Pregnant women in Africa can reduce their risk of miscarriage or still birth by up to a third by sleeping under insecticide-treated bed nets.
Malaria, which mosquitoes pass on, kills a million people every year
The UK scientific research is likely to bolster calls for treated mosquito nets to be made more widely available to pregnant women and children in Africa.
Malaria is a preventable disease that kills more than 1m people a year, 90% of them in Africa - mostly children.
A treated net costs about $4 - simply too much for many African families.
This latest study drew on the results of four earlier trials in Kenya and Ghana involving more than 6,000 women.
The use of mosquito nets, treated with insecticide, it suggests, makes a big difference to the health of pregnant women and their newborn babies.
When they were used, the number of miscarriages and still-births fell by almost a third.
The number of babies born with a low weight also fell - by about a quarter.
Parasites that cause malaria are carried from human to human by mosquito
Kills more than a million people a year
90% of malaria deaths are in Africa
Malaria is Africa's leading cause of death for children under five
Earlier studies have focussed on the health impact on young children - but this is thought to be one of the first to show evidence of the impact on pregnant women.
A senior author of the report, Feiko Ter Kuile, of the Liverpool School of Tropical Medicine says the scale of these studies was crucial.
"We know that malaria itself is detrimental to many women who are pregnant and results in severe maternal anaemia and reduced birth weight in children," she said.
"But we simply didn't have the definitive answers because a lot of the clinical trials themselves were not large enough to be able to answer this question."
Global programmes to reduce malaria are trying to increase the use of nets - making them more available and more affordable.