Clinical Evidence Concise: A Publication of the BMJ Publishing Group
Nausea and Vomiting in Early Pregnancy
Am Fam Physician. 2003 Jul 1;68(1):143-144.
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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.
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.
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).
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.
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?
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.
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.
One systematic review has found insufficient evidence to assess the effects of ginger in hyperemesis gravidarum.
We found insufficient evidence to assess the effects of ondansetron in hyperemesis gravidarum.
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.
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
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
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
search date:October 2002
Adapted with permission from Jewell D. Nausea and vomiting in early pregnancy. Clin Evid Concise 2003;9:293–4.
1. Medalie JH. Relationship between nausea and/or vomiting in early pregnancy and abortion. Lancet. 1957;2:117–9.
2. Whitehead SA, Andrews PL, Chamberlain GV. Characterization of nausea and vomiting in early pregnancy: a survey of 1000 women. J Obstet Gynaecol. 1992;12:364–9.
3. Gadsby R, Barnie-Adshead AM, Jagger C. A prospective study of nausea and vomiting during pregnancy. Br J Gen Pract. 1993;43:245–8.
4. Baron TH, Ramirez B, Richter JE. Gastrointestinal motility disorders during pregnancy. Ann Intern Med. 1993;118:366–75.
5. Weigel MM, Weigel RM. Nausea and vomiting of early pregnancy and pregnancy outcome. A meta-analytical review. Br J Obst Gynaecol. 1989;96:1312–8.
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