A quarter of miscarriages may be preventable, research suggests.
Being underweight or obese before conception, working nights, drinking alcohol in pregnancy and lifting heavy loads could all increase the risk, experts said.
They said if women cut these risks to very low levels, 25 per cent of miscarriages could be prevented. The large study of more than 91,000 pregnancies also confirmed that one of the biggest factors influencing miscarriage is the mother’s age, with women over 30 having a higher risk.
However, other researchers cast doubt on the study by a team from the University of Copenhagen in Denmark, which used data from 91,427 Danish pregnancies between 1996 and 2002.
They regarded miscarriage as a baby lost before 22 weeks of pregnancy and found that 3,177 of the total sample resulted in miscarriage. In telephone interviews women were asked about their habits leading up to conception and during pregnancy.
The study found that age, drinking alcohol, lifting more than 20kg a day, night shifts and being obese or overweight all contributed to miscarriage. A mother’s age and alcohol consumption were the most important risk factors.
The researchers estimated that 11.4 per cent of miscarriages could be prevented if women conceived aged 25 to 29, and nine per cent of miscarriages could be prevented if no alcohol was consumed.
According to the NHS Choices website for patients, one in seven pregnancies in the UK end in miscarriage and most are due to chromosomal abnormalities.
If a miscarriage happens during the second trimester of pregnancy (between weeks 14 and 26), it says an underlying health condition in the mother may be to blame.
However, women can reduce their risk by avoiding smoking, drinking or using drugs and keeping to a healthy weight.
Professor Tom Bourne, a consultant gynaecologist at Queen Charlotte’s and Chelsea Hospital in London, said: “This is a big study, but it does not really say anything new.”
Patrick Wolfe, professor of statistics at University College London (UCL), cast doubt on the methodology and pointed out: “This study does not establish a causal relationship between its reported risk factors and miscarriage.”