The study was small -- only 24 women -- and looked only at one brand of ginkgo. But five of the women showed high levels of a toxin called colchicine. Colchicine disrupts proper cell division and can be fatal in high doses. The five women with high levels of colchicine all took the same brand of ginkgo.
The researchers say they can't assume that all brands of the herb could cause this problem, but they caution that these supplements should be avoided during pregnancy. And others agree.
"To use over-the-counter herbals during pregnancy is crazy," says Dr. Ann Walker, a registered medical herbalist and a senior lecturer in human nutrition at the University of Reading in the United Kingdom. "The rule is that women should never take anything during pregnancy unless it is absolutely necessary." And, she says, ginkgo supplements are definitely not necessary during pregnancy.
To learn more about avoiding birth defects, read this article from the U.S. Centers for Disease Control and Prevention.