What are the effects of treatments for nausea and vomiting in early pregnancy?

LIKELY TO BE BENEFICIAL

Antihistamines (H1 antagonists)

Systematic reviews have found limited evidence that antihistamines reduce the number of women suffering nausea and vomiting, but with no evidence of teratogenicity.

Cyanocobalamin (vitamin B12)

One systematic review has found that cyanocobalamin significantly reduces vomiting episodes compared with placebo.

Ginger

One randomized controlled trial (RCT) found that ginger reduced nausea and vomiting in early pregnancy.

Pyridoxine (vitamin B6)

Systematic reviews have found limited evidence that pyridoxine reduces nausea score, but no evidence on the effect on vomiting.

UNKNOWN EFFECTIVENESS

Acupuncture

One RCT found limited evidence that acupuncture improved nausea scores, retching, and well-being compared with no acupuncture, without increasing adverse effects. A significant improvement was found with traditional acupuncture, PC6 acupuncture, and sham acupuncture compared with no treatment after three weeks.

Dietary interventions (excluding ginger)

We found insufficient evidence to assess the effects of dietary interventions (excluding ginger).

P6 acupressure

One systematic review including small RCTs found limited evidence that P6 acupressure significantly reduces self-reported morning sickness. One subsequent RCT found that P6 acupressure reduced duration, but not intensity, of nausea and vomiting.

Phenothiazines

One systematic review found limited evidence that phenothiazines reduce the number of women with nausea and vomiting.

What are the effects of treatments for hyperemesis gravidarum?

UNKNOWN EFFECTIVENESS

Corticosteroids

Systematic reviews have found insufficient evidence to assess the effects of methylprednisolone in hyperemesis. One RCT found insufficient evidence on the effects of oral prednisolone.

Diazepam

One systematic review has found insufficient evidence on the effects of diazepam in pregnancy.

Dietary interventions (excluding ginger)

We found insufficient evidence to assess the effects of dietary interventions.

Ginger

One systematic review has found insufficient evidence to assess the effects of ginger in hyperemesis gravidarum.

Ondansetron

We found insufficient evidence to assess the effects of ondansetron in hyperemesis gravidarum.

Definition

The severity of nausea and vomiting in early pregnancy varies greatly among women. Hyperemesis gravidarum is persistent vomiting that is severe enough to cause fluid and electrolyte disturbance. It usually requires hospital admission.

Incidence/Prevalence

Nausea and vomiting are the most common symptoms experienced in the first trimester of pregnancy, affecting 70 to 85 percent of women.^1–3 Only 17 percent of women report that nausea and vomiting are confined to the morning, and 13 percent are affected beyond 20 weeks' gestation. Hyperemesis is much less common, with an incidence of 3.5 per 1,000 deliveries.⁴

Etiology/Risk Factors

The causes of nausea and vomiting in pregnancy are unknown. One theory, that they are caused by the rise in human chorionic gonadotropin concentration, is compatible with the natural history of the condition, its severity in pregnancies affected by hydatidiform mole and its good prognosis (see below).⁴ The etiology of hyperemesis gravidarum is also uncertain. Again, endocrine and psychologic factors are suspected, but evidence is inconclusive.⁴

Prognosis

One systematic review (search date 1998, 11 studies) found that nausea and vomiting were associated with a reduced risk of miscarriage (6 studies; 14,564 women; odds ratio: 0.36; 95 percent confidence interval: 0.32 to 0.42), but found no relationship with perinatal mortality.⁵ Nausea and vomiting and hyperemesis usually improve over the course of pregnancy, but one study found that 13 percent of women reported nausea and vomiting to persist beyond 20 weeks' gestation.²