Morning sickness

[1][6] The cause of morning sickness is unknown but may relate to changing levels of the hormone human chorionic gonadotropin.

[8] The cause of morning sickness is unknown but may relate to changing levels of estrogen and the hormone human chorionic gonadotropin.

[2][9] Some have proposed that morning sickness may be useful from an evolutionary point of view -it may protect both the pregnant woman and the developing embryo just when the fetus is most vulnerable.

[10] Morning sickness is related to diets low in cereals and high in sugars, oilcrops, alcohol and meat.

Biologist Margie Profet believes that nausea and food aversions during pregnancy evolved to impose dietary restrictions on the mother in the early weeks of pregnancy, when the mother and the embryo are most immunologically vulnerable, to minimize fetal exposure to toxins such as mutagens and teratogens.

A pregnant woman's immune system is suppressed during pregnancy, presumably to reduce the chances of rejecting tissues of her own offspring.

[21] If morning sickness is a defense mechanism against the ingestion of toxins, the prescribing of anti-nausea medication to pregnant women may have the undesired side effect of causing birth defects or miscarriages by encouraging harmful dietary choices.

[16] Also, morning sickness is a defense mechanism because when analyzing embryonic growth, several critical periods are identified in which there is mass proliferation and cell division resulting in the development of the heart and central nervous system that are very sensitive.

This relationship between the time at which the embryo is most susceptible to toxins lines up exactly with when the most severe NVP symptoms are seen, suggesting that this NVP is an evolutionary response developed in the mother, to indicate the sensitivity of the fetus hence making her wary to her health and in turn protecting the fetus.

[7] A number of antiemetics are effective and safe in pregnancy including: pyridoxine/doxylamine, antihistamines (such as diphenhydramine), metoclopramide, and phenothiazines (such as promethazine).

[34][35] Thalidomide was introduced in 1953 as a tranquilizer, and was later marketed by the German pharmaceutical company Chemie Grünenthal under the trade name Contergan as a medication for anxiety, trouble sleeping, "tension", and morning sickness.

[38] While initially deemed to be safe in pregnancy, concerns regarding birth defects were noted in 1961, and the medication was removed from the market in Europe that year.