Researchers Say Up to 25 Percent of Miscarriages Preventable

photo: Getty ImagesA miscarriage is one of the most traumatic events that can happen in a woman's life, and they're surprisingly common. But new research by scientists in Denmark suggests that it's possible that about a quarter of miscarriages could be prevented by lifestyle changes. 

About 50 percent of fertilized eggs spontaneously abort –– often before a woman is even aware she is pregnant –– usually because of chromosomal abnormalities but also because of exposure to toxic agents, maternal health disorders, illegal drug use, or other factors. In the United States, the miscarriage rate for women who know they are pregnant is between 15 and 20 percent. Researchers in Denmark wanted to determine the preventable risks of miscarriage and find out what percentage of miscarriages were caused by these factors. They published their findings in BJOG: International Journal of Obstetrics and Gynecology on Wednesday.

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The research team looked at data from approximately 90,000 pregnancies that occurred between 1996 and 2002 and were tracked by a national registry in Denmark. They focused on modifiable risk factors including exercise, alcohol consumption, smoking, drinking coffee, work schedule, regular heavy lifting, prepregnancy weight, and maternal age, and concluded that by lowering these risk factors, more than 25 percent of miscarriages could be prevented.

The prepregnancy factors they found that were most associated with lowering miscarriage risk were weight and age. Women who had a healthy body mass index (BMI) and were between 25 and 29 years old at the time of conception had a more than 14 percent lower risk of miscarriage. According to the data, the overall highest risk factors associated with miscarriage were drinking alcohol during pregnancy and a maternal age of 30 or over. Other factors that increased the chances of miscarriage involved a mother's job: lifting more than 40 pounds on a daily basis (by working as a caregiver or in a warehouse, for instance) and working at night.

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Over the last year, there has been some debate over the risk of moderate drinking during pregnancy triggered by studies on early pregnancy and alcohol consumption well as the controversial book "Expecting Better" by economist Emily Oster, which challenged the status quo on alcohol, sushi, and coffee among other pregnancy taboos. This new Danish study supports the continued stance of the American Congress of Obstetrics and Gynecology and the U.K. Royal College of Obstetricians and Gynaecologists that avoiding all alcohol is the safest approach for pregnant women.

Spotlighting maternal age is also sure to spark controversy, since birthrates for American women over 30 are at their highest levels since the 1960s (when women, on average, had more children). However, other studies confirm that the risk of miscarriage does increase with age. According to the American Pregnancy Association, women between the ages of 35 and 45 have a 20 to 35 percent of miscarriage and women over 45 have up to a 50 percent chance. "Everybody, young men and women, as well as those who have political responsibilities should bear in mind that postponing pregnancy to the mid-30s implies a seriously increased risk of miscarriage," Anne-Marie Nybo Andersen, senior researcher at the University of Copenhagen, said in a release. The researchers also acknowledged that while when you have a baby may be difficult to modify since it depends on so many complicated factors, they believe it is important to provide information about the "increased chances of having a successful pregnancy at a relatively young age."

Some critics of the study, however, are pointing out that risk is not the same as cause and urge a degree of caution when it comes to interpreting the results. According to an interview Patrick Wolfe, a professor of statistics at University College London, gave the Daily Mail, "The study does not establish a causal relationship between its reported risk factors and miscarriage." He added that it shouldn't be seen as "the last word" on an important and sensitive issue. "The main message from the paper," researcher Andersen clarified in a release, "is that miscarriages are a subject for prevention."

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