Morning sickness protects the fetus

Morning sickness is one of the most common symptoms during pregnancy. Many expectant mothers wonder about this seemingly unnecessary expression. However, this misery has a certain meaning. Two evolutionary biologists say morning sickness protects both pregnant women and embryos at the time of the most vulnerable fetus.

Paul Sherman, Cornell professor of neurology and behavior and chairman of Weiss, said after examining two key theories (adaptive theory and non-adaptive theory) about why 2 / 3 women in the world - in addition to no other mammals - experience manifestations of nausea and vomiting during pregnancy, only a theory seems reasonable.

Sherman, a Darwinist medical expert - examines disease from an evolutionary perspective, saying: 'Our research has examined two theories and predicted the nature of conflict between parents and children. During pregnancy, it indicates that nausea and vomiting are beneficial by eliminating foods such as a strong flavored meat or vegetable . Historically and until now these foods may contain harmful toxins and microorganisms capable of damaging women as well as the fetus when fetal organs begin to develop. , easily damaged by chemicals'.

His research, conducted with Samuel M. Flaxman '98, Ph.D '05, an evolutionary behavioral researcher at the University of Colorado and a postdoctoral researcher at Cornell from 2005 to 2007, published in the July issue of The American Naturalist.

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He said other theoretical evidence suggests that morning sickness has protective benefits including:

- Expression of nausea and vomiting gradually decreases after 18 weeks of pregnancy, because the fetus is less dangerous by the impact of chemicals.
- Women with the most severe morning sickness have a lower rate of spontaneous abortion than other pregnant women.
- Historically, meat and bold-flavored vegetables often contain parasites, pathogens and toxins; These foods often cause morning sickness symptoms. Alcohol and tobacco, which can harm the fetus when the internal organs are forming also cause nausea.

Social communities that eat more meat and darker, more alcoholic foods have higher rates of morning sickness than societies with diets that are light-flavored plant products. The phenomenon of morning sickness is only in humans, because according to scientists, people have extremely varied meals compared to primates and other mammals.

If the theory is that morning sickness is an evolutionary irrelevant result of a struggle between a mother and fetus, the nausea must appear in the last 3 months, when the fetus is need more nutrition and blood. But this does not happen. It does not appear with any pregnancy. If morning sickness is the result of the fetus signaling its existence to the mother, it must appear in both humans and other mammals.

Sherman said: 'All of this leads us to conclude that morning sickness is a misuse of terminology. It doesn't just appear in the morning, and it's not a sickness. It may appear at any time of the day and it turns out to be beneficial - we can call it a form of evolutionary health protection. '

The current study was built from an article published in 2000 in the quarterly Biological Journal, in which Sherman and Flaxman studied results from thousands of pregnancies. In the study, they emphasized that in the seven traditional societies that do not have morning sickness, the meal is mainly light-bodied products, not meat and bold-flavored vegetables.