Pregnant women who take probiotics during pregnancy may lower their risk of pre-eclampsia and premature birth, a new study suggests.
Researchers examined expectant mothers' consumption of probiotics - live bacteria and yeasts which are usually added to yoghurts or taken as supplements.
The authors looked at data on more than 70,000 pregnancies in the Norwegian Mother and Child Cohort Study.
As part of the study, women provided information on diet, lifestyle and medical history at 15, 22 and 30 weeks of pregnancy.
Consuming probiotic products was more common among older, richer, better-educated mothers who were carrying their first baby.
The authors found that 23% of pregnant women had consumed probiotic milk products before their pregnancy; more than a third (37%) had done so in early pregnancy compared with 32% in late pregnancy.
They found that probiotic milk intake in late pregnancy - but not in pre-pregnancy or in early pregnancy - was significantly associated with lower pre-eclampsia risk.
And probiotic intake during early - but not before or during late pregnancy - was significantly associated with lower risk of pre-term birth.
The study is an observational one, so no firm conclusion can be drawn about cause and effect, but the researchers said that if future trials found a causal association between probiotics and the reduced risk of pre-eclampsia and pre-term delivery then "recommending probiotics would be a promising public health measure to reduce these adverse pregnancy outcomes".
Commenting on the research, Dr Patrick O'Brien, consultant obstetrician and spokesman for the Royal College of Obstetricians and Gynaecologists, said: "This is an interesting and large scale study with promising results showing that probiotic consumption during pregnancy, particularly in the early and late stages, lowers the risk of pre-eclampsia and premature birth.
"While these are positive findings, it is important to note the study demonstrates only an association and therefore no definitive conclusions can be made.
"More research is needed to determine these protective effects, and if proven, probiotic use could potentially be recommended as a public health measure to lower the pre-eclampsia and premature birth risk.
"Eating a healthy, well-balanced diet before, during and after pregnancy is crucial and will increase a woman's chances of conceiving
naturally and lower the risk of pregnancy and birth-related complications, including premature birth."