, US, India and Zambia.

The review found high-certainty evidence that serious maternal complications were nearly halved in women who had planned early birth compared with those managed with watchful waiting.

The finding on stillbirth was based on moderate-certainty evidence and was driven by a single trial in India and Zambia, where stillbirth rates are higher. No stillbirths were recorded in the high-income country trials.

The review also found that planned early birth likely does not increase neonatal unit admission, although this finding was also based on moderate-certainty evidence.

The authors said the maternal benefit held across both high- and low-income settings, suggesting early birth reduces complications even when women are already receiving appropriate monitoring and care.

Alice Beardmore-Gray, lead author of the review and obstetrician at King’s College London, said: “Judging when to offer birth is the question that we battle with clinically every day.”

The authors added that in two of the trials, more than half the women allocated to watchful waiting ended up needing emergency birth before 37 weeks.

They typically gave birth just three to five days later than women allocated to planned early birth and often experienced more complications.

Beardmore-Gray said: “A common misconception is that by waiting longer, mum and baby are gaining more time, but often what you are doing is just delaying an inevitable emergency birth, when both may be in a worse condition.”

The review found high-certainty evidence of no increased risk of caesarean section associated with planned early birth.

Beardmore-Gray said: “That is the first question anyone asks when you offer them an early induction: won’t it increase my risk of a C-section?

“Being able to clearly answer no is a really important piece of information to give women when counselling them about the timing of their birth.”

The authors said the timing of birth should take into account the woman’s preferences and the severity of her condition.

They said these findings are consistent with and reinforce current international guidelines, which recommend that all women with pre-eclampsia should be offered planned early birth no later than 37 weeks.

Women with gestational hypertension or chronic hypertension without severe features may choose to continue with careful monitoring, with planned early birth considered from 39 weeks onwards.

Further research is needed on longer-term outcomes for infants born late preterm and on the long-term cardiovascular health of mothers affected by hypertensive disorders of pregnancy.