The drug's formula consists of vitamin B6, plus the over-the-counter antihistamine doxylamine, which is found in the sleeping aid Unisom. The prescription-only Diclegis will combine both ingredients with a time-release coating designed to help women take a daily dose before nausea sets in.
Obstetricians have long recommended that nauseated pregnant women mix a similar concoction for themselves. In 2004, the American College of Obstetricians and Gynecologists issued guidelines for the combination it called a first-line therapy.
Ashton said the drug had not been studied in treatment of Hyperemesis gravidarum, the severe form of morning sickness that put Kate Middleton in the hospital early in her pregnancy.
Ashton also recommended trying lifestyle changes, such as eating small, frequent bland snacks, acupressure wrist bands and meditation before taking medication to ease morning sickness. But if symptoms become overwhelming, Ashton said Diclegis could be a good option.
"Vomiting a few times a day may be something a pregnant woman can handle for a short period of time," she said. "Vomiting hourly is not."