Just a few weeks ago one million packs of birth control pills were recalled by Pfizer, a well-known drug company, and more recently seven lots of Norgestimate and Ethinyl Estradiol Tablets were recalled by Glenmark Generics Inc. In both cases, the apparent error had been in the packaging of the pills such that some placebo/sugar pills had been packaged in the area where active pills are supposed to be taken. While most women would note that there was a random mix of colors in the initial 21 days, it might be possible that someone might not question the color mix and could thus become pregnant. What would be the effect on her baby?
Despite the effectiveness of modern birth control methods, some women do become pregnant while using contraception. What are the effects of the “morning after” emergency contraceptive pills, DepoProvera, Implanon, or IUDs on an early pregnancy? The purpose of this blog is to share with you what evidence we have about prenatal exposure to various types of contraceptives.
Birth Control Pills (BCPs)
According to a study done in Denmark, about 1% of pregnant women have used BCPs during the initial part of their pregnancies. In the U.S., BCPs are still the most widely used form of reversible birth control. Thus one would expect to see some obvious, consistent patterns of infant effects. One of the largest studies, published in 1995, looked at some 65,500 women who had infants exposed to BCPs. The primary area of focus was external genital defects, as it was felt that early exposure to synthetic sex hormones (e.g., BCPs) could impact genital development. No increased risk for genital defects was found. Moreover the FDA supports the position that synthetic progesterones found in BCPs did not cause other types of non-genital birth defects.
In 2010, about 10,000 infants with 32 types of birth defects were contrasted with infants without birth defects. Of the 32 types of birth defects only two had statistical links to early pregnancy BCP use (underdeveloped left heart chamber or hole in the abdominal wall). The researchers concluded that those findings may have been by chance, not direct causation. They stated “… our findings are consistent with the majority of previous studies that found women who use OCs [oral contraceptives] during early pregnancy have no increased risk for most types of congenital malformations.”
There has also been a concern about the risk of having a Down Syndrome (Trisomy 21) baby due to prenatal BCP exposure. The weakest study found an increased risk in women under age 34—but no increased risk in women age 34 or older, when Down Syndrome babies are more common anyway. Moreover, in a study done by the U.S. Centers for Disease Control, BCP use by itself was not a significant risk factor for Trisomy 21.
Finally, in Korea 120 women who had taken BCPs at the time of conception were matched to 240 women who had not been using BCPs in early pregnancy. After all women had delivered it was determined that there were no differences in the infants’ weight or age at delivery. In the BCP-exposed group the rate of general birth defects was 3.2% compared with 3.6% in the non-exposed group.
Emergency Contraceptive Pill (ECP)
A much larger dose of hormones is used for the “morning after pill” or ECP. What happens to infants conceived when using a higher dose of hormones? In the Korean study mentioned above, there were 15 women who used high dose synthetic progesterone ECP regimens (e.g., similar to Plan B® in the U.S.). There were no adverse fetal outcomes observed. A Plan B® type of ECP has been available, over the counter, in China since 1999. Among the several hundred ECP pregnancies, a small group of 31 pregnant women were followed through delivery. There were no significant differences in incidence of miscarriage, malformations, or neonatal problems among the ECP exposed babies.
The newest ECP available in the US.. (Ella®) contains a different type of hormone. The manufacturer filed data with the FDA about pregnancies. The majority of women terminated their pregnancies; however, there were two apparently healthy live births. In another Ella® study one infant had optic nerve hypoplasia which was not judged to be related to the medication. Since Ella® was approved in the U.S. about 18 months ago there has not been an increase in reported problems for exposed infants. Usually with a newer medication there is closer scrutiny for problems.
One of the highest doses of synthetic progesterone that an infant could receive from a birth control method would be from the DepoProvera shot. A large group of children (1207 of them) exposed to Depo in utero were examined for problems with growth or attainment of puberty. The use of Depo during pregnancy did not adversely impact long term growth or sexual development of children.
Inserted under the skin, much lower doses of synthetic progesterone are released from the Implanon implant. While there have been no reports of problems with infants conceived with Implanon correctly in place, the number of pregnancies is very low. Among the prior types of implants (Norplant and Norplant II) there were no increases in ectopic pregnancies, birth defects, or infant health problems.
With respect to the older type of IUDs, a group in Italy described the outcomes of 10 IUD pregnancies. Five were terminated by abortion, two were miscarried during the first trimester, and three were delivered at term. No abnormalities were found except a major lip lesion in a newborn. Eleven women using copper IUDs had pregnancy tissue examined and it was noted that no malformations or copper deposits were present. For the Mirena, a synthetic progesterone containing IUD, no pattern of birth defects was apparent in the 35 “Mirena babies” reported to the FDA.
As you have read, pregnancies exposed to most types of hormonal birth control seem to yield healthy babies. Thus, women exposed to hormones after conception might be reassured that the chance of a healthy pregnancy, and infant, is good. Nonetheless it is important to see your GYN or family planning clinic promptly if you have a positive pregnancy test, to receive personalized counseling.
Not surprisingly, bad outcomes tend to be reported more than good. Continuing with an unplanned pregnancy is a very personal decision, but I hope that having reliable information is helpful if you find yourself pregnant despite optimal use of birth control.