The nausea of morning sickness can strike at any time of day. For some women, it can be particularly bad, such as for Duchess Catherine of Cambridge, the wife of Prince William.
Her morning sickness was a very severe kind called hyperemesis gravidarum (HG). It can can cause dehydration bad enough to send those women suffering from it to the hospital.
About 2 percent of all pregnant women will experience HG. In addition, about 75 to 85 percent of women who had HG during their first pregnancy will have it in their next one.
But a recent small, unpublished study may offer a way for these women to reduce their risk of having it again. Taking a medication called Diclectin at the start of pregnancy may help women avoid severe morning sickness or HG if they have had it in the past.
About twice as many women in this study who took Diclectin at the start of their pregnancy did not experience HG, compared to those who only took Diclectin when they started feeling nauseous.
The study, led by Gideon Koren, MD, of The Hospital for Sick Children in Toronto, ran a trial to see whether it was possible to lower the incidence of HG among women who have already had it by giving them medication at the start of their pregnancies.
The study included 59 women who had experienced severe nausea and vomiting or had been diagnosed with HG in a previous pregnancy.
Half the women were given a medication called Diclectin as soon as they found out they were pregnant. The other 29 women were only given Diclectin at the first sign of nausea.
Diclectin contains 10 mg of vitamin B6 (pyridoxine) and 10 mg of doxylamine, an antihistamine. Diclectin is the Canadian brand name for the medication.
The US brand name was Bendectin until it was voluntarily removed from use in 1983 because of concerns about possible birth defects. Studies have since shown that it does not cause birth defects.
Diclectin is classified as a Risk Factor A drug in Canada, a designation which is equivalent to a Category A drug at the FDA. This classification means it is in the safest category to take during pregnancy.
During this study, researchers interviewed the women through phone calls an average of eight times during the women's pregnancies to find out their symptoms.
Among the women who took the Diclectin right away, 43.3 percent did not experience HG. Among those who did not take it until they felt nauseous, only 20.6 percent avoided HG.
In addition, only 15.4 percent of the women who took Diclectin right away experienced moderately severe cases of nausea and vomiting during the first three weeks of the study. Among those who waited, 39.1 percent experienced moderately severe morning sickness.
Among the women who began taking Diclectin right away, 78 percent stopped having nausea and vomiting before delivery, compared to 50 percent among those who waited to take the medication.
The researchers concluded that taken Diclectin pre-emptively appeared to reduce the amount of severe morning sickness or HG that women experience.
Jen Mushtaler, MD, an obstetrician in Austin, Texas, and a dailyRx expert, said her patients sometimes take the two active ingredients in Diclectin/Bendectin on their own to address morning sickness symptoms.
"The data has been very reassuring in terms of safety," Dr. Mushtaler said about Diclectin/Bendectin. "Many of my patients get relief from the combination of vitamin B complex and half a Unisom, whose active ingredient is doxylamine."
Despite the findings, this study has not yet been published in a peer-reviewed journal, so its results should be regarded as preliminary and still require review by researchers in the field. It is also a very small study with results that should be confirmed with larger studies.
The most common side effect of Diclectin is drowsiness. Other possible side effects include diarrhea, difficulty sleeping, dizziness, headache, irritability or nervousness.
Very rare but possible serious side effects that have been reported include seizures, pounding heartbeat, stomach pain and difficulty urinating.
The study was presented February 14 at the Society for Maternal-Fetal Medicine's annual meeting, The Pregnancy Meeting, in San Francisco. Information was unavailable regarding funding and conflicts of interest.