Aug. 24, 2005 - Pregnancies that occur despite the use of emergency contraception that contains a progestin do not appear to be associated with any increased risk to mother or child, according to new research.
Although the number of women in the study was small, researchers found there was no apparent harm to the mother or developing fetus caused by using the emergency contraception -- known as the "morning after" pill -- in a failed attempt to prevent pregnancy after sexual intercourse.
Emergency contraception called Plan B consists of two 0.75-milligram doses of a progestin pill (levonorgestrel); each pill is taken 12 hours apart. A 1.5-milligram dose of levonorgestrel may also be taken in combination with an estrogen. The emergency contraception must be taken within three to five days of unprotected sex.
This form of emergency contraception is about 85% effective at preventing pregnancy and is believed to work in one of three ways: temporarily blocking eggs from being produced, preventing the formation of hormones within the ovaries that maintain a pregnancy, or keeping a fertilized egg from becoming implanted in the uterus.
A possible association between prepregnancy exposure to progestins and congenital abnormalities has been debated, they write. These abnormalities tend to arise from long-term use of levonorgestrel rather than short-term, low-dose preparations used in emergency contraception pills, they add.
Pregnancies Unaffected by Failed Emergency Contraception
In the study, which appears in the August issue of Fertility and Sterility, researchers looked at whether failed use of the morning-after pill was associated with any increased risk to the mother or fetus.
Researchers compared the number of stillbirths, birth defects, and pregnancy complications among a group of 36 pregnant women who had used the morning-after pill and a comparison group of 80 pregnant women who did not use emergency contraception. There were 25 births among the women who used the morning-after pill and 69 among the comparison group.
The results showed that babies born to women who used emergency contraception were similar in weight and length to other babies. There were no differences in the number of stillbirths, birth defects, or pregnancy complications between the two groups.
Based on these results, researchers say that unsuccessful use of the morning-after pill should not warrant a voluntary abortion due to fears of potentially adverse effects of hormonal emergency contraception.