Nausea and Vomiting in Pregnancy

The cause is unknown although hormonal change and genetics probably play a role. Nausea and vomiting correlates closely with the level of human chorionic gonadotropin. The psychosocial stresses of N/V in pregnancy are common and a major concern. After ruling out all the other life threatening causes of N/V including GI, GU, neurologic and metabolic disorders there are 2 varieties of nausea and vomiting in pregnancy.

1. Hyperemesis gravidarum - is a condition of severe nausea and vomiting during pregnancy leading to fluid, electrolyte and acid-base imbalance, nutritional deficiency/weight loss. It happens in approximately 0.3% of pregnancies and can lead to low birth weights. These patients may need to be admitted and should be referred to OB. Correction of fluid/electrolytes and medication for nausea should be initiated.
2. Nausea and Vomiting of pregnancy – is stressful to the mother and family but has little to no impact on the fetus. Interestingly there is an association between nausea and vomiting of pregnancy and decreased risk of miscarriage. Symptoms usually peak around 9 weeks and resolve around 20 weeks. 10% will remain symptomatic past 22 weeks.

Treatment:

• Persistent nausea and vomiting with ketones require intravenous hydration with multivitamins, including thiamine
• Avoidance of dietary triggers
• Evidence for acupressure is conflicting
• Ginger has been found in a blinded trial to reduce symptoms. Ginger may inhibit platelet function and use with anticoagulants is not advised.
• Vitamin B6 (cat A)- shows improvement in nausea scores in patients with severe nausea. Doxylamine (cat B) can be added and improves efficacy (70% reduction in N/V). The combination of these two was removed from the market in the US do to concern over congenital malformations, which was unfounded as a meta analysis of 170,000 pts showed no adverse affects to the fetus. A combination pill can still be obtained in Canada as Diclectin.
• Metoclopramide (cat B) -  reduces the number of vomiting episodes.
• Ondansetron (cat B)- may be no better than promethazine but is better tolerated.
• Promethazine (cat C) – decreases nausea and vomiting. Side effects of drowsiness and akathisia may limit its usefulness. Some small studies show increase risk of congenital hip dislocation

Niebyl JR. Clinical practice. Nausea and vomiting in pregnancy. N Engl J Med. 2010 Oct 14;363(16):1544-50.

Jarvis S, Nelson-Piercy C. Management of nausea and vomiting in pregnancy. BMJ. 2011 Jun 17;342:d3606