Aversion to and avoidance of certain foods also peaks during the first trimester for many pregnant women.Women who vomit are significantly less likely to miscarry than those who experience nausea alone. Women who experience morning sickness are significantly less likely to miscarry than women who do not.Among women who experience morning sickness, symptoms peak precisely when embryonic organogenesis (organ development) is most susceptible to chemical disruption – between week 6 and week 18 of pregnancy.(Small amounts of these chemicals might even be beneficial because of their antioxidant properties and trace elements.) But during pregnancy, according to the Cornell biologists, women with morning sickness are shielding the developing unborn from the harsh chemicals by vomiting and by learning to avoid certain foods altogether until the fetus develops beyond the most susceptible stage. These chemicals are secondary compounds that plants make to defend themselves against disease and insects.Īlthough phytochemicals have no known nutritive function for humans, most people tolerate their presence in food. Those developing structures and organ systems – such as arms and legs, eyes and the central nervous system – at this critical stage of a new life could be adversely affected by the teratogenic phytochemicals in some food plants," Sherman says. "At that same time, in the first trimester of pregnancy, the cells of the tiny embryo are differentiating and starting to form structures. We should change the name to wellness insurance."įlaxman, a Cornell biology graduate student, says the analysis of hundreds of studies covering tens of thousands of pregnancies suggests that morning sickness and the aversion to potentially harmful foods is the body's way of preserving wellness of the mother at a time when her immune system is naturally suppressed (to prevent rejection of the child that is developing in her uterus) and has reduced defenses against food-borne pathogens.īy creating food aversion, NVP also protects against toxins from microorganisms and other teratogenic (fetal organ-deforming) chemicals, Sherman says.
"'Morning sickness' is a complete misnomer," says Sherman, professor of neurobiology and behavior at Cornell and co-author of the report, "Morning Sickness: A Mechanism for Protecting Mother and Embryo." "NVP doesn't occur just in the morning but at any time during the waking hours, and it's not a sickness in the pathological sense. Sherman and Flaxman believe their exhaustive analysis and synthesis of dozens of studies is the first to gather compelling evidence that morning sickness protects both the unborn and the mother-to-be. The finding helps explain why many pregnant women develop an aversion to meats, as well as to certain vegetables and caffeinated beverages, in early pregnancy and prefer bland-tasting foods instead. Sherman report that NVP (for nausea and vomiting in pregnancy, as morning sickness is known in medical terms) serves a beneficial function.
In the latest issue of The Quarterly Review of Biology (Vol. That is the conclusion of two Cornell University evolutionary biologists who examined the outcomes of thousands of successful and unsuccessful pregnancies.
Mother-model Mirka Pospisil delivered a healthy baby girl June 4, 2000.Īs unpleasant as it is, the nausea and vomiting of "morning sickness" experienced by two-thirds of pregnant women is Mother Nature's way of protecting mothers and fetuses from food-borne illness and also shielding the fetus from chemicals that can deform fetal organs at the most critical time in development. Thereafter the frequency declined gradually. The incidence of NVP symptoms increased until weeks 9-14, when 60-70 percent of the women experienced nausea and 30-40% vomited.