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Can Birth Control Pills Cause a Miscarriage?

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Updated June 06, 2014

Question: Can Birth Control Pills Cause a Miscarriage?

The answer to the question of whether birth control pills or other hormonal contraception can cause a miscarriage depends on what you mean by the question.

Answer:

In general, birth control pills probably do not increase risk of miscarriage, even in women who accidentally get pregnant while still on the pill.

Birth Control and Risk of Future Miscarriage

One 2005 study did find that using oral contraceptives for longer than two years led to an increased risk of miscarriage, but other researchers have theorized the opposite. A 1995 study found that using hormonal birth control for a long time could preserve the eggs and decrease the risk of miscarriage due to chromosomal abnormalities for moms over 30. Another study in 2002 found that long-term use of oral contraception led to moms getting pregnant more quickly after deciding to conceive, and the researchers cited additional past research that suggested pregnancies after recent pill usage were less likely to end in miscarriage.

So, currently the evidence is conflicting on this point, but there seems to be more evidence that exposure to hormonal birth control pills does not increase risk of miscarriage than evidence that it does.

Risk of Miscarriage for a Pregnancy Conceived While on the Pill

When used appropriately, most types of birth control pills are considered more than 99% effective at preventing pregnancy. Yet, sometimes women get pregnant while taking the pill -- such as if they frequently forget to take the pill or if they are using medications that decrease the effectiveness of the pill.

If you are in this situation and plan to keep your baby, you should stop taking the pill immediately -- but there shouldn't be an increased risk of miscarriage or any other problems with the pregnancy due to the accidental exposure. A large 2008 study examined a registry of 92,719 women and found no evidence of increased risk of fetal death in babies exposed to artificial hormones during pregnancy.

Using the Pill to End a Pregnancy

Finally, if you are facing an unwanted pregnancy, you might be wondering about the Internet stories about taking large doses of birth control pills to end the pregnancy. But if you have already confirmed you're pregnant, this strategy is not going to do anything for you and is not likely to end your pregnancy. You will need to research other options for unwanted pregnancy.

Technically, it is true that taking a large amount of birth control pills could work for emergency contraception if this is done within a few days after intercourse, but by the time a pregnancy test comes back positive, a large dose of birth control hormones will probably not terminate the pregnancy. If you are considering a large pill dose as emergency contraception within a few days after unprotected intercourse, however, be sure to talk to a physician or pharmacist first because the necessary dosage to use standard birth control pills as emergency contraception varies by brand of pill.

Sources:

Farrow, Alexandra, M.G.R. Hull, K. Northstone, H. Taylor, W.C.L. Ford, and Jean Golding, "Prolonged use of oral contraception before a planned pregnancy is associated with a decreased risk of delayed conception." Human Reproduction 2002. Accessed 14 Aug 2008.

Ford, Judith Helen and Lesley MacCormac, "Pregnancy and lifestyle study: the long-term use of the contraceptive pill and the risk of age-related miscarriage." Human Reproduction 1995. Accessed 14 Aug 2008.

García-Enguídanos, A., D. Martínez, M. Calle, S. Luna, J. Valero de Bernabé, V. Domínguez-Rojas, "Long-term use of oral contraceptives increases the risk of miscarriage." Fertility and Sterility 2003. Accessed 14 Aug 2008.

Jellesen, Rikke, Katrine Strandberg-Larsen, Tina Jørgensen, Jørn Olsen, Ane M. Thulstrup and Anne-Marie N. Andersen, "Maternal use of oral contraceptives and risk of fetal death." Paediatric and Perinatal Epidemiology Jun 2008. Accessed 15 Aug 2008.

Office of Population Research & Association of Reproductive Health Professionals, "Which birth control pills can be used for emergency contraception in the United States?" The Emergency Contraception Website. Jul 2008. Accessed 14 Aug 2008.

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