Pregnant women thinking about moving might be better off waiting until later in their pregnancy, suggests a new US study, which found that moving house during the first three months of pregnancy appears to be linked to a higher risk of premature birth and low birth weight.
The new study, by researchers at the University of Washington's School of Public Health, looked at babies born to 28,011 mothers who had moved during the first three months of pregnancy -- known as the first trimester -- and at 112,367 mothers who hadn't moved house during early pregnancy.
The researchers chose to focus on the first trimester, as previous studies have suggested that major stressors during early pregnancy, such as natural disasters, bereavement or job loss, have a bigger impact on a baby's health than those experienced later in pregnancy.
The findings, published online in the Journal of Epidemiology & Community Health, showed that women who moved house during the first three months of pregnancy had a 37 percent increased risk of having a baby with a low birth weight, a 9 percent increased risk of giving birth to a smaller-than-expected size baby, and a 42 percent increased risk of having a premature birth compared with those who didn't move during this period.
The team also found that women who moved early in pregnancy were more likely to be younger, unmarried, less well educated, to live in areas with lower average levels of household income, to smoke during pregnancy, and to have had other children, compared to women who hadn't moved in the first trimester.
Although these factors are linked to the health problems the researchers were investigating -- low birth weight, premature birth and smaller than expected size babies -- the findings still held true even after taking into account these potential risk factors, with the differences seen across women in all social and economic groups.
The reasons why moving house during the first trimester could increase these risks is still unclear, however the researchers suggest that the physical strain of moving, disruptions to social support and access to healthcare, and a biological stress reaction may all play a role.
The team note that as this was an observational study, they could not establish a cause-and-effect relationship, adding that despite the large sample size being a strength of the study, it did have its limitations. For instance, the team did not determine reasons for the move or whether it resulted in living in a better or worse area, both of which could impact the results.
However, with up to 25 percent of pregnant women estimated to move during their pregnancy, the researchers said, "Despite these limitations, our results yield important insights regarding moving during pregnancy."
"Regardless of whether the negative impact of moving is driven by the stress from the move itself, stressful situations leading to a move, or disruption of care because of the move, asking patients about plans to move and using that as an opportunity to counsel patients on stress mitigating techniques and care continuity may be beneficial," they concluded.