A prospective controlled multicentre study of clarithromycin in pregnancy

Clarithromycin is a relatively new macrolide antibiotic with an action spec trum similar to that of erythromycin. Its main indications for use are for upper and lower respiratory and skin and soft tissue infections. Little is known about its safety in pregnancy, although animal reproductive studies f ound an increased rate of cardiovascular anomalies, cleft palate, and embry onic loss. Human data, limited to case reports and one small uncontrolled s tudy, cannot allow evidence based counseling of pregnant women who were exp osed to the drug before finding out they were pregnant. Pregnant women who had been counseled on the use of clarithromycin by five centers, were match ed for age, smoking, and alcohol use with a control group of pregnant women who were exposed to nonteratogenic antibiotics. A total of 157 women were followed up. Of these, 122 were exposed to the drug in the first trimester. There were no significant differences found between the two groups in the rates of major and minor malformations; 2.3 versus 1.4% for major (p = 0.86 ) and 5.4 versus 4.9% for minor (p = 0.96). Spontaneous abortion rates in t he exposed group was significantly different, higher (14%) than in the cont rol group (7%) (p = 0.04). This first prospective controlled study of expos ure to clarithromycin in pregnancy suggests that this agent does not increa se the rate of major malformations above the baseline risk of 1-3%, The hig her rate of reported spontaneous abortions, although still within the expec ted baseline rate, may warrant further study.