A lack of data on whether drugs are safe to take during pregnancy has led to an excessive number of deaths among pregnant women, according to UK experts.

They say the lack of availabilty of hard data on the safety and effectiveness of many drugs that could be used in pregnancy had hindered the treatment of pregnant women.

This has lead to a doubling of deaths among pregnant women who have underlying health problems, it is claimed.

An editorial in the UK journal, the Drugs and Therapeutics Bulletin, says it is now time to include pregnant women in drug trials so that they can be given the drug treatment they need to treat various conditions when they are pregnant.

The article points out that because there is a lack of information on the safety or otherwise of different drugs if they are used during pregnancy, doctors are reluctant to prescribe them, and pregnant women might be concerned about taking any drug that might harm the baby.

Doctors are still concerned about a re-occurence of tragedies such as the thalidomide case in the late 1950s and early 1960s, where babies suffered deformities after their mothers took an anti-nausea medication.

The article points out that one-in-10 mothers-to-be has a condition that usualy requires medication, while four in 10 develop new conditions while they are pregnant.

The journal warns that the reluctance to prescribe to women who are pregnant can have fatal consequences.

The number of 'indirect' deaths among new mothers in the UK, where being pregnant worsens a new or pre-existing condition, has almost doubled in 20 years.

The article says while drug companies are reluctant to include pregnant women in drug trials for safety/ethical reasons, it could be equally unethical not to include them in trials of drugs that could be of benefit to them.

The editorial says those involved in drug development should look at ways to safely involve pregnant women in drug trials.