• Posted March 14, 2023

Drug Used in Pregnancies in 1960s, '70s May Be Tied to Colon Cancers Today

The children of women who took a common anti-nausea drug for pregnancy in the 1960s and 1970s may be at higher risk of colon cancer, according to a new study.

The drug, dicyclomine, is used to treat spasms caused by irritable bowel syndrome. It was also initially included in Bendectin, a drug prescribed during pregnancy starting in the 1960s to prevent nausea and vomiting.

"Our findings suggest that events in the earliest periods of life -- including the womb -- can affect risk of cancer many decades later,"said study first author Caitlin Murphy, an associate professor at University of Texas Health Science Center at Houston School of Public Health.

"As many as 25% of pregnant women received Bendectin through the mid-1970s, and there may be long-lasting consequences for offspring that continue today," Murphy said in a university news release.

Incidence rates of colon cancer are increasing among adults born in and after the 1960s, according to the study. This suggests that pregnancy-related exposures introduced at that time may now be risk factors.

To study this, researchers analyzed data from Child Health and Development Studies, a multi-generational cohort that enrolled more than 14,500 pregnant women. These women gave birth to more than 18,700 babies in Oakland, Calif., between 1959 and 1967.

About 5% of those offspring, or a total of 1,014 children, were exposed to Bendectin while in the womb.

Incidence rates of colon cancer were about three times higher in those exposed to Bendectin than those not exposed.

Researchers suspect that dicyclomine may target the developing gastrointestinal tract of the fetus. Some studies suggest infants born to women who received Bendectin during pregnancy are more likely to have gastrointestinal birth defects, Murphy said.

The manufacturer of Bendectin removed dicyclomine from the drug's formula in 1976, after reports of birth defects and concerns in the wake of the thalidomide drug tragedy. In the late 1950s and early 1960s, many pregnant women were prescribed the drug thalidomide to ease morning sickness. More than 10,000 of their babies were born with severe deformities.

The findings were published March 10 in the journal JNCI Cancer Spectrum.

Experimental studies are needed to clarify these latest findings and identify mechanisms of risk with dicyclomine, Murphy said.

More information

The U.S. Centers for Disease Control and Prevention has more on medications in pregnancy.

SOURCE: University of Texas Health Science Center at Houston, news release, March 10, 2023