According to Sweet (1999) seventy to ninety percent of pregnant women experience some form of nausea, however although there has been much research, there are still no form conclusions as to the causes.
It is thought that the sickness is generally caused by the increased levels of Human Chorionic Gonadotrophin (HCG) secreted by the placenta and the progesterone secreted by the ovaries.
If a woman is being sick several times a day there is a danger of dehydration and help should be sought. Physical manifestations of dehydration are: increased pulse rate (above 120 bpm), low blood pressure, loss of skin elasticity, dry mouth, infrequent urination and ketotic breath (like pear drops or nail varnish).
There are also other conditions in pregnancy that make the nausea worse including; multiple pregnancies, pregnancy induced hypertension, hydatidiform mole, placental abruption and hydramnios (an excess of amniotic fluid).
Symptoms often associated with Morning Sickness are anything that can affect the other senses of smell, taste, touch and see. Some women feel nausea on moving such as changing position from sitting to standing. Many women also experience extreme fatigue during the early part of pregnancy and may also suffer from any of the following:
Aversion to food
Intense nausea may be experienced with food that women may have previously enjoyed such as tea, coffee, toast etc…
Experiencing a strong urge or desire to eat certain foods is common and can be overwhelming. It is not unusual for the object of the craving to be something that is not usually enjoyed but is usually something the body needs.
An unpleasant cooper like taste occurring in the early stages of pregnancy. If it is experienced as a strong effect, it will spoil the taste of food. Not all cases are as severe and are usually experienced as a spectrum in intensity from moderate to severe.
This is a desire to eat something that is inedible such as coal.
This is often experienced by women especially in the later stages of pregnancy, although in the early stages it may be experienced as a burning sensation coupled with nausea.
Experienced as excess gas created by the stomach and associated with nausea.
Women who experience intense hunger and eat may managed to resolve feeling of nausea or conversely may vomit straight away.
Smells that were previously enjoyed by a woman in pregnancy may bring on intense nausea and vomiting.
Tiredness is extremely common in early pregnancy and may become overwhelming where the woman is still working, looking after children or in a first pregnancy.
In Chinese medicine
When Blood accumulates in the Chong Mai (the vessel that supplies the uterus with Blood), it may reach a point where it overflows and results in nausea. This may happen sooner if there are pre-existing digestive issues.
Emotions are considered by the Chinese to be the internal causes of disease and can have a major effect on nausea and sickness levels, since they are linked directly to the various organs in the body.
Anger, which may be caused by repressed frustration and resentment will cause Liver Qi to stagnate, affecting the Spleen to cause diarrhoea and the Stomach to cause obstruction, pain in the epigastrium, nausea and belching. The greater the Liver Qi stagnation, the worse the symptoms and the greater likelihood of vomiting.
Worry will affect the Spleen and Stomach and will cause Qi to stagnate and food to be retained in the Stomach. If there is any over exertion this will affect the Stomach and Spleen and cause dull pain, tiredness and muscle weakness. Working long hours can cause mental strain, which will cause a deficiency of Stomach Qi (specifically Yin), which can also happen through irregular eating patterns over many years.
Fear causes Qi to sink and since Kidney Qi has a profound effect on the Chong Mai and Ren Mai (Penetrating & Directing Vessels – integral in ensuring the health of the fetus), there can be a strong chance of miscarriage.