Many antibiotics prescribed for pregnant women do not cause birth defects

According to the results of a multicenter population-based case-control study, many antibiotics used during pregnancy do not cause the development of various birth defects. The results of this study were published in the November 2009 issue of the Archives of Pediatric & Adolescent Medicine

According to experts from the United States Centers for Disease Control and Prevention (CDC), antibacterial drugs are one of the most commonly prescribed drugs during pregnancy, as the treatment of infectious diseases is essential for the health of the mother and of the fetus. Despite the fact that certain classes of antibiotics have been used for a long time and are considered relatively safe for pregnant women, no major studies have been conducted on the safety or risk of using many antibacterial drugs.

The aim of the study was to establish a relationship between the appointment of antibacterial drugs in critical periods (from 1 month before the start of pregnancy to 3 months of pregnancy) and the identification of congenital malformations.

The National Birth Defects Prevention Study is a current case-control study of the development of birth defects in the United States. The study group was made up of 13,155 women who, during pregnancy, were diagnosed with 1 of more than 30 significant malformations diagnosed as part of a congenital malformation surveillance program in 10 US states. The control group consisted of 4,941 women randomly selected from the same geographic areas.

The main impact factor studied during the study was the woman's use of antibacterial drugs for 1 month before pregnancy and during the first trimester of pregnancy. The main endpoint evaluated during the study was the odds ratio (OR), which reflects the relationship between the use of a specific antibiotic and the development of a specific birth defect, taking into account possible interference that may affect the results of the study.

During pregnancy, the number of cases of antibiotic use increased, reaching a maximum of 3 months of pregnancy. The recorded frequency of use of antibacterial drugs for the period from 3 months before pregnancy to the end of pregnancy was 29.4% in women in the study group and 29.7% in the control group.

The following malformations have been diagnosed with sulfanilamide intake: anencephaly (adjusted odds ratio (OR) 3.4, 95% confidence interval [CI], 1.3-8.8), left heart hypoplasia syndrome (Corrected OR 3.2, 95% CI 1.3-7.6), aortic coarctation (adjusted OS 2.7, 95% CI 1.3-5.6), choan's atresia (adjusted OS 8 , 0, 95% CI 2.7-23, 5), limb malformations (corrected OR 2.5, 95% CI 1.0-5.9) and diaphragmatic hernia (corrected OR 2.4, 95% CI 1 , 1 to 5.4).

When prescribing nitrofurans, the following malformations were revealed: anophthalmia or microphthalmia (corrected bone, 3.7, 95% CI 1.1-12.2), hypoplastic left heart syndrome (corrected bone 4, 2, 95% CI 1.9- 9.1), atrial septal defect (corrected OR 1.9, 95% CI 1.1-3.4), as well as the congenital split upper lip (cleft lip) and cleft palate (Corrected OR 2.1, 95% CI) 1.2-3.9). As with other antibiotics, the administration of erythromycin was accompanied by the development of 2 defects, and when prescribing penicillins, cephalosporins and fluoroquinolones, 1 defect was diagnosed.

According to the researchers, it is encouraging to note that the frequent use of penicillins, erythromycin and cephalosporins in pregnant women does not lead to the development of a large number of birth defects. However, the use of sulfonamides and nitrofurans has been accompanied by the development of a number of birth defects, which requires further study.

The limitations of this study were the retrospective design, which does not allow precise determination of the causally significant relationships and the taking into account of the possible systematic errors associated with the selection of patients. In addition, it is difficult to determine whether the development of the defect is associated with the appointment of this antibiotic or with a concomitant infection.

Researchers note the difficulty in determining the causes of birth defects. The development of each defect can contribute to several reasons. On the other hand, seemingly unrelated defects can have a common etiological factor. This study does not determine the safety of antibiotics during pregnancy, but it is encouraging that the use of many classes of antibacterial drugs does not increase the risk of birth defects.