On average six to eight percent of pregnant women have hypertension or high blood pressure.

Nearly 5 percent of those pregnant women are prescribed drugs to treat it, including some that aren't considered safe for soon-to-be moms or their babies.

These are the findings of a new study in the Journal of Hypertension, a publication of the American Heart Association.

Harvard researchers studied the database of more than 1 million Medicaid patients. Nearly 50-thousand filled prescriptions for high blood pressure drugs during their pregnancies.

While two drugs, methyldopa and labetalol, are the generally preferred anti-hypertensives for use during pregnancy, others were also prescribed. These included ACE inhibitors and angiotensin receptor blockers, which have been found to cause harmful side effects especially during the second and third trimesters.

With that, the researchers say it's urgent to further study the safest way to treat hypertensive moms-to-be.

I'm Dr. Cindy Haines of HealthDay TV, with the news the doctors are reading, health news that matters to you.