Image copyright Roger Mathew Smith Image caption Merck’s animal tests found its new contraceptive is likely to cause birth defects
A contraceptive pill the size of a sugar cube could cause birth defects in foetuses, even in a mother of up to four children, a US review has found.
Pregnant women who take the new drug, Cordyla, should stop immediately because the findings suggest it may be harmful to their health, the researchers said.
Researchers were investigating the safety of the “pharmaceutical behemoth”, according to the paper.
They said the findings should not be used as “a cautionary principle”.
The gel is a replacement form of the chemical contraceptive Gemzar, which has been available for women of reproductive age for more than 20 years.
Health chiefs already advise pregnant women taking the long-term contraceptive to stop taking it at 12 weeks and not start again until 20 weeks.
But the latest study of the Pill’s long-term effect on foetuses, published by the New England Journal of Medicine, suggests the discontinuation of its use should be removed altogether, because the GlaxoSmithKline drug may cause problems.
Researchers from the University of North Carolina at Chapel Hill and the University of Virginia concluded the new pill raises a “significant risk” for birth defects in offspring.
Those defects include brittle bones, cleft palates, low birth weight and hearing loss.
Experts agreed that the findings should not be used as a “cautionary principle”.
However, they added that women taking the pill who are pregnant may need to be informed about them, as they can have unintended consequences on the health of their children.
Scientists have known that some birth defects occur after women taking the Pill stop taking it for a few months.
However, Cordyla does not stop once the pill has been discontinued. It is administered every three months.
Cordyla works by blocking estrogen and progesterone receptors in the ovarian gland.
Researchers had previously found that in mice babies exposed to the gel at early pregnancy appeared to have lower muscle strength.
However, the adverse effects of the contraceptive gel were only found in research carried out on lab mice and monkeys – and not in humans.
How does the Pill work?
A pill is a product in which three chemicals are added to the urine of a woman. This blocks the hormone estrogen, preventing sperm from fertilising the egg.
What’s the history of hormonal birth control?
In the 1960s, hormone-based birth control methods were popular
In the 1970s the pill became a mainstay for women trying to avoid getting pregnant.
However, it’s no longer safe for pregnant women because women have learned how to trick them. Around half of all mums in Britain take some form of hormonal contraception.
How are the various types of pills tested?
There are chemical alternatives that have been developed that work in much the same way as the original birth control pills, but no-one has yet developed a fully natural alternative.
What else is being looked at?
The researchers pointed out that the chemical used in Cordyla, triamcinolone bromide, is currently banned because it is linked to heart and brain problems in animals. But since it has only been clinically tested for contraception, the findings have not been peer-reviewed.