Morning sickness

Morning sickness, also called nausea and vomiting of pregnancy (NVP), is a

Morning sickness affects about 70–80% of all pregnant women to some extent.[4]^[5] About 60% of women experience vomiting.^[2] Hyperemesis gravidarum occurs in about 1.6% of pregnancies.^[1] Morning sickness can negatively affect quality of life, result in decreased ability to work while pregnant, and result in health-care expenses.^[3] Generally, mild to moderate cases have no effect on the fetus, and most severe cases also have normal outcomes.^[1] Some women choose to have an abortion due to the severity of symptoms.^[1] Complications such as Wernicke encephalopathy or esophageal rupture may occur, but very rarely.^[1]

Signs and symptoms

About 66% of women have both nausea and vomiting while 33% have just nausea.^[1] Symptoms of both nausea and vomiting will normally climax around 10 and 16 weeks of pregnancy, subsiding around 20 weeks.^[8] However, after around 22 weeks, up to 10% of women continue to have lingering symptoms.^[8]

Cause

The cause of morning sickness is unknown but may relate to changing levels of estrogen and the hormone

Nausea and vomiting may also occur with molar pregnancy.^[10]

Morning sickness is related to diets low in cereals and high in sugars, oilcrops, alcohol and meat.^[11]

Pathophysiology

Hormone changes

• An increase in the circulating level of the hormone
  hormone replacement therapy
  .
• An increase in
  stomach acids and gastroesophageal reflux disease (GERD)
  .
• An increase in human chorionic gonadotropin. It is probably not the HCG itself that causes the nausea. More likely, it is the HCG stimulating the maternal ovaries to secrete estrogen, which in turn causes the nausea.^[14]

Defense mechanism

Morning sickness may be an evolved trait that protects the fetus against toxins ingested by the mother. Independent Scholar-Biologist Margie Profet from Seattle was one of the first to investigate the morning sickness-mystery. She argued 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.^[15] A woman and her embryo are very vulnerable to toxins during pregnancy. By reducing exposure to such chemicals, morning sickness reduces impairments on normal embryonic development and increases the reproductive success of the mother and survival success of both the mother and her offspring. Evidence in support of this theory includes:^[16][11]

• Morning sickness is very common among pregnant women, which argues in favor of its being a functional adaptation and against the idea that it is a pathology.
• Fetal vulnerability to toxins peaks at around 3 months, which is also the time of peak susceptibility to morning sickness.
• There is a good correlation between toxin concentrations in foods, and the tastes and odors that cause revulsion.

Women who have no morning sickness are more likely to miscarry.^[17][18] This may be because such women are more likely to ingest substances that are harmful to the fetus.^[19]

In addition to protecting the fetus, morning sickness may also protect the mother. A pregnant woman's

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. In that period, the fetus is most at risk from damage to toxins and mutagens. These developments occur through week 6-18 which is in the same time frame in which the most nausea and vomiting of pregnancy (NVP) occurs. 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.[21]

Treatments

There is a lack of good evidence to support the use of any particular intervention for morning sickness.^[7]

Medications

A number of

Some studies support the use of ginger, but overall the evidence is limited and inconsistent.^{[3][7][9][27]} Safety concerns have been raised regarding its anticoagulant properties.^{[9][28][29][30]}

History

Thalidomide

In the late 1950s and early 1960s, the use of thalidomide in 46 countries by women who were pregnant or who subsequently became pregnant resulted in the "biggest man‐made medical disaster ever," with more than 10,000 children born with a range of severe deformities, such as phocomelia, as well as thousands of miscarriages.^[31][32]

Thalidomide was introduced in 1953 as a tranquilizer, and was later marketed by the German pharmaceutical company