One in four miscarriages might be preventable, researchers have said.
Paying closer attention to avoidable risks, such as being underweight or obese before conception and drinking alcohol in pregnancy, could help reduce the toll, a study claims.
Working nights and lifting heavy loads also increased the chance of miscarriage, as did being aged over 30, the Danish team said.
They claimed that if women were able to cut these risk factors to very low levels, 25 per cent of miscarriages could be prevented.
However, other scientists warned the study did not show that these factors cause miscarriages.
Each year, a quarter of a million British women have a miscarriage. Most happen in the first 12 weeks of pregnancy, but up to 10,000 occur at a later stage.
Scientists from the University of Copenhagen, Denmark, looked at 91,427 pregnancies between 1996 and 2002, of which 3,177 ended in miscarriage before 22 weeks.
At 16 weeks, women were asked about their lifestyle before conception and during pregnancy. Those who had already had a miscarriage were asked about their habits before it took place. The study found age, drinking alcohol, lifting more than 44lb (20kg), night shifts and being obese or overweight were all associated with miscarriage.
Age and alcohol were the most significant factors, the report in BJOG: An International Journal of Obstetrics and Gynaecology said.
It added: ‘In a prevention scenario where women conceived at the age of 25 to 29 years, consumed no alcohol during pregnancy, were normal weight before pregnancy, did not lift more than 20kg daily during pregnancy, and worked only during the day, 25.2 per cent of miscarriages were preventable.
‘This scenario resulted in the highest preventable proportion of miscarriage.’
Sandra Feodor Nilsson, one of the researchers, said: ‘Miscarriage is the most common adverse pregnancy outcome, affecting at least one in seven pregnancies.’
Half of all miscarriages result from chance abnormalities in the baby’s chromosomes, which can cause the mother’s body to reject the fetus.
Professor Tom Bourne, a consultant gynaecologist at London’s Queen Charlotte’s and Chelsea Hospital, said: ‘This is a big study, but it does not really say anything new. There are also issues of recall bias, and the fact that they show an association rather than causation.
‘Saying that by changing x or y a percentage of miscarriages could be prevented is quite a statement in the absence of an interventional trial. However, it adds to the view that alcohol in pregnancy is not a good idea.’
Patrick Wolfe, a professor of statistics at University College London, said: ‘This study does not establish a causal relationship between its reported risk factors and miscarriage.
‘The study has several statistical limitations, and so I caution that its conclusions may be subject to over-interpretation.’ He said it should not be seen as ‘the last word’ on the issue.