On average, 6-8% of pregnant women have hypertension, or high blood pressure. Nearly 5% 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.

Harvard researchers studied the database of more than 1 million Medicaid patients. Nearly 50,000 filled prescriptions for high-blood pressure drugs during their pregnancies.

While the two drugs Methyldopa and Labetalol are the generally preferred anti-hypertensive medications for use during pregnancy, others were also prescribed. These included drugs that are found to cause harmful side effects, especially during the second and third trimesters.

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