June 18, 2026

expert reaction to study looking at bending, standing and walking while at work during pregnancy, and risk of miscarriage

A study published in Occupational & Environmental Medicine looks at bending over during pregnancy and the risk of miscarriage. 

Prof Asma Khalil, Professor of Obstetrics and Maternal Medicine and Consultant Obstetrician, City St George’s, University of London, said:

“This is a large, well-conducted nationwide register-based cohort study using Danish data from more than 800,000 pregnancies.  A key strength is the use of a pregnancy-specific job exposure matrix to estimate occupational standing, walking and forward bending, which reduces recall bias compared with self-reported exposure.

“The main finding is that forward bending at work was associated with an increased risk of miscarriage, with a more consistent dose-response pattern than was seen for standing or walking.  However, this is an observational study, so it cannot prove causation.  Important limitations include the lack of individual-level data on smoking for most miscarriages, inability to adjust for lifting, and potential confounding from other occupational exposures such as shift work or chemical exposures.

“The press release is broadly accurate and appropriately notes that firm conclusions about cause and effect cannot be drawn.  However, the findings should not be interpreted as meaning that ordinary movement in early pregnancy is unsafe.  The study relates to occupational patterns of exposure, particularly prolonged or repeated forward bending, rather than everyday activity.

“While the study raises an interesting hypothesis regarding occupational postures and miscarriage risk, the findings need replication and confirmation in other populations before they can be translated into precise workplace guidance.”

Prof Andrew Shennan OBE, Professor of Obstetrics, King’s College London, said:

“This large study has linked certain behaviours at work, particularly bending and standing to miscarriages.  The reported size of effect is very small.  This is a large dataset and the analysis is well performed.  However the findings should be interpreted with caution.  Like all retrospective studies it is difficult to test causation i.e. is the behaviour the actual cause of the miscarriage; for example there maybe other reasons for the findings.  For example, those in more physical jobs maybe are more likely to report a miscarriage as a reason to be off work.  Reassuringly prospective studies have not found such associations.  In addition, it is difficult to link a likely mechanism as many miscarriages are due to clear genetic reasons and these activities very unlikely to influence placental physiology or hormonal profiles as suggested.  As with all good research this has highlighted an important area to consider further but should not change current policy.”

Prof Kevin McConway, Emeritus Professor of Applied Statistics, Open University, said:

“I’m starting by pointing out one piece of information that’s not mentioned in the press release, and indeed isn’t very obvious in the research paper.  But it matters in interpreting the findings.

“The release says, for instance, “Each additional hour of bending forwards, particularly at a 30 degree angle, was associated with a 36% higher risk [of miscarriage]”.  Similar wording is used about walking and standing time.

“You might wonder about what this means – an additional hour compared to what?  It doesn’t mean an additional hour of bending forward, at work, on one occasion during pregnancy.  That makes no sense, if you think about it.  Just one hour, throughout pregnancy can’t be associated with an increase in the risk of a miscarriage by as much as 36%, can it?

“That’s not what it means, though.  It means an additional hour of bending forward, throughout the first few months of pregnancy on average, during each 8-hour working day.  That is a lot more plausible, I’d say.  An increase in bending time of, on average, one hour in every eight hours of work is quite a substantial increase in time spent bending forward.  So it’s not out of the question that it might be associated with a substantial increase in miscarriage risk.

“I don’t really blame the writers of the press release for not including the information about 8 hours.  The Abstract of the paper, and its Results section, also do not mention it.  (It appears only on one sentence in the Methods section of the paper, and in a footnote to Table 1.)

“In any case, we’ve got to bear in mind that the study is observational, and so (as the press release does clearly say) we can’t draw any firm conclusions about cause and effect.  In particular we can’t conclude that bending over at work, or walking at work, are the cause of an increased miscarriage risk.  They could be the cause, or part of the cause, but they might not be.

“The problem is that women who differ in the amount of bending and walking at work also differ in terms of other factors, and it could be those other factors that are the real cause of differences in miscarriage rates, in whole or in part.

“The researchers made some statistical adjustments to account for differences in other factors, as far as they could, but that could be done only for factors on which they had data.  They point out in particular that they had no data on how much individual mothers smoked, and that smoking is a known risk factor for miscarriage.  They also mention a lack of data on other health conditions in the mothers.  This is why the researchers call for more research to get a better picture of what might be going on.

“In a group of 100 pregnancies, like those studied in this research, there would be about 10 miscarriages.  In another similar group of 100 pregnancies, where the mothers bent forward at work on average for 1 hour more out of each 8 hours worked, the researchers estimate there would be about 13 miscarriages, though the cause of the increase isn’t necessarily the extra bending.  In yet another group of 100 pregnancies, like the first 100 but with an average of 1 hour more walking at work out of each 8 hours worked (but without the extra bending time), there would be an estimated 12 miscarriages – though again we can’t know whether the increase is caused by the extra walking time.

“Those risk increases are reasonably substantial, but without knowing more about cause and effect, it’s not clear what action (if any) should taken as a result.”

‘Occupational standing, walking and forward bending during pregnancy and the risk of miscarriage: a Danish nationwide, register-based, cohort study’ by Hannah Nørtoft Frankel et al. was published in Occupational & Environmental Medicine at 23:30 UK time on Thursday 18 June 2026. 

DOI: 10.1136/oemed-2025-110712

Declared interests

Prof Asma Khalil: “None relevant to this study.”

Prof Andrew Shennan: “No conflicts.  Professor Shennan has published research on exercise in pregnancy.”

Prof Kevin McConway: “I have no conflicts of interest to declare.”