Air pollution from cooking indoors over a fire of wood or charcoal could have life-threatening consequences for some pregnant women, according to a new study.

Researchers at King’s College London found “a significantly positive correlation” between deaths attributable to toxic smoke from cooking and heating and the rate of eclampsia, a rare condition in pregnancy where high blood pressure results in life-threatening seizures. Women with pre-eclampsia, characterised by high blood pressure or hypertension, are at significantly greater risk in pregnancy if they are cooking over an open fire.

Solid-fuel fires inside homes, commonplace in low and middle-income countries, also exacerbate the risk of placental hypoxia, when the foetus’s oxygen supply is affected, according to the study, published in the International Journal of Gynecology & Obstetrics.

Prof Andrew Shennan, a lead author of the study, said the research “could help explain observed inequalities in maternal healthcare in low and middle-income countries”.

Researchers looked at eight countries: Ethiopia, Haiti, India, Malawi, Sierra Leone, Uganda, Zambia and Zimbabwe. Overall, 2,692 cases of eclampsia in 536,223 deliveries were studied in the trial.

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“In-house cooking and household pollution may increase the risk of seizures. We believe that less oxygen will get to the mother’s brain, and this may trigger a fit in women who already have pre-eclampsia,” said Shennan.

“We are lucky to have such a large dataset of women with eclampsia, as it only occurs in 1% of women with pre-eclampsia. This has allowed us to uncover this new finding.

“This could help explain observed inequalities in maternal healthcare in low and middle-income countries,” he said.

“We have large programmes of work in India, Sierra Leone and Zambia, where many women have complications related to high blood pressure. Our current research is aimed at identifying the women at risk but now we are looking at ways to reduce risk, including earlier delivery. This data will help us to give advice about avoiding risk at home.”

A previous study conducted by King’s College London researchers showed that 94% of maternal deaths occur in low and middle-income countries, with 22% due to high blood pressure disorders such as eclampsia.