Women who keep taking oral contraceptives around the time of conception and early pregnancy should not worry about birth defects, according to researchers. The study, published in the journal The BMJ, found no link between birth defects and oral contraceptives, contrary to popular belief.

“Women who become pregnant either soon after stopping oral contraceptives, or even while taking them, should know that this exposure is unlikely to cause their fetus to develop a birth defect,” first author Brittany Charlton, a researcher in the Harvard Chan School Department of Epidemiology and an instructor at Harvard Medical School and Boston Children’s Hospital, said in a press release. “This should reassure women as well as their health care providers.”

Experts claim that oral contraceptives are 99 percent effective with proper use; however, almost 10 percent of women still become pregnant within the first year of using them. Until now, not much was known about the potential health effects of the exposure to the hormones in oral contraceptives on children in utero, the researchers added.

The team studied 880,694 births in Denmark and checked the health of the newborns during a follow-up a year later. They estimated oral contraceptive use based on the date of the mother’s latest filled prescription.

One-fifth of the women reported never using oral contraceptives before becoming pregnant, and more than two-thirds had stopped using oral contraceptives at least three months before becoming pregnant. Additionally, 8 percent had stopped the use within three months of pregnancy and only 1 percent used contraceptives after becoming pregnant.

The researchers found no increased risk of giving birth to a child with a birth defect compared with women who never took the medication or stopped them before becoming pregnant. The risk of birth defects like limb problems, cleft lips or palates, spina bifida or heart defects was consistent regardless of exposure to oral contraceptives -- about 25 birth defects per 1,000 births.

The results were the same even if other factors such as stillbirths and induced abortions have been taken into account. Charlton concluded that these results will provide relief to health care providers and women who accidently took contraceptives, not realising they were pregnant.