Nausea and vomiting in pregnancy

Overview

Nausea (feeling sick) and vomiting affect most pregnant women, usually in the first weeks of pregnancy. It is often called morning sickness, but it can happen at any time of the day or night, and some women feel sick all day. Changes in pregnancy hormones are thought to be the main reason. For most women it gets better by about 16 to 20 weeks, and ordinary morning sickness does not raise the risk to the baby.

A small number of women, about 1 to 3 in every 100, get a much more serious form called hyperemesis gravidarum (HG). In HG the sickness is severe, the woman cannot eat or drink normally, and daily life is badly affected. It can lead to dehydration (not enough water in the body) and weight loss, and it may last longer, sometimes until the birth. HG is not caused by anything the woman has done, and it is not 'in her head'.

Milder sickness can often be helped with rest and changes to eating. If this is not enough, a doctor or midwife can prescribe anti-sickness medicines that have safety information for use in pregnancy. Women with HG may need a drip and care in a day unit or hospital. Sickness that starts after 16 weeks should be checked for other causes.

Symptoms

• Feeling sick, at any time of day or night, or all day
• Vomiting, sometimes many times a day
• Not being able to keep food or drink down (in severe cases)
• Feeling thirsty, tired, dizzy or light-headed
• Passing less urine, or dark, strong-smelling urine
• Weight loss
• Feeling low, anxious, alone or unable to cope

Causes and risk factors

Causes

• Hormone changes in early pregnancy, which are thought to be the main cause
• The exact cause of hyperemesis gravidarum is not known, but it is linked to pregnancy hormones
• A urinary tract infection (UTI) can also cause nausea and vomiting
• Carrying twins or more, or a rare abnormal growth in the womb called trophoblastic (molar) disease, which doctors check for with a scan
• Other illnesses, such as stomach, liver or thyroid problems, which doctors need to rule out

What makes it more likely

• Carrying twins or more babies
• Severe sickness or hyperemesis gravidarum in a past pregnancy
• A mother or sister who had hyperemesis gravidarum, or a family history of morning sickness
• Being prone to motion (travel) sickness
• A history of migraine
• Feeling sick in the past when taking contraceptive pills that contain oestrogen
• First pregnancy
• A body mass index (BMI) of 30 or more

Complications

Most morning sickness causes no lasting harm. Severe sickness can cause dehydration, weight loss, poor nutrition and an imbalance of body salts such as low potassium. Lack of vitamin B1 (thiamine) can lead to Wernicke encephalopathy, a rare but dangerous brain problem. Forceful vomiting can cause reflux, inflammation of the food pipe (oesophagitis) and tears in the oesophagus. Dehydration and lying in bed raise the risk of blood clots (deep vein thrombosis). Many women with HG have depression or anxiety. If the mother loses weight or gains too little, the baby may be born small or early, but HG is unlikely to harm the baby when it is treated well.

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Diagnosis

Doctors usually diagnose pregnancy sickness from the woman's story and an examination. Sickness should start before 16 weeks; if it starts later, other causes are looked for. A short score sheet (such as PUQE for mild to moderate sickness, or HELP for severe sickness) helps judge how bad it is and whether treatment is working. Weight and signs of dehydration are checked.

In more severe cases, a urine test looks for infection, and blood tests check body salts, kidney function, blood count and sugar. An ultrasound scan confirms the pregnancy is in the womb and checks for twins or molar pregnancy. Thyroid and liver tests may be slightly abnormal in HG and usually settle as it improves. Ketones in the urine should not be used to judge how dehydrated a woman is.

Treatment

1. For mild sickness, start with rest and changes to eating and drinking, such as small, frequent, plain meals and sipping fluids.
2. If this is not enough, see your doctor or midwife. They may prescribe a first-choice anti-sickness medicine, such as an antihistamine, a phenothiazine or a doxylamine with pyridoxine combination.
3. If the first medicine does not work, the doctor may switch to a second-choice medicine (such as ondansetron or metoclopramide) or combine medicines from different groups. Injections, suppositories or under-the-tongue forms can be used if you keep vomiting.
4. If you are dehydrated or cannot keep fluids down, you may be treated in a day unit or admitted to hospital for a drip of salt water with potassium, injected anti-sickness medicine and vitamins, including thiamine (vitamin B1).
5. Women admitted with HG are usually offered injections to prevent blood clots, or support stockings if injections are not suitable.
6. If sickness is still severe despite fluids and regular anti-sickness medicines, specialists may use steroids for a short time, and check for diabetes of pregnancy.
7. Reflux or stomach irritation can be treated with acid-reducing medicines, constipation should be treated, and emotional support or mental health care should be offered.

Medicines in Pakistan

Medicines a doctor may use, by group. Read the role: some are only for special cases. Each link opens our page for that medicine, with every brand and its official DRAP price. Your doctor decides which medicine and dose are right for you.

Also used (not yet in our price list): Doxylamine with pyridoxine, Promethazine, Prochlorperazine, Hydrocortisone injection (hospital use for severe HG), Thiamine (vitamin B1)

Self-care and prevention

Self-care

• Get plenty of rest, as tiredness can make sickness worse
• Avoid foods and smells that make you feel sick
• Eat dry toast or a plain biscuit before getting up in the morning
• Eat small meals often, choosing plain foods high in carbohydrate and low in fat, such as bread, rice, crackers and pasta
• Choose cold foods if the smell of hot food makes you feel sick
• Sip fluids little and often through the day
• If iron tablets seem to make your sickness worse, tell your doctor or midwife rather than stopping them on your own
• If you take regular medicines (for example for epilepsy) and vomiting makes them hard to keep down, ask your doctor about timing

Prevention

• There is no sure way to prevent pregnancy sickness, but getting help early can prevent dehydration and other problems
• If you had HG before, talk to your doctor early in the next pregnancy about starting anti-sickness medicine early, which is linked to milder sickness
• Plan support at home, such as help with childcare, so you can rest if sickness returns
• Repeat the things that helped you in a past pregnancy

Common questions

Can morning sickness harm my baby?

Ordinary morning sickness does not put the baby at extra risk. Hyperemesis gravidarum is unlikely to harm the baby if it is treated well. If the mother loses weight, the baby may be smaller at birth, so it is important to get help early.

Are anti-sickness medicines safe in pregnancy?

Several types of anti-sickness medicine have safety information for use in pregnancy, including in the first 12 weeks. Ondansetron used in the first 12 weeks is linked to a very small rise in cleft lip or palate, from about 11 to about 14 babies in every 10,000. Your doctor or midwife will choose the medicine, so do not start or stop any medicine on your own.

When does pregnancy sickness stop?

For most women it improves or stops by about 16 to 20 weeks. Hyperemesis gravidarum can last longer, and for some women it continues until the birth.

Will I get hyperemesis gravidarum again in my next pregnancy?

If you had HG before, you are more likely to get it again. Planning ahead and starting treatment early, with your doctor's advice, may make it less severe.

Is hyperemesis gravidarum caused by stress or anxiety?

No. The idea that HG is psychological is wrong. Low mood and anxiety are more often a result of HG than a cause, and support for your mental health should be part of your care.

Sources

1. NHS. Vomiting and morning sickness (2024).
2. NHS. Severe vomiting in pregnancy (n.d.).
3. Royal College of Obstetricians and Gynaecologists (RCOG), via NHS Scotland Right Decisions. The Management of Nausea and Vomiting in Pregnancy and Hyperemesis Gravidarum (Green-top Guideline No. 69) (2024).
4. NICE. Antenatal care: [R] Management of nausea and vomiting in pregnancy (evidence review, draft for consultation) (2021).
5. NHS Specialist Pharmacy Service. Nausea and Vomiting: treatment during pregnancy (n.d.).
6. Cochrane (republished in Sao Paulo Medical Journal, via PMC). Interventions for nausea and vomiting in early pregnancy (2010).
7. Journal of the Pakistan Medical Association. Frequency of Hyperemesis Gravidarum and associated risk factors among pregnant women (2020).

Prepared from the sources listed below by the MedInfoBase team. Last reviewed 16 October 2026. This page is general health information, not medical advice. It gives no doses and does not replace a doctor: talk to your doctor or pharmacist before starting, stopping or changing any medicine. How we write and check our pages.

Related conditions

Urinary tract infection (UTI)Anaemia in pregnancyGastro-oesophageal reflux disease (GERD)Acute gastroenteritis (diarrhoea and vomiting)Depression

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