Science 'exonerates' morning sickness

Morning sickness was once considered an abnormal sign, but new research shows that it is actually an evolutionary biological response that helps pregnant women avoid risks and protect the fetus.

Morning sickness has long been considered a nightmare for many pregnant women.

According to the US National Institutes of Health (NIH), about 80% of women worldwide in the early stages of pregnancy experience morning sickness, nausea, vomiting or sensitivity to food smells. Contrary to popular belief that this is a sign of “problems”, research from the University of California, Los Angeles (UCLA) confirms that this is a natural biological reaction.

During pregnancy, the mother's immune system faces a special challenge: it must both protect the body from pathogens and not attack the fetus, which carries half of its genes from the father, meaning it is "partly foreign" to the mother's body.

“The mother has to maintain a delicate balance between keeping herself and her fetus safe, while avoiding an overactive immune response that could harm the fetus,” said anthropology professor Molly Fox, lead author of the study published in the journal Evolution, Medicine and Public Health.

The researchers found that this balance is maintained by a combination of specific inflammatory responses and adaptive behavioral mechanisms. Symptoms such as nausea, vomiting, or aversion to the taste of certain foods are considered “evolutionary strategies” to keep mothers away from potentially harmful foods, especially in the first 3-6 months, when the fetus is most vulnerable.

To investigate the connection, scientists followed 58 Latina women in Southern California from early pregnancy until postpartum. The mothers had blood samples analyzed for immune molecules called cytokines and also filled out surveys about morning sickness symptoms and odor and food aversions.

The results showed that 67% of women felt nauseous, 66% vomited, and 64% had an aversion to the smell of tobacco or meat. Notably, those with these aversions also had a marked increase in pro-inflammatory cytokines, a sign of an overactive immune system.

“Morning sickness is not an abnormal sign. On the contrary, it reflects a healthy immune response, which helps to better protect mother and baby,” explains co-author Professor Daniel Fessler.

Researchers compare this phenomenon to the way people today label foods like undercooked meat or soft cheese, which pose a high risk of poisoning to pregnant women. In nature, nausea and food aversions are “biological warning labels” that evolution has programmed to limit risk.

In addition to its scientific value, this finding also has social significance. Recognizing morning sickness as a normal biological response can help reduce workplace stigma and pave the way for practical support policies such as adjusting working hours and allocating appropriate health benefits for pregnant women.

The team of scientists said these results are just the beginning. Further studies could help doctors provide less invasive pregnancy care and predict the risk of abnormalities early.

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MINH HAI

Source: https://tuoitre.vn/khoa-hoc-giai-oan-cho-om-nghen-20250930154508037.htm