A major Canadian newspaper’s investigation has found evidence that the drug Zofran may cause birth defects.

Zofran is a powerful anti-nausea drug. It is approved by the U.S. Food and Drug Administration (FDA), and the Canadian equivalent Health Canada, for use treating extreme cases of motion sickness and the violent nausea associated with chemotherapy. However, while it is not approved for morning sickness, doctors sometime use the drug for just that.

The Toronto Star had staff sift through FDA records, and found more than 20 reports of Canadian citizens who had taken Zofran during pregnancy. These reports included serious birth defects, stillbirths, and miscarriages reported among women who used Zofran. These women took Zofran to treat severe morning sickness, which is often reported during pregnancy.

So how did Zofran, a drug that could potentially cause birth defects, and is not approved for use in pregnant women, wind up causing birth defects? Under both U.S. and Canadian law, a physician may prescribe a drug for any purpose they deem fit. This is called “off-label use.”

This is practice is legal, and pragmatic. It is designed to close the gap in cases when medical research outpaces the seemingly-glacial approval process. In some cases this had gotten life-saving drugs to patients in time.

But off-label usage can also be abused. In fact, while it’s legal for a physician to prescribe drugs off-label, drug companies are strictly forbidden from promoting drugs like Zofran for any use other than their FDA-approved usage.

In some cases, it has been found that drug companies have skirted laws regarding off-label usage. While no evidence has yet come to light of this practice with respect to Zofran, major pharmaceutical companies have been caught paying physicians to promote their drugs clandestinely through back channels.

In some cases, these covert campaigns involved paying doctors to publish case studies or other research articles promoting their drugs. In other cases, doctors were paid to promote drugs in their practices, hospitals, and at medical conferences.

While this has not been alleged with Zofran, drug companies caught promoting off-label use of their drugs through cloak-and-dagger means have been fined billions by government regulators.

Zofran birth defects could echo a dark era in drug regulation in the United States. During the 1960s, an experimental drug called thalidomide was given to women to treat morning sickness.

Thalidomide was exceptional at preventing nausea, but had a serious side effect. It prevented the growth of new blood vessels. In an adult, this has no effect, and has actually led to new research into thalidomide as a cancer drug.

But in a developing fetus, particularly at the age when morning sickness is most likely, interfering with blood vessel growth sets off a change reaction that ends in serious birth defects. Disturbingly, thalidomide was available over-the-counter for years in the late 1950s and early 1960s.

Many modern rules regulating FDA approval and off-market labeling grew out of the thalidomide tragedies of the 1960s. This includes the ban on off-label promotion for drugs like Zofran.