What happens if you get pregnant while on birth control

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WEDNESDAY, Jan. 6, 2016 (HealthDay News) -- Becoming pregnant while taking birth control pills doesn't seem to increase the risk of birth defects, a new study suggests.

Researchers found similar rates of birth defects -- about 25 infants out of 1,000 -- among women who never used birth control pills and those who took them before pregnancy or took them before realizing they were pregnant.

"Women who become pregnant either soon after stopping oral contraceptives, or even while taking them, should know that this exposure is unlikely to cause the fetus to develop a birth defect," said lead researcher Brittany Charlton.

"This should reassure women as well as their doctors," said Charlton, an instructor in the department of epidemiology at Harvard's T.H. Chan School of Public Health in Boston.

However, she cautioned that this study can't prove that birth control pills don't cause birth defects, only that there appears to be no link.

Dr. Jennifer Wu, an obstetrician and gynecologist at Lenox Hill Hospital in New York City, said the study findings aren't surprising.

"It's something we have known for a while," she said. Still, "many women in the United States are on birth control pills, so it's reassuring to know that they don't cause any birth defects, and women don't have to worry about it during pregnancy."

Although oral contraceptives are highly effective at preventing pregnancy, about 9 percent of women get pregnant the first year of using them. Usually this is because they missed a dose or used other medications -- including anti-seizure drugs, antibiotics, antidepressants or some HIV drugs -- that can make the contraceptive less effective, Charlton said.

In many other cases, women stop taking "the pill" when they want to conceive and become pregnant within a few months.

Whether the hormones in birth control pills could affect fetal development when used around the time of conception hasn't been well-studied, the study authors explained in background notes.

For the study, the researchers used national medical registries to collect data from Denmark from 1997 to 2011 on all live births, birth defects and mothers' medical conditions.

Among more than 880,000 births, 2.5 percent of the babies had a birth defect such as a cleft palate or an arm or leg defect, the researchers found.

Specifically, Charlton's team found that for every 1,000 births, 25.1 infants of mothers who never used the pill had birth defects, as did 25.0 of infants of mothers who had used birth control pills more than three months before pregnancy. The rate was 24.9 among mothers who used birth control pills within three months of becoming pregnant, and 24.8 among mothers who used the pill before realizing they were pregnant.

"The prevalence of birth defects was consistent across each of the oral contraceptive groups as well as when we added in pregnancies that ended as stillbirths or induced abortions," Charlton said. "Similarly, the results were also consistent even when we broke down the birth defects into different subgroups, like limb defects," she added.

In all, the study found that 68 percent of mothers had used birth control pills, but stopped more than three months before pregnancy, and 21 percent had never used them. Also, 8 percent of the women had stopped using oral contraceptives within three months of conception, and 1 percent used them after getting pregnant, the researchers said.

Charlton's team excluded any infants with defects caused by known factors, such as fetal alcohol syndrome or chromosomal abnormalities.

The researchers also accounted for risk factors that could increase the odds of a birth defect. These included the mother's age, household income, level of education, history of birth defects, smoking during pregnancy, use of prescription drugs and hospital admissions.

The study findings were published online Jan. 6 in BMJ.

According to Wu, this study shows that women shouldn't worry that getting pregnant while on a birth control pill will cause an abnormal pregnancy.

SOURCES: Brittany Charlton, Sc.D., instructor, department of epidemiology, Harvard T.H. Chan School of Public Health, Boston; Jennifer Wu, M.D., obstetrics and gynecology, Lenox Hill Hospital, New York City; Jan. 6, 2016, BMJ, online

Copyright © 2016 HealthDay. All rights reserved.

If you've been taking the birth control pill and discover you are pregnant, you may wonder whether this could harm your baby or if there's a chance that it may lead to a miscarriage or stillbirth.

Most research suggests that you need not worry. Some types of birth control may cause complications, but, for the most part, using birth control pills or other hormone delivery devices (such as the Ortho Evra patch or NuvaRing) is relatively safe.

Birth Control Pill and Birth Defects

According to the Food and Drug Administration (FDA), there's no evidence that taking combination birth control pills or progestin-only pills while pregnant will harm your baby in any way, either by increasing the risk of birth defects or causing pregnancy complications.

It's important to note that there has not been a lot of research on this subject. This is not because of oversight or lack of interest. Medical ethics would not allow anyone to conduct research that may place a mother or her unborn baby in harm's way.

Most of the data is derived from epidemiological research comparing mothers who have used birth control pills during early pregnancy with those who haven't. In this regard, there has been little difference in the number of birth defects, miscarriages, or stillbirths between either group.

The CDC notes that progestins taken in early pregnancy slightly increase the risk of hypospadias in boys (a birth defect where the opening of the urethra is not located at the tip of the penis). However, the studies leading to this conclusion are older and were mostly of women taking progestins for infertility or to prevent pregnancy loss and not the low doses of progestins in birth control pills.

If You Think You May Be Pregnant

It's still not recommended that you continue taking birth control if you're pregnant. In the end, every drug you take will be "taken" by your child, as well.

So if you think you may be pregnant, take a pregnancy test to know for sure. If you can't take a pregnancy test for any reason, consider using other forms of contraception (such as condoms or the sponge) until you can.

Pregnancy While On Birth Control

Although abstinence is the only method of birth control that ensures 100% effectiveness for preventing pregnancy, perfect use of contraceptives is nearly 100% effective. Perfect use means that a contraceptive is used correctly every time, while typical use accounts for common human errors, such as forgetting to take a contraceptive pill on time.

With perfect use, the birth control pill is more than 99% successful. With typical use, the birth control pill is about 91% effective. Perfect use of condoms is about 98% effective, while typical use is around 82%.

Long-acting reversible contraceptives (LARCs) such as an intrauterine device (IUD) and permanent contraception methods like tube litigation are more than 99% effective.

Birth Control and Miscarriage Myths

Most birth control methods don't cause any harm to an unborn child when they are used during early pregnancy. There are some common misunderstandings about the difference between birth control and medical abortion pills.

Birth Control Pills

Some people believe that if they continue to take the birth control pill while pregnant, they may have a miscarriage. This is not true, and there has never been any evidence to suggest that. Taking the birth control pill while pregnant doesn't cause a miscarriage.

The hormones in the pill work by stopping ovulation and thickening cervical mucus to prevent sperm from entering the uterus. During early pregnancy, these actions don't contribute to miscarriage or stillbirth.

Emergency Contraception

Another myth is that using emergency contraception (such as Plan B One-Step or the AfterPill) while pregnant may cause the spontaneous termination of your pregnancy. This is again not true. These pills really have no effect once a fertilized egg has been implanted.

Medical Abortion

There are specific medications that can end a pregnancy if desired. This is a form of medical abortion and is it not considered birth control. A medical abortion works through a different method than hormonal birth control. Known as Mifeprex (mifepristone) or RU-486, the abortion pill has been FDA-approved in the United States since 2000.

Risks of Continuing Birth Control

Some birth control methods can cause harm when used during pregnancy. Below is a breakdown of common birth control methods and their risks if used during pregnancy.

COCs or Progestin-Only Pills

Combined estrogen-progestin oral contraceptives (COCs) and progestin-only pills are two different types of birth control pills. COCs contain synthetic forms of estrogen and progesterone, while progestin-only pills contain only synthetic progesterone.

While there's no evidence suggesting birth defects or a miscarriage can occur if you take birth control pills while pregnant, some research suggests that the baby may be at increased risk of wheezing, asthma, and rhinitis.

IUDs

If you have an IUD and become pregnant, there may be complications. Research suggests that if a person chooses to leave their IUD in during pregnancy, their miscarriage risk will increase to around 40%. Moreover, it can raise the likelihood of preterm birth by some 500%.

With these risks in mind, you should call your healthcare provider immediately to have your IUD removed if you become pregnant and decide to continue the pregnancy. Removing the IUD early in a timely fashion can reduce those risks.

Implants, Shots, and Vaginal Rings

There's no evidence that contraceptive methods like implants, injection shots, and vaginal rings cause birth defects or miscarriages if someone is using them during early pregnancy. These forms of birth control typically use the same types of hormones found in birth control pills.

Ectopic Pregnancy

Progestin-only forms of birth control may slightly increase the risk of ectopic pregnancy if they fail to prevent pregnancy. However, there's no higher absolute risk of ectopic pregnancy when compared to using no contraceptive.

Ectopic pregnancy is when a fertilized egg implants in a place other than the lining of the uterus (endometrium).

Symptoms can include:

• Low back pain
• Pain in the abdomen or pelvis
• Abnormal vaginal bleeding

Talk to a health care professional if you have abnormal vaginal bleeding and pelvic pain.

Severe, sudden pain in the pelvis or abdomen, shoulder pain, or fainting are serious symptoms of ectopic pregnancy that need immediate medical attention. These symptoms may indicate that a fallopian tube has ruptured.

Barrier Methods

There are no risks when using barrier methods such as condoms, diaphragms, spermicides, cervical caps, and sponges while pregnant. These methods are used to physically prevent sperm from fertilizing an egg and typically do not involve hormones. Using condoms while pregnant can prevent sexually transmitted infections.

A Word From Verywell

Unintended use of birth control pills during early pregnancy is of low risk. If you are pregnant, discuss any medications, supplements, and over-the-counter products with your healthcare provider. You should discontinue taking birth control pills when you discover you are pregnant.

Frequently Asked Questions

• What happens if you keep taking birth control while pregnant?

  Research suggests that there are risks of miscarriage and preterm birth if an IUD is left in during pregnancy. However, there's no evidence of serious risks from using other forms of birth control during early pregnancy.

How would you know if you were pregnant while taking the pill?

What happens if you get pregnant and still take birth control?

What is the chance of getting pregnant while on birth control?