Nausea and vomiting in early pregnancy is so common that it can be considered a normal part of pregnancy. “Morning sickness” is not really that accurate because symptoms will often persist throughout the day. Up to 85% of women experience nausea in early pregnancy with approximately half of women vomiting as well. Symptoms usually begin between the fourth and seventh week and resolve in many women by the twelfth week and in most women by the twentieth week of pregnancy. A smaller number of pregnant women (approximately 0.3–1%), have a more severe form of nausea and vomiting – hyperemesis gravidarum, which is characterised by persistent vomiting, weight loss of more than 5%, ketones in urine, electrolyte abnormalities (low potassium) and dehydration.

While persistent nausea and vomiting in early pregnancy can be particularly debilitating for some women, it is not usually associated with any adverse pregnancy outcomes and in fact has been associated with lower rates of miscarriage.Hyperemesis gravidarum is on rare occasions associated with complications.

Nausea and vomiting in pregnancy is usually a self-limiting condition, however, hyperemesis gravidarum should be distinguished from other conditions that may cause persistent vomiting.

Nausea and vomiting that begins at or after 12 weeks gestation is unlikely to be caused by pregnancy so other causes should be investigated.

Rehydration may be required

Women who present with mild to moderate dehydration can be managed with oral fluids. Women who are severely dehydrated will require referral to hospital for IV fluids and other medication.

Causes and risk factors for nausea and vomiting in pregnancy

The causes of nausea and vomiting in pregnancy are unknown, however, it is thought to be associated with rising levels of human chorionic gonadotropin (hCG). Oestrogen is another suggested cause with the presence of a female foetus reported to increase the likelihood of severe nausea and vomiting during pregnancy.One study found that women who were in their first pregnancy, younger or were non-smokers were more likely to have nausea and vomiting in pregnancy.

Initial management in the majority of cases involves dietary and lifestyle advice 

The following recommendations may be useful and should be trialed first:

Dietary advice

• Drink small amounts often – dehydration can exacerbate nausea

• Trial different kinds of fluids – sometimes fluids such as flat lemonade or diluted fruit juice are managed better than water

• Avoid fatty or spicy food

• Avoid having an empty stomach – eat a light snack every one to two hours between meals

• Avoid very large meals

• Early morning nausea may be helped by eating a dry biscuit or cracker before getting out of bed

• Salty food such as potato chips or salted crackers may help, especially before meals

Lifestyle advice

• Eat well when feeling the best or whenever feeling hungry

• If the smell of hot food worsens nausea, try cold food instead, avoid cooking if possible or cook in well ventilated areas so that odours do not accumulate; ask for help from family and friends with cooking

• Lie down when nauseated

• Avoid stress

• Take pregnancy vitamins (including folic acid) at a good time of the day (when feeling well)

• Keep physical activity gentle, getting too hot may exacerbate nausea

Alternative therapies – ginger, pyridoxine and acupressure

Ginger has been shown in some studies to improve nausea and vomiting, however, there is conflicting data on the efficacy of ginger which may be the result of different preparations. Products which contain ginger such as tea, biscuits or confectionary may also be trialled. Ginger may cause reflux and heartburn in some people.

Pyridoxine (vitamin B6) is used first-line in many countries for nausea and vomiting in early pregnancy, however, there are large individual differences in its onset and action.

 Acupressure involves stimulation, either manually or with elasticized bands, of the P6 Neiguan point which is found on the inside of the forearm three fingerbreadths above the wrist. There is some evidence that P6 acupressure reduces symptoms of nausea and vomiting but some studies, which included sham acupressure, have found a strong placebo effect.

Manage other conditions such as heartburn

Drug treatment may be appropriate for women continuing to experience intolerable nausea and vomiting

Approximately 10% of women continue to experience significant nausea and vomiting during pregnancy, despite following dietary and lifestyle advice. In these cases, medications may be trialled.

Antiemetics can be taken according to when the pregnant woman experiences the most symptoms. For example, many women benefit from having a dose of antiemetic 30 minutes before getting out of bed to prevent vomiting while having a shower or after having breakfast. Late afternoon symptoms associated with tiredness may be improved by a second dose around 1–2 pm.