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THURSDAY, March 18 (HealthDayNews) -- Contrary to previous belief, there appears to be no association between the widely used allergy drug Claritin and a male birth defect called hypospadias.

Although the published report, appearing in the March 19 issue of the Morbidity and Mortality Weekly Report, only covers the period from a month before conception to the end of the first trimester, the researchers actually have reassuring data over an extended period.

"We do have information for each and every month," says study co-author Jennita Reefhuis, an epidemiologist with the National Center on Birth Defects and Developmental Disabilities, part of the U.S. Centers for Disease Control and Prevention in Atlanta. "We did look at different time periods, more narrow time periods, as well as the entire pregnancy, and it didn't change the results."

The researchers also stress this does mean the drug is safe for pregnant women in all respects.

Hypospadias is a condition in which the urethral opening is not at the tip of the penis, but elsewhere along the underside of the penis or scrotum. The defect is classified as first-, second- or third-degree, depending on how far afield the actual opening is from where it should be. Hypospadias can usually be corrected by surgery.

According to the report, during 1998-99, loratadine (Claritin) was the drug most commonly advertised directly to consumers and was used by 3 percent of women of reproductive age.

The U.S. Food and Drug Administration approved the drug for over-the-counter sales in November of 2002. Because roughly half of all pregnancies in the United States are unintended, women frequently are exposed inadvertently to medications before they know they are pregnant.

Alarm bells rang in 2002, when a Swedish study found women who had taken loratadine while pregnant had twice the prevalence of boys born with hypospadias than in the general population.

That study, however, did not control for factors such as family history or age of the mother. Moreover, a year later, another study found that women taking loratadine while pregnant had no higher rate of babies born with hypospadias.

In this latest report, the researchers analyzed data from the National Birth Defects Prevention Study (NBDPS). In all, the data included 563 male infants with hypospadias and 1,444 controls, all born between Oct. 1, 1997, and June 30, 2001.

There turned out to be no association between the prevalence of the condition and whether the mother had taken loratadine.

Although Reefhuis is confident loratadine does not contribute to hypospadias, she emphasizes "this does not mean that loratadine is safe throughout pregnancy for all women."

Because of the risks of different medications (some of them as yet known), she adds, "We feel very strongly that women, if they re pregnant, should talk to their physician before they start taking medication. . . It's also important for women who do have serious illnesses that they don't stop taking medications when they should."

"While the association between taking this drug and this particular form of birth defect is not strong, pregnant women need information about what's safe and not safe," says Dr. Nancy S. Green, medical director of the March of Dimes in White Plains, N.Y. "This is like the tip of the iceberg in terms of safety data for all medications."

Meanwhile, Schering-Plough Corp., which makes Claritin, hailed the findings.

"Certainly this assessment confirms the favorable risk-benefit ratio of loratadine," says company spokeswoman Julie Lux. "Patients can continue to use Claritin with confidence and, according to the labeling, pregnant women should always talk to a health-care professional before using any medication."

More information

The U.S. Centers for Disease Control and Prevention has more information on having a healthy pregnancy. The March of Dimes has more on genital and urinary tract defects.

(SOURCES: Jennita Reefhuis, Ph.D., epidemiologist, National Center on Birth Defects and Developmental Disabilities, U.S. Centers for Disease Control and Prevention, Atlanta; Nancy S. Green, M.D., medical director, March of Dimes, White Plains, N.Y.; Julie Lux, spokeswoman, Schering-Plough Corp., Kenilworth, N.J.; March 19, 2004, Morbidity and Mortality Weekly Report)

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