Morning sickness, also known as nausea gravidarum, nausea/vomiting of pregnancy (NVP), emesis gravidarum or pregnancy sickness is a condition that affects over 50% of all pregnant females. The woman feels nauseous, sometimes vomits and is often tired. Women who use hormonal contraception or HRT (hormone replacement therapy) may also have morning sickness symptoms.
Typically, morning sickness occurs in the early hours of the morning, and gradually improves as the day progresses, hence the name. However, some experts say that the term is a misnomer as it can come on at any time of day. The nausea may be mild, or severe enough to induce vomiting.
Sometimes symptoms may be so severe that the woman suffers from dehydration, weight loss, alkalosis (a dangerous drop in the normal acidity of the blood) and hypokalemia (low blood potassium). When symptoms are very severe, the condition is called hyperemesis gravidarum, and develops in approximately 1% of all pregnancies.
According to the National Health Service (NHS), UK, about 28% of women experience nausea without vomiting.
If nausea and vomiting is to occur it will usually do so during the 6th week of pregnancy, but in some cases it may strike during the second week. For many women the symptoms of morning sickness are their first signs of pregnancy. Most pregnant women find that the morning sickness improve after the 12th week of pregnancy. Unfortunately, for some women symptoms persist throughout their pregnancy.
In the vast majority of cases, morning sickness, although an unpleasant experience, has no health risk for the baby, and is a normal part of pregnancy. In fact, some studies indicate that morning sickness during pregnancy often bodes towards a healthy pregnancy, with lower rates of miscarriages and still births, compared to pregnancies with no nausea and/or vomiting.
Some dietary changes, as well as getting plenty of rest, are usually all that is needed to treat morning sickness.
Although viewed romantically and humorously, morning sickness can seriously affect the mother's quality of life and how she goes about her daily activities. Women who are able to receive the support of family and friends tend to cope much better.
Symptoms of morning sickness
Morning sickness is most common during the first trimester of pregnancy.
A symptom is something the patient feels and reports, while a sign is something other people, such as the doctor detect. For example, pain may be a symptom while a rash may be a sign.
Morning sickness may include nausea and vomiting, or just nausea without vomiting. It is much more common during the first trimester of pregnancy.
According to The Mayo Clinic, USA, pregnant women should call their doctor or health care provider if:
- Symptoms of nausea or vomiting are severe
- They pass only a small amount of urine
- Their urine is a dark color
- They cannot keep liquids down
- They feel dizzy when they stand up
- They faint when they stand up
- Their heart races
- They vomit blood
What causes morning sickness?
The consensus of experts varies on what the causes of morning sickness are. Most agree that hormonal changes probably play a role.
Estrogen levels - experts believe it is partly due to an increase in the circulating level of estrogen, a hormone. Estrogen levels may be 100 times higher during pregnancy, compared to levels found in a woman who is not pregnant. However, there is no evidence to show a difference in estrogen levels between pregnant women with nausea and/or vomiting and those without.
Progesterone levels - when a woman is pregnant her levels of progesterone, another hormone, also rise. High levels of progesterone relax the uterus (womb) muscles to prevent early childbirth. However, it may also relax the stomach and intestines, resulting in excess stomach acids and GERD (gastroesophageal reflux disease, or acid reflux).
Hypoglycemia - low blood sugar, caused by the placenta draining energy from the mother's body. However, there are no studies to prove this.
Levels of human chorionic gonadotropin (hCG) - this is a hormone produced in pregnancy that is made by the developing embryo not long after conception and later by part of the placenta. The hormone is released to prevent the disintegration of the corpus luteum of the ovary, thus maintaining progesterone production which is vital for pregnancy. Some experts suggest there may be a link between hCG and morning sickness.
Sense of smell - during pregnancy there may be an increase in sensitivity to odors, which may overstimulate normal nausea triggers.
Evolutionary survival adaptation - some experts suggest that morning sickness may be an evolutionary adaptation which protects pregnant mothers and their babies from food poisoning - an evolved trait that protects the fetus against toxins ingested by the mother. If the woman with morning sickness does not feel like eating foods which may be potentially contaminated, such as poultry, eggs or meat, and prefers foods with a low contamination risk, such as rice, bread and crackers, the survival chances for her and her child are improved.
Some scientists have found a good correlation between toxin concentrations in foods, and the tastes and odors that cause revulsion.
Adult humans have defenses against plant toxins, including a wide range of detoxification enzymes produced by the liver and the surface of tissues of various other organs. In the developing baby these defenses are not yet fully developed, and even relatively small amounts of toxins could be harmful.
The developing baby's vulnerability to toxins peaks at about three months, more or less the time of the peak of susceptibility to morning sickness (after which symptoms tend to go down).
As a woman's immune systems are suppressed during pregnancy (probably so that her body does not reject the baby), this evolutionary survival adaptation is also seen as helping the mother.
If it is true that morning sickness is a defense mechanism against the ingestion of harmful toxins, some experts suggest that perhaps prescribing anti-nausea medication to pregnant women may not be a good idea. In areas of the world where the mother has access to high-quality foods (with a low risk of contamination), the risk is probably small.
Risk factors for morning sickness
A risk factor is something which increases the likelihood of developing a condition or disease. For example, obesity significantly raises the risk of developing diabetes type 2. Therefore, obesity is a risk factor for diabetes type 2.
Any woman who is pregnant has the potential for developing morning sickness. However, the risk is higher if:
- Before the pregnancy the woman had experienced nausea or vomiting from: motion sickness, migraines, some tastes or smells, or birth control pills.
- The woman had experienced morning sickness in a previous pregnancy.
- The woman is expecting twins, triplets, quads, etc.
On the next page we look at how morning sickness is diagnosed, the options for treating and relieving morning sickness and the possible complications caused by it.