Researchers are taking a look at the possibility of the morning after pill not being as effective for overweight women.

The pills are sought out to prevent unwanted pregnancy. If taken up to 72 hours after unprotected sex or after birth control fails, the pill should prevent pregnancy, according to Health Newsline.

“This is an efficacy issue. We need to find out what the association is with (body mass index) and if there is a cut-off threshold for when the medicine becomes less effective,” Monika Benstetter, an European Medicines Agency spokeswoman said.

The concerns were raised after a report in November 2013 when the pill was deemed ineffective for obese or overweight women. They have gone for a label change that will state that it is not effective for women over 176 pounds and begins to lose effectiveness for those over 165.

It has also been found that increased dosages will not aid the effectiveness in overweight women.

According to dna, the UK’s second most popular emergency contraceptive, EllaOne, will also be put under the microscope to see how effective the pill is for overweight women.

“We felt it was our ethical duty … to report those results to our health authorities here in Europe,” Erin Gainer, CEO of HRA Pharma, manufacturers of the pill, said.

The immediate advice given to women effected by these new findings is to contact a doctor and find another source of birth control.