In the 1950s, the U.S. Food and Drug Administration (FDA) approved a combination of doxylamine and pyridoxine to treat morning sickness in pregnant women. Despite the long history in the pharmaceutical marketplace, some doctors are concerned the safety and efficacy of these drugs have never properly been established.

A combination of doxylamine and pyridoxine was originally sold under the name Bendectin. By the 1970s, several studies suggested Bendectin could cause birth defects in children. Bendectin’s manufacturer stood behind the safety of its drug; but by 1983 the manufacturer voluntarily recalled it from the market.

In 2013, the FDA approved a new drug called Diclegis to treat morning sickness in pregnant women. Like Bendectin, Diclegis is a combination of doxylamine and pyridoxine. However, some doctors note serious flaws in the clinical trials that led to the original approval of a combination of doxylamine and pyridoxine to treat morning sickness.

The pivotal clinical trial leading to the drugs’ approval was never published in any scientific journal. Additionally, approximately 31% of patients enrolled in the study never completed it, meaning the data is incomplete. Several other shortcomings were discovered with the trial including the final results, which appear to be missing.

The spotty data convinced some doctors they cannot prescribe the drugs. But for women who suffer from morning sickness, there are few treatment options.

The anti-nausea medication Zofran has been widely prescribed off-label to pregnant women to treat morning sickness, but there are currently over 300 lawsuits that allege the drug causes birth defects.

Children are particularly susceptible to medications in utero because drugs can pass through the placental barrier. Despite this, very few drugs are ever properly studied in pregnant women and it appears children might be the ones paying the price.