From the Guidelines
For pregnant women experiencing nausea and vomiting, the recommended first-line antiemetic options include vitamin B6 (pyridoxine) 10-25mg three times daily, which can be combined with doxylamine 12.5mg, as well as ginger supplements (250mg four times daily). These options are considered safe and effective based on recent evidence 1. If these are insufficient, second-line medications include promethazine 12.5-25mg orally or rectally every 4-6 hours, or metoclopramide 10mg orally three times daily, as supported by studies 1. Some key points to consider when selecting an antiemetic for pregnant women include:
- The safety profile of the medication, with doxylamine and pyridoxine being well-established as safe options 1
- The potential risks associated with certain medications, such as ondansetron, which may have a small increased risk of oral clefts if used in the first trimester 1
- The importance of starting with the safest options and escalating as needed to minimize potential risks to the developing fetus
- The use of glucocorticosteroids, which have been shown to cause an increase in oral clefts incidence when used before 10 weeks of gestation, and should be replaced by steroids that are metabolized in the placenta 1
- The lack of human data regarding the safety of neurokinin-1 (NK-1) antagonists during pregnancy, and the potential risks associated with second-generation antipsychotics like olanzapine 1
From the FDA Drug Label
8.1 Pregnancy Risk Summary Published epidemiological studies on the association between ondansetron use and major birth defects have reported inconsistent findings and have important methodological limitations that preclude conclusions about the safety of ondansetron use in pregnancy The FDA drug label does not answer the question.
From the Research
Antiemetics Recommended in Pregnancy
The following antiemetics are recommended for use in pregnancy:
- Ginger 2, 3
- Vitamin B6 (pyridoxine) 2, 3, 4, 5, 6
- Antihistamines 2, 3
- Metoclopramide (for mild symptoms) 2, 3
- Pyridoxine-doxylamine (Diclectin) 2, 3, 5
- Ondansetron (for moderate symptoms) 2, 3
- Promethazine 3
- Corticosteroids (for severe cases) 2, 3
Dosage and Administration
The recommended dosage and administration of these antiemetics vary:
- Vitamin B6: 10mg four times a day, alone or in combination with doxylamine 4
- Pyridoxine-doxylamine (Diclectin): slow release tablet, 10mg pyridoxine and 10mg doxylamine 3, 5
Efficacy and Safety
These antiemetics have been shown to be effective in reducing symptoms of nausea and vomiting in pregnancy:
- Ginger, antihistamines, metoclopramide, and vitamin B6 were associated with improved symptoms compared to placebo 2
- Pyridoxine-doxylamine and ondansetron were associated with greater benefit than placebo for moderate symptoms 2, 3
- Corticosteroids may be associated with benefit in severe cases 2, 3
- Vitamin B6 supplementation alone or in combination with other active substances significantly improved symptoms of nausea 6