There is no singular cause for miscarriage, but many cases are put down to chromosomal abnormalities in the developing foetus or maternal health. In recent years, researchers have explored the effects of other environmental factors on the gestation period of expectant mothers. According to new findings, certain seasons of the year may increase the risk of miscarriage due to exposure to heat.
The new study revealed that the risk of miscarriage, in North America, is raised by 44 percent in late August compared to late February.
The findings, published in the journal Epidemiology, stem from research on the seasonal differences in miscarriage risk.
Doctor Amelia Wesselink, research assistant professor of epidemiology at Boston University of Public health, said: “Any time you see seasonal variations in outcomes, it can give you hints about causes of that outcome.
“We found that miscarriage risk, particularly risk of ‘early’ miscarriage before eight weeks of gestation was higher in the summer.
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“Now we need to dig into that more to understand what kinds of exposures are more prevalent in the summer, and which of these exposures could explain the increased risk of miscarriage.”
The result also showed that the risk of miscarriage during any week of pregnancy was 31 percent higher in late August compared to late February.
People in the South and Midwest of the US were more likely to experience loss of pregnancy in late August and early September.
Geographically, these were the regions where the summer months are hottest, reinforcing the theory that exposure to heat may be the cause.
The latest is one of many to arouse suspicion that heat may be a significant risk factor for early miscarriage during the summer months.
This theory chimes with a study conducted by the National Institutes of Health, which found women exposed to extreme heat waves during the first seven weeks of pregnancy were 11 percent more likely to go into labour early.
“Few studies have examined the association between heat and miscarriage risk, so this is definitely a topic that warrants further exploration,” added Doctor Wesselink.
“We know that heat is associated with a higher risk of other pregnancy outcomes, such as preterm delivery, low birth weight and stillbirth, in particular.
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“Medical guidance and public health messaging – including heat action plans and climate adaptation policies – need to consider the potential effects of heat on the health of pregnant people and their babies.”
Exposure to extreme heat early in pregnancy is also believed to be the culprit behind the preterm birth, according to previous research.
Exposure to hot temperatures can occur in several different settings, however, not just hot weather.
Hot tubs, saunas, and very hot baths are sometimes advised against as these all raise the body’s core temperature, particularly when enjoyed for longer periods of time.