Bending forwards at work during early pregnancy may increase the risk of miscarriage, according to a large study of more than 470,000 Danish women published online in the journal Occupational & Environmental Medicine on June 18. The research found that each additional hour spent bending forwards, particularly at a 30-degree angle, was associated with a 36% higher risk of miscarriage. Each additional hour of walking was linked to an 18% higher risk, although this pattern was only consistent for forward bending.
Miscarriage affects around 15% of women, and known risk factors include parental age, smoking, night shift work, and exposure to air pollution and certain chemicals. Previous evidence has suggested that workplace standing, walking, and forward bending may also raise the risk but findings have been inconclusive. With nearly 70% of women in Europe participating in the workforce, concerns remain about safe levels of occupational physical activity during pregnancy.
Researchers analyzed data from a national register covering pregnancies among working women living in Denmark between 1977 and 2018. They focused on over 475,000 women with more than 800,000 pregnancies from January 2004 to December 2018. An improved job exposure model combining activity tracker readings and expert evaluations estimated time spent standing, walking, or forward bending at a significant angle.
The study reported that just over one in ten pregnancies (81,307) ended in miscarriage—a figure lower than usual prevalence rates—possibly because many early miscarriages are managed outside hospitals and thus not registered. Analysis showed that standing, walking, and especially forward bending were all associated with increased risks of miscarriage: each extra hour per day spent forward bending raised the risk by about one third; each extra hour walking or standing increased it by smaller amounts.
The researchers noted a stronger association among women who had been absent from work the previous week compared to those who had not. Only forward bending showed a consistent dose–response relationship across analyses.
As an observational study without individual-level data on factors such as smoking or lifting during pregnancy—and lacking information on shift work or chemical exposures—the authors caution against drawing firm conclusions about causality. "Although the mechanisms are not completely understood, these occupational exposures may affect placental perfusion or hormonal regulation in ways that could increase the risk of miscarriage," they said. The researchers highlighted that there are currently no formal guidelines addressing occupational standing or walking within the first four months of pregnancy nor guidance regarding forward bending for pregnant workers in Denmark.
