ACOG Guidelines at a Glance: Nausea and Vomiting of Pregnancy
Maternal and fetal effects
While death due to hyperemesis is rare, morbidity can be significant if the condition is not properly managed, not to mention the psychological impact that prompts some women to consider termination of pregnancy. Wernicke encephalopathy is caused by vitamin B1 deficiency as a result of persistent vomiting leading to nutrition deprivation and has resulted in permanent neurological disability and death. As such, it is important that treatment, particularly on admission, include hydration and replacement of the B vitamin, thiamine and attention to electrolyte balance. When replacing fluid care to be taken in overcorrection of severe and prolonged hyponatremia (< 120 meg/L) which could lead to osmotic demyelination syndrome.
A systematic review and meta-analysis of women with hyperemesis gravidarum showed a higher incidence of low birthweight and small for gestational age infants at birth, and premature infants.4 Otherwise, a lower rate of first-trimester pregnancy loss has been reported in women with nausea and vomiting and no increased risk of birth defects.
Recommendations for management
Treatment of nausea and vomiting depends on the perception of severity. Basic recommendations include avoidance of stimuli that provoke nausea and vomiting such as sensory stimuli to strong odors, and other sensory stimuli such as heat and noises that trigger the labyrinthine areas. Dietary counseling about frequent small meals and avoidance of spicy or fatty foods is appropriate even though the evidence for such recommendation is lacking.
Ginger has been recommended and shown, in some randomized trials, to improve symptoms for some women.5 Studies of other treatments such as acupressure, acupuncture, or electrical nerve stimulation at the P6 point on the inside of the wrist have produced conflicting results on benefit. A systematic review of randomized trials found no difference for P6 acupuncture and acupressure wristbands compared to placebo.2
For many decades pyridoxine (vitamin B6) has been the primary recommendation for pharmacotherapy for nausea and vomiting of pregnancy. Doxylamine (10 mg) and vitamin B6 (10 mg) was available for use in the United States from 1958 to 1983 as Bendectin until removed from the market. Many clinicians continued to prescribe vitamin B6 and doxylamine as first line as an over-the-counter regimen for nausea and vomiting. In 2013 the US Food and Drug Administration has approved the release of a new product containing doxylamine-vitamin B6, marketed as Diclectin, which was proven effective in significantly improving nausea and vomiting symptoms compared to placebo.6 The medication should be prescribed before bedtime as a prophylaxis against “morning sickness.”
Various phenothiazines have been prescribed and are effective as treatment for more significant nausea and vomiting. Over the last decade drugs that reduce chemotherapy-induced emesis (the 5-hydroxytryptamine 3 inhibitor, ondansetron, and metoclopramide) have gained favor as a treatment for women with hyperemesis. In various trials both have been found to have similar efficacy when given orally, subcutaneously and intravenously (IV). Continuous subcutaneous pump therapy, while not widely used, has limited evidence of efficacy beyond oral therapy and it is associated with complications in 25% to 31% of patients.7 While there have been reports of an association between ondansetron use in early pregnancy and birth defects of the heart and oral clefts, a prospective cohort and a retrospective cohort study showed no increased risk of congenital anomalies over the background risk for such congenital defects.8
For hyperemesis resistant to traditional antiemetic regimens, corticosteroids have been studied in randomized trials to reduce readmission with IV dosing followed by oral tapering.9 Patients who do not respond in 3 days are not likely to respond. Treatment with methylprednisolone should be reserved for refractory cases of hyperemesis as a last-resort treatment.