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Alcohol and Substance

Preventing recurrence of severe morning sickness

Gideon Koren, MD, FRCPC, Caroline Maltepe

December 2006



A recent Motherisk article showed that initiating antinauseants even before symptoms start could prevent recurrence of severe morning sickness. In the study described, however, different physicians used different drugs. How can one be sure which drugs work?


The study of26 women who had had severe morning sickness during previous pregnancies showed that using antiemetics before symptoms of morning sickness started appeared to prevent recurrence of severe morning sickness in subsequent pregnancies. Physicians in the United States used various antinauseant drugs. Physicians in Canada administered only one drug, the combination of doxylamine-pyridoxine (Diclectin®), to 12 women. Subanalysis of these 12 women revealed that pre-emptive use of doxylamine-pyridoxine significantly decreased the likelihood that severe morning sickness would recur.


Dans un récent article de Motherisk, on faisait valoir que l’amorce d’une thérapie aux médicaments antinauséeux avant même l’apparition des symptômes pourrait prévenir la récurrence de nausées matinales sévères. Par contre, dans l’étude décrite, divers médecins utilisaient différents médicaments. Comment peut-on savoir quel médicament fonctionne?


L’étude auprès de 26 femmes qui avaient souffert de nausées matinales sérieuses au cours de grossesses antérieures a démontré que le recours aux antiémétiques avant l’apparition des symptômes de nausées matinales semblait prévenir la survenance de nausées matinales sévères dans les grossesses subséquentes. Les médecins aux États-Unis avaient utilisé différents médicaments antinauséeux. Les médecins au Canada avaient administré un seul et même médicament, la combinaison de doxylamine et de pyridoxine (Diclectin®) chez 12 femmes. Une sous-analyse réalisée chez ces 12 femmes a révélé que l’utilisation par anticipation de la doxylamine-pyridoxine réduisait considérablement la probabilité d’une réapparition des nausées matinales sévères.

We have recently documented that women who have experienced severe nausea and vomiting during previous pregnancies benefit from pre-emptive antinauseant treatment during their current pregnancies.1 Treatment needs to be started before symptoms appear.

Among the 26 women participating in the study,1 14 were American patients who received various combinations of antihistamines or ondansetron as their physicians preferred. The other 12 women were Canadian and were treated with 10 mg of pyridoxine combined with 10 mg of doxylamine (Diclectin®, a delayed-release product). All these 12 women had experienced severe nausea and vomiting during their previous pregnancies. Pre-emptive therapy decreased the severity of their symptoms significantly during their current pregnancies to mild in 5 cases and moderate in 4 cases (P < .01). In 3 cases, severity remained the same. In their previous pregnancies, 8 of these women had had to be hospitalized for severe nausea and vomiting. In their current pregnancies, only 1 woman had to be hospitalized (P < .01).

Among 12 matched controls who had had severe nausea and vomiting during previous pregnancies and who did not receive pre-emptive antinauseant therapy, only 1 woman had less severe symptoms during her current pregnancy. Her nausea and vomiting improved from severe to moderate.

The apparent effect of doxylamine-pyridoxine was stronger than the effects of any other antiemetics with which the American women were treated. Results suggest that pre-emptive antiemetic treatment can modify the vicious circle of severe nausea and vomiting during pregnancy that causes many women to need hospitalization.

Motherisk is currently conducting a randomized controlled trial comparing pre-emptive doxylamine-pyridoxine therapy with the regular recommended protocol (ie, starting medication only in response to symptoms) to corroborate the initial findings of our prospective observational study. Study patients are women who are planning pregnancy or who have just conceived who experienced severe nausea and vomiting during their previous pregnancies.

Competing interests

Duchesnay, manufacturer of Diclectin®, partly sponsors the Motherisk NVP Healthline.


1. Koren G, Maltepe C. Pre-emptive therapy for severe nausea and vomiting of pregnancy and hyperemesis gravidarum. J Obstet Gynecol 2004;24:530-3.

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