Nausea and vomiting in pregnancy

Many pregnant women feel sick or vomit during early pregnancy. In most cases it is mild and does not need any specific treatment. In more severe cases, an anti-sickness medicine is sometimes used. Lack of fluid in the body (dehydration) is a complication in severe cases. See a doctor if you suspect that you are becoming dehydrated, or if you are struggling with the symptoms.

What is morning sickness?

Most pregnant women feel sick and vomit during early pregnancy. So, it can be considered a normal part of pregnancy. It is often called morning sickness but symptoms can occur at any time, day or night - not just in the morning. Symptoms are mild in most cases. Feelings of sickness (nausea) typically come and go. They usually last for between one and four hours at a time. Some women have more severe symptoms and have frequent and/or longer bouts of vomiting. Some have nausea without vomiting.

When does morning sickness start?

Sickness and vomiting usually start between the fourth and seventh weeks of pregnancy. In 9 out of 10 women, the symptoms have gone by 20 weeks of pregnancy. However, some pregnant women have some sickness throughout their entire pregnancy.

Sickness and vomiting in pregnancy can be a difficult problem to cope with. It can interfere with a pregnant woman's life. It can affect mood, work, relationships, the home situation and people's ability to care for their family. Support and help from family and friends can make coping easier.

What is hyperemesis gravidarum?

For a very few pregnant women (less than 1 in 100 pregnant women), the sickness and vomiting are prolonged and very severe. This causes them to become lacking in fluid in the body (dehydrated) and to lose weight. They may also develop vitamin deficiencies. Because they are not able to eat, the pregnant woman can develop signs of starvation. This is shown by looking for the presence of substances called ketones in the urine (using a simple test on a sample of urine). It's normal to have ketones in the urine if people are fasting for another reason. However, in the setting of nausea and vomiting in pregnancy, ketones suggest the body is being forced to break down fat for energy because the vomiting is preventing a woman from getting enough to eat.

This severe vomiting in pregnancy is called hyperemesis gravidarum. These women often need to be admitted to hospital for intravenous fluids and other treatment.

What causes morning sickness?

The exact cause of the sickness is not known. It is probably due to the hormonal changes of pregnancy. Feelings of sickness (nausea) and vomiting tend to be worse in twin and other multiple pregnancies.

There are several things that can make nausea and vomiting in pregnancy more likely. These include the following:

• Having a female baby.

• Being in the first pregnancy.

• Having had nausea and vomiting in previous pregnancies, or having a family history of nausea and vomiting (in mothers or sisters).

• Having twins or another multiple pregnancy.

• Having a history of motion sickness.

• Having a history of migraines.

• Having experienced nausea when taking the combined oral contraceptive pill.

• Having obesity.

Can morning sickness affect the baby?

Not usually. Mild-to-moderate symptoms of nausea and vomiting are unlikely to cause any problems to the baby. It might actually be a sign that the placenta is working well - rates of miscarriage are actually lower in women with mild-moderate nausea and vomiting, compared to women who don't get symptoms.

Severe symptoms (hyperemesis gravidarum), if untreated, do seem to increase the risk of some problems, such as preterm labour and low birth weight. However, this doesn't affect everyone with hyperemesis gravidarum.

Do I need any investigations?

For mild feelings of sickness (nausea) and vomiting during pregnancy, tests or investigations are not usually needed.

Investigations may be needed:

• If symptoms become more severe.

• If you are not able to keep any food or fluids down.

• If you start losing weight.

• To look for other causes of nausea and vomiting, if there are symptoms and signs suggesting something else (such as a urine infection) - see 'other causes of vomiting' at the end of this leaflet.

Investigations may include a urine test to look for ketones in your urine (as described above) and some blood tests.

What helps with morning sickness?

In most cases, as the symptoms are often mild, no specific treatment is needed. However, there are certain things that can be tried to help relieve symptoms. They include:

Eating small but frequent meals

Foods high in carbohydrate are best, such as bread, crackers, etc. Some people say that sickness is made worse by not eating anything at all. If you eat some food regularly, it may help to ease symptoms. Eating a plain (or ginger) biscuit about 20 minutes before getting up is said by some women to help. Cold meals may be better if nausea is associated with food smells.

Ginger

Some studies have shown that taking ginger tea, capsules or syrup may be effective for relieving feelings of sickness (nausea) in pregnancy. Food containing ginger may also help.

Avoiding triggers

Some women find that a trigger can set off the sickness. For example, a smell or emotional stress. If possible, avoid anything that may trigger symptoms.

Having lots to drink

Avoiding lack of fluid in the body (dehydration) may help. Drinking little and often rather than large amounts may help to prevent vomiting. Try to aim to drink at least two litres a day. Water is probably the best drink if you are feeling sick. Cold and sweet drinks can sometimes make symptoms worse in some people.

Rest

Make sure that you have plenty of rest and sleep in early pregnancy. Being tired is thought to make nausea and vomiting during pregnancy worse.

Acupressure

P6 (wrist) acupressure may be effective to reduce nausea and vomiting in pregnancy. Acupressure is the application of pressure only and does not need needles. There is not yet very much evidence on how effective this is in pregnancy.

Note: generally, you should not use over-the-counter remedies for sickness and vomiting whilst you are pregnant. This is because their safety and effectiveness for sickness and vomiting in pregnancy is uncertain.

When are anti-sickness medicines needed?

Most pregnant women manage to eat and drink enough, and can manage symptoms without anti-sickness medicines. However, an anti-sickness medicine may be advised if symptoms are persistent and severe, or do not settle with the above measures.

As a precaution, medicines in pregnancy are only used if there is a clear benefit (such as treating distressing symptoms that can't be managed in a different way, or giving a significant benefit to the mother or baby's health), and if there is good reason to believe the medicines are safe in pregnancy (or that the risks are known, and acceptable).

Doctors should discuss the risks and benefits of medicines in pregnancy to help women come to the right decision for them. For people with hyperemesis gravidarum especially, the small risks of some types of antisickness medicine might be outweighed by the benefit they have on the physical and mental health of the pregnant woman, and help protect the baby.

There are several different medicines that can be used to treat nausea and vomiting in pregnancy, including:

• A combination of doxylamine and pyridoxine (vitamin B6), currently sold under the trade name Xonvea®. This is a relatively new drug in the UK, but the ingredients have been widely used elsewhere, with good evidence that it is safe. It can improve symptoms of nausea and vomiting. It's also the only drug in the UK that is specifically licensed to treat nausea and vomiting in pregnancy.

  • Pyridoxine (vitamin B6), on its own, is used as a treatment in some places, such as the USA. However, there isn't much evidence to show that it actually works. It's therefore not used as a treatment for nausea and vomiting in the UK.

• Other good initial options are medicines like promethazine, cyclizine, prochlorperazine or chlorpromazine.

• If these don't work, medicines like metoclopramide, domperidone or ondansetron can be used. These are backup options only, because they have some additional risks:

  • Metoclopramide can cause short-term nerve and movement problems, so should only be used for a maximum of five days.

  • Domperidone can cause dangerous problems with the heart rhythm (although this is probably extremely unlikely in pregnant women), so should only be used for a maximum of seven days.

  • Ondansetron might be linked to an increased risk of cleft lip and cleft palate in the baby, although this risk is low (at least 998 of every 1,000 babies exposed to ondansetron in the womb are born without this problem). There is some concern that it might also be linked to heart problems in the baby, although some other evidence has been reassuring - more research is needed to say for sure.

• Steroid medicines can be given in severe cases of hyperemesis gravidarum, if all other treatments haven't worked. These would only be given by an obstetric specialist in hospital.

If medication is used, it's best to use the lowest possible dose that controls symptoms for the shortest possible time. However, some women may need to take medication for several weeks, or longer.

Aside from Xonvea®, none of the drugs listed above are specifically licensed for use in pregnancy in the UK. The manufacturers of these drugs often state that they should be used with caution in pregnancy, or advise against using them at all. This often appears on the leaflet supplied with the medicines. However, medical experience and research has given a good idea of the risks and benefits of these medicines, and they are generally accepted as safe options to use if needed. See the Best Use of Medicines in Pregnancy link in Further Reading for more.

What if these treatments do not work very well?

Hospital care is needed to give fluids by a drip in a small number of women. Hospital care may be needed for women who don't respond to initial tablet medicines, or can't keep them down. Women may need to be admitted to hospital if they become ill, lose weight or become significantly lacking in fluid in the body (dehydrated).

Hospitals can also give anti-sickness medication as an injection, or in a drip, which might work better as an initial treatment if women cannot keep sickness tablets down otherwise.

Vitamins given by a drip are sometimes given to women who have severe symptoms, to treat starvation.

Very rarely, feeding with a tube into the stomach or via a drip might be needed.

Some medicines - like steroids - would only be given under direction of an obstetric specialist in hospital.

Other causes of vomiting

Vomiting can be caused by other problems, and is not always due to pregnancy. Pregnant women can still get other illnesses, such as a urinary tract infection. Contact a doctor urgently if you develop any symptoms that you are worried about, particularly any of the following symptoms:

• Very dark urine or not passing any urine for more than eight hours.

• Stomach pains.

• High temperature (fever).

• Pain on passing urine.

• Headache.

• Runny stools (diarrhoea).

• Yellow skin (jaundice).

• Severe weakness or feeling faint.

• Blood in your vomit.

• Repeated, unstoppable vomiting.