Overview, Causes, & Risk Factors

Morning sickness is nausea or vomiting during the first 20 weeks of pregnancy. More than half of pregnant women have morning sickness during the first trimester. It usually goes away by the second trimester. When morning sickness is severe, it is called hyperemesis gravidarum.

What is going on in the body?

The cause of morning sickness is not well understood, but hormones seem to be involved. The hormone called human chorionic gonadotropin, or HCG, is produced by the fertilized egg and by the chorionic villi. These are the fingerlike projections of the developing placenta. HCG is needed to keep the pregnancy going until the placenta has developed enough. HCG levels are usually highest in the first 12 weeks of pregnancy.

What are the causes and risks of the condition?

A woman with high levels of HCG is more likely to have morning sickness. High levels of HCG are seen in multiple pregnancies, such as twins and triplets. A woman who has had morning sickness in a previous pregnancy is more likely to have it again.

Increased HCG levels can be caused by a molar pregnancy, or tumor of the placenta. This condition should be ruled out in women with morning sickness. There is some evidence that psychological factors, such as ambivalence toward pregnancy, can increase the risk of morning sickness.

Symptoms & Signs

What are the signs and symptoms of the condition?

There is a huge variation in how bad the symptoms of morning sickness are. Some women just feel queasy in the morning and feel fine by noontime. They are able to perform their daily activities. Others suffer from nausea and vomiting that can last all day. They find ordinary work during pregnancy almost impossible.

Some women have symptoms of morning sickness within days of conception. But the average time from the last menstrual period to the start of nausea is about 5 weeks.

The symptoms of morning sickness include:

Diagnosis & Tests

How is the condition diagnosed?

Diagnosis of morning sickness begins with a history and physical exam. Urinalysis may be done, as well as blood tests to check for dehydration.

Prevention & Expectations

What can be done to prevent the condition?

Morning sickness cannot always be prevented. Some women find diet and lifestyle changes helpful in reducing symptoms. The mother is advised to avoid things that produce the symptoms, such as certain foods and smells. She should eat smaller, more frequent meals. Dry crackers or toast, tea, cold liquids, and carbonated drinks may help lessen morning sickness. Eating before getting out of bed may help prevent the nausea.

What are the long-term effects of the condition?

Prolonged morning sickness can cause weight loss, dehydration, salt imbalances, and malnutrition. If these are not treated, they can lead to liver, kidney, heart, and brain damage to the mother and the fetus.

Severe morning sickness can strain a marriage and hinder job performance. Most women feel better after the start of the second trimester, and the pregnancy can continue with no further problems.

What are the risks to others?

There are risks to the fetus if morning sickness is severe enough. Severe morning sickness, or hyperemesis gravidarum, can cause low birth weight and fetal growth retardation. The blood flow to the placenta and fetus is also decreased Less oxygen and nutrients are delivered to the baby. Low birth weight is often linked with poorer mental function and reduced overall health of the baby.

Treatment & Monitoring

What are the treatments for the condition?

If the morning sickness is quite severe, intravenous fluids may be needed to correct fluid and electrolyte imbalances and dehydration. Severe morning sickness may even require hospitalization.

Education and emotional support are very helpful for the woman with morning sickness. A nutritionist who routinely works with pregnant woman may help. A social worker may be asked to get involved with the family. A woman with morning sickness needs reassurance that it is OK to change her schedule to allow for more rest. Antinausea medicines may be needed to keep the woman from vomiting.

What are the side effects of the treatments?

The FDA does not approve medicines used for nausea during pregnancy. There is the possibility of harmful side effects for the fetus.

What happens after treatment for the condition?

Morning sickness usually gets better by the beginning of the second trimester.

How is the condition monitored?

Morning sickness is monitored at prenatal visits. Any new or worsening symptoms should be reported to the healthcare provider.