K. Hecht, Ph.D. and Frederick
Medical Authors and Editors, MedicineNet.com
Hypospadias is a relatively common congenital malformation (birth defect). It affects one boy in every one to two hundred born in the US. In hypospadias, the urethral opening is located along the underside of the penis, scrotum, or perineum. Hypospadias is classified in order of increasing severity as first, second, or third degree. The condition often requires surgery.
The Fear of a Birth Defect
The fear that Claritin might cause hypospadias dates to 2002. That year a Swedish study reported that the prevalence of hypospadias was twice normal among boys whose mothers had taken Claritin during pregnancy. However, insufficient data were available to determine the severity of the hypospadias, and the study did not control for confounding variables such as a family history of hypospadias.
In 2003, a small prospective study failed to confirm the association of Claritin with hypospadias. The study done in 4 countries indicated that 5 of 142 pregnancies in women exposed to Claritin resulted in infants with major malformations, a prevalence consistent with that of the general population. None had hypospadias.
New Study by the CDC
To further assess a possible association between exposure to Claritin and the occurrence of hypospadias, the CDC (Centers for Disease Control and Prevention) have analyzed data from their National Birth Defects Prevention Study. Exposure to Claritin was defined in this study as any maternal use of the drug from a month before pregnancy through the end of the first trimester (through the third month of pregnancy).
All cases of second- or third-degree hypospadias were recorded in the study. (First-degree hypospadias is so slight that it is not considered a major malformation.) In the study there 563 boys born with hypospadias. Among the 1,957 mothers of infants with hypospadias and control babies, 33 (1.7%) reported using Claritin during the exposure period.
Antihistamines in Pregnancy
During 1998 and 1999, Claritin was the drug that was most advertised directly to consumers in the US. It was used by 3% of women of childbearing age. Since late in 2002, Claritin has been available in the US without a prescription.
Because an estimated 50% of all pregnancies in the US are unintended, women frequently are exposed inadvertently to medications before learning they are pregnant.
Limitations of the Study
The CDC report is subject to at least two limitations. First, the National Birth Defects Prevention Study does not track all birth defects. Because first-degree hypospadias is excluded, the potential association between this mildest form of hypospadias and Claritin could not be assessed.
Second, women in the study were interviewed about their pregnancy exposures after delivery, and the ability to recall drug use might be different among mothers of infants with major birth defects compared with mothers of infants without major birth defects.
These results are very reassuring but they do not provide definitive information on the overall safety of Claritin. All women should continue to consult their health-care providers before using any medications during pregnancy.
Evaluation of an Association Between Loratadine and Hypospadias --- United States, 1997--2001. Morbidity and Mortality Weekly, March 19, 2004.
- Birth Defects
- Pregnancy Drug Dangers
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