Bending forwards at work may be an overlooked risk for pregnant women

Pregnant women who frequently bend forward at work could face an increased risk of miscarriage, according to a new study from the University of Copenhagen. The researchers believe that greater attention should be paid to the working environment in early pregnancy.
Waiter, farm worker, gardener, and craftsperson are occupations where women have to do the most forward-bent work. Photo: Getty Images/Liderina

Up to 20% of pregnancies end in miscarriage. That’s why it is important to understand whether some risk factors can be prevented. A new study from the University of Copenhagen and Bispebjerg Hospital suggests that an overlooked factor may increase the risk of pregnancy loss: working in a bent-forward position.

The researchers analysed data from 800,000 pregnancies and found that for every hour women spent working bent forward, the risk of miscarriage increased by 36%. In addition, each hour of walking or standing work was associated with an increased risk of pregnancy loss of 18% and 3%, respectively.

"Losing a pregnancy is devastating for a woman, so if there is anything we can do to help prevent it, it is important that workplaces are aware of how the risk may be reduced," says Luise Mølenberg Begtrup, Clinical Associate Professor at the Department of Public Health, University of Copenhagen.

Gardeners and waiters often work bent forward

In the study, the researchers analysed more than 800,000 pregnancies among 475,000 women between 2004 and 2018 and linked these data with measurements of occupational postures.

More than 400 women wore sensors on their backs and thighs while working. The sensors recorded how much they walked, stood and bent forward during a typical working week across 100 different occupations.

Occupations involving frequent forward bending included waiters, agricultural workers, gardeners and tradespeople. Prolonged standing was particularly common among jobs such as bakers, shop assistants and painters, while occupations involving a high degree of walking included waiters, chefs, food production workers and refuse collectors.

"When people are asked how many hours they spent walking during a working day, for example, they often find it difficult to remember accurately and tend to overestimate. With this method, we avoid relying on self-assessments, which reduces uncertainty," says Hannah Nørtoft Frankel, physician at Bispebjerg Hospital and lead author of the study, which was part of her PhD project at the University of Copenhagen.

The study found that forward-bending work in particular increased the relative risk of miscarriage. The risk increased by 36% for each additional hour spent working bent forward.

"That is quite a high figure. On the other hand, it is relatively rare for people to spend more than an hour in total bent forward during a working day. In fact, the average worker spent only 24 minutes a day in a bent-forward position," says Luise Mølenberg Begtrup.

Unclear why

In the study, the overall risk of miscarriage among participants was 10%, somewhat lower than the risk in the general population. However, for women who spent one hour working bent forward, the risk of miscarriage was 13.6%, corresponding to a 36% increase compared with the overall risk.

Miscarriages

  • A miscarriage occurs when a pregnancy ends before 22 weeks of gestation.
  • The vast majority of miscarriages occur within the first 12 weeks of pregnancy.
  • It is estimated that up to 20% of all pregnancies end in miscarriage. In Denmark, this corresponds to around 20,000 miscarriages each year.

  • Sources: Sundhed.dk, Rigshospitalet

The researchers do not yet know why working bent forward appears to be particularly risky during pregnancy.

"The underlying mechanism remains poorly understood. One possible explanation is that bending forward may restrict blood flow to the placenta. It could also be that it triggers stress hormones that induce contractions in the uterus, which could potentially lead to miscarriage," says Hannah Nørtoft Frankel.

The researchers emphasise that the study does not show that physical work directly causes miscarriage. Most miscarriages result from factors beyond the control of either the pregnant woman or her workplace, and the findings point only to a statistical association that requires further investigation.

Employers should be aware

The researchers stress that pregnant women should not be worried about going to work, even if their job involves walking, standing or bending forward.

"In general, it is healthy to remain active and continue working during an uncomplicated pregnancy. However, there are occupations where employers should pay attention to whether a pregnant employee spends much of the working day standing, walking or bending forward. In such cases, employers should consider how tasks can be adjusted and work adapted accordingly," says Luise Mølenberg Begtrup.

Often, relatively small adjustments can make a difference, such as taking more seated breaks during the day or providing a chair instead of requiring employees to stand. It may also be possible to swap tasks with a colleague for a period.

Employers are required to discuss working conditions with pregnant employees to assess and adapt the working environment where necessary. However, current recommendations from the Danish Working Environment Authority concerning standing and walking work apply only from the fourth month of pregnancy onwards in Denmark. The researchers believe this is too late, since most miscarriages occur earlier in pregnancy.

"We believe these recommendations should apply throughout pregnancy," says Hannah Nørtoft Frankel.

The researchers hope that the findings will help both pregnant women and employers assess working postures throughout pregnancy.

"If someone feels they are exposed to particularly demanding working conditions and is unsure whether these could pose a risk to their pregnancy, they can always be referred for an individual risk assessment and guidance at an occupational medicine department," says Luise Mølenberg Begtrup.

About the study

  • 803,829 pregnancies among 475,312 women were analysed.
  • The study used data from 2004 to 2018.
  • 10.1% of pregnancies ended in miscarriage.
  • The researchers examined occupational standing, walking and forward bending, defined as bending more than 30 degrees.
  • 400 women wore accelerometers while working to record their movements.
  • For occupations with insufficient measurement data, the researchers supplemented their analyses with expert assessments of working postures.
  • Each hour of forward-bending work was associated with a 36% increase in the relative risk of miscarriage, while each hour of walking and standing work increased the risk by 18% and 3%, respectively.
  • The researchers cannot determine whether the increase in pregnancy loss is directly caused by work. Other factors, such as smoking and the pregnant woman's overall health, may also play a role.
  • The study was published in the journal Occupational and Environmental Medicine.

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