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H2 Blockers Used for Heartburn Safe in Pregnant Women


Heartburn and acid reflux can be a significant problem for pregnant women, especially in the last trimester. A large collaborative cohort study has shown that H2 blocker drugs, such as Famotidine, Cimetidine and Ranitidine, pose no significant risks for the fetus even when taken in the first trimester.

Dr. Rafael Gorodischer and colleagues have published their study in the October issue of The Journal of Clinical Pharmacology. The study was a collaboration between Ben-Gurion University of the Negev, Soroka University Medical Center and Clalit Health Services -- all in Beer-Sheva, Israel -- along with the Division of Pharmacology, Hospital for Sick Children in Toronto, Canada.

The study was conducted by the three Israeli entities as part of the BeMORE collaboration (Ben-Gurion MotheRisk Obstetric Registry of Exposure). The investigation of the safety of other medications commonly used off-label in pregnancy is an ongoing project of BeMORE investigators in large cohorts of women in Southern Israel.

H2 blockers are among the most frequently recommended drugs for acid reflux symptoms of heartburn, regurgitation and trouble swallowing, which are common in pregnant women. Usually symptoms of acid reflux are more frequent and more severe in the latter months of pregnancy. It has been estimated that between 30 percent to 80 percent of pregnant women are affected.

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The study used a computerized database of medications dispensed from 1998 to 2007 to all women registered in the "Clalit" health maintenance organization, in the Southern District of Israel. This data was linked with computerized databases containing maternal and infant hospitalization records from the district hospital. The researchers also looked at maternal age, ethnic group, maternal diabetes, smoking, and peripartum fever.

A total of 117,960 infants were born during the study period. It was noted that 84,823 of the infants (72%) were born to women registered at Clalit, and 1148 (1.4%) of the latter were exposed to H2-blockers during the first trimester of pregnancy.

The rate of major congenital malformations identified in the group that was exposed to H2 blockers during the first trimester was 5.7 percent (65 of 1,148 infants), as compared with a rate of 5.3 percent (4,400 of 83,675 infants) in the unexposed group.

According to principal investigator epidemiologist Dr. Amalia Levy of the BGU Faculty of Health Sciences, and chairwoman of the BeMORE collaboration, "Exposure to H2 blockers among this group was not associated with significantly increased risks of major congenital malformations. The results were unchanged when therapeutic abortions of exposed fetuses were included in the analysis. Also, infants exposed in utero had no increased risk of perinatal mortality, low birth weight or premature birth".

Matok et al. The Safety of H2-Blockers Use During Pregnancy. The Journal of Clinical Pharmacology, 2009; DOI: 10.1177/0091270009350483
American Associates, Ben-Gurion University of the Negev News Release