Nausea and Vomiting in Pregnancy - Including Hyperemesis

Nausea and vomiting are both common in early pregnancy. There is no evidence of fetal damage as a result of the nausea and vomiting.

Hyperemesis gravidarum occurs when vomiting becomes persistent and severe. Hyperemesis affects 1-2% of pregnancies and causes dehydration, electrolyte disturbance and ketosis. Without treatment hyperemesis may lead to central nervous system complications, liver failure and renal failure, but this is now rare in the developed world.

• Nausea and vomiting can occur at any time of the day and may be constant.¹
• The causes of nausea and vomiting in early pregnancy are unknown.
• Most women do not require treatment. However persistent vomiting and severe nausea can progress to hyperemesis gravidarum.
• Hyperemesis gravidarum refers to intractable vomiting leading to fluid and electrolyte disturbance, marked ketonuria, nutritional deficiency and weight loss.²
• Nausea in later pregnancy may be due to reflux oesophagitis and respond to antacids.

• Nausea affects about 70% and vomiting about 60% of pregnant women.
• Nausea and vomiting in pregnancy is more common in:
  • Primigravidae
  • Multiple pregnancy
  • History of previous hyperemesis
• It is less common with increasing maternal age.
• It tends to be a disease of Western society and is less common in developing countries, especially in rural communities.

• Symptoms usually start between 4 and 7 weeks gestation and resolve by 16 weeks in about 90% of women.
• Check for signs of dehydration and any possible underlying cause.
• Pre-eclampsia can cause vomiting so blood pressure may be raised.

Other causes of nausea and vomiting should be considered:

• Hydatidiform mole
• Pre-eclampsia
• Gastrointestinal cause, e.g. infection, gastritis, cholecystitis, appendicitis, obstruction, peptic ulceration, hepatitis, pancreatitis, fatty liver of pregnancy
• Urinary tract infection
• Twisted ovarian cyst
• Ear, nose and throat disease (e.g. labyrinthitis, Meniere's disease, motion sickness)
• Drug side effects
• Raised intracranial pressure
• Metabolic, e.g. diabetes, hypercalcaemia, Addison's disease, hyperparathyroidism
• Psychological (e.g. bulimia nervosa)

• Only required if there is a possible alternative diagnosis or in the assessment of the well-being of mother and fetus.
• If persistent or severe, exclude a urinary tract infection and an ultrasound scan to exclude multiple pregnancy or hydatidiform mole.
• In cases of hyperemesis: renal function and electrolytes, liver function tests, mid-stream urine and ultrasound (exclude multiple or molar pregnancy).

Most cases are mild and do not require treatment. Nausea and vomiting in pregnancy usually resolves spontaneously within 16 to 20 weeks and is not associated with a poor pregnancy outcome. However persistent vomiting and severe nausea can progress to hyperemesis if the woman is unable to maintain adequate hydration; fluid and electrolyte balance as well as nutritional status are jeopardised.³ The following interventions appear to be effective in reducing symptoms:⁴

• Non-pharmacological: ginger, P6 (wrist) acupressure
• Pharmacological: antihistamines

Management options

• Advice:
  • There is no research-based evidence on the effectiveness of dietary treatment.⁵
  • Advise to rest; eat small, frequent meals that are high in carbohydrate and low in fat.
  • Avoid any foods or smells that trigger symptoms.
• Ginger: three RCTs and one randomised crossover trial found that ginger reduced nausea and vomiting in early pregnancy. One further RCT found that ginger reduced nausea and dry retching, but had no effect on episodes of vomiting.⁵
• Drug treatment should only be given when symptoms are persistent, severe and prevent daily activities. Prochlorperazine, cyclizine and metoclopramide are often used. Due to concerns about fetal safety, there have been relatively few studies on the efficacy and safety of anti-emetics used for nausea and vomiting in pregnancy.⁶
  • Antihistamines (H₁ antagonists): two systematic reviews found limited evidence that antihistamines reduced nausea and vomiting with no evidence of teratogenicity.⁷
  • Phenothiazines: one systematic review found limited evidence that phenothiazines reduced the proportion of women with nausea and vomiting. However, the results were not conclusive. The review found no evidence of teratogenicity.⁵
  • Cyanocobalamin (vitamin B₁₂): one systematic review has found that cyanocobalamin reduces vomiting episodes compared with placebo.⁵
  • Pyridoxine (vitamin B₆): two systematic reviews found limited evidence that pyridoxine reduced nausea but found no evidence of an effect on vomiting.⁵
• Acupressure: one systematic review of small RCTs found limited evidence that P6 acupressure reduced self reported morning sickness compared with sham acupressure or no intervention. Three subsequent RCTs and two randomised crossover trials found that P6 acupressure reduced the duration, but not necessarily the intensity, of nausea and vomiting.⁵
• Acupuncture: one RCT found that acupuncture reduced nausea and retching compared with no acupuncture, with no evidence of adverse effects. However, an improvement was also found with sham acupuncture compared with no treatment. A second smaller RCT found no significant difference in nausea between acupuncture and sham acupuncture.⁵

Admission

• Women with severe symptoms should be referred for fluid, electrolyte and vitamin replacement (usually intravenously). Nutritional support (enteral or parenteral) is needed in women who have intractable symptoms and weight loss, despite appropriate therapy.
• Admit for monitoring, intravenous fluids and correction of electrolyte disturbances. if the vomiting is severe or prolonged or the woman becomes dehydrated or ketotic.

• In severe cases, dehydration, weight loss, electrolyte disturbance (e.g. ketosis) and nutritional deficiency can occur.
• Hyperemesis gravidarum is rarely associated with death, but may lead to serious complications, including Wernicke's encephalopathy, central pontine myelinolysis and spontaneous oesophageal rupture.⁸

• Most cases are self-limiting and settle without complication as pregnancy progresses.
• Nausea and vomiting of pregnancy is associated with favourable pregnancy outcomes, such as decreased risk of miscarriage and a lower incidence of perinatal death, low infant birth weight and preterm birth.⁹
• However, in severe cases (hyperemesis gravidarum) there may be an increased risk of low birth weight, congenital malformations, undescended testicles and hip dysplasia.⁹
• Infants born of women who had hyperemesis are more likely to experience decreased gestational age and increased length of hospital stay.¹⁰
• Time off work is needed by 35% of working women, who spend a mean of 62 hours away from their paid work as a result of the symptoms of nausea and vomiting.¹