The information provided below is for readers based in the United States of America. Readers outside of the United States of America should seek the information from local sources.


Chemotherapy drugs can cause birth defects or a miscarriage, especially when taken during the first trimester of pregnancy.

What is chemotherapy?

Chemotherapy is a method for treating cancer that uses medications to kill cancer cells. It can be used to treat cancer by itself in some cases, but it is more commonly used in combination with biological therapy, radiation, or surgery. There are different methods for receiving chemotherapy including injection, intravenous (into a vein), or oral tablets.

What is chemotherapy used to treat?

Chemotherapy is used to treat various types of cancer. It can be used to either cure the disease, prevent cancer from spreading, or to improve symptoms of cancer. When chemotherapy is used in combination with other procedures, it can be used to shrink the size of a tumor prior to surgery or radiation, to make radiation or biological therapy more effective, or to kill cancer cells that remain after radiation or surgery.

How does chemotherapy work?

Chemotherapy works by destroying cancer cells, slowing their growth, or preventing them from spreading throughout the body. Cancer cells grow and multiply rapidly, as opposed to most normal cells in your body which grow at a slower rate. Chemotherapy targets these faster growing cells without harming the rest of your bodys cells. However, your body has some normal cells that also grow rapidly, including cells found in your hair, skin, bone marrow, and intestines. These cells will be affected by chemotherapy and you will notice side effects associated with their destruction or injury. Common side effects experienced from chemotherapy include: hair loss, vomiting, nausea, fatigue, pain, blood disorders, and constipation or diarrhea.     

If I am taking a chemotherapy drug, can it harm my baby?

Chemotherapy drugs that are taken during pregnancy are known to cause birth defects or death of the baby. During the first trimester of pregnancy, your baby is at the highest risk for birth defects or death from a chemotherapy drug. There are few studies available on the risks of these medications in human babies, but there is evidence of major birth defects, spontaneous abortions, and miscarriages in expecting moms who use chemotherapy drugs.    

Exposure to a chemotherapy drug within the first 4 weeks of pregnancy can result in the death of your baby. In this early stage, your baby is mostly composed of rapidly growing cells. Chemotherapy drugs can attack these cells and cause a spontaneous abortion.

If chemotherapy drugs are given after 4 weeks and still within the first trimester, your baby will have an increased risk for major birth defects. This is the period where your babys external structures and internal organs are first developing and are most vulnerable. Chemotherapy is not recommended during the first trimester of pregnancy if it can be avoided.

Chemotherapy that is given in the second and third trimesters of pregnancy may still increase the risk for birth defects and other health problems in your baby. Although the highest risk for major birth defects occurs in the first trimester, your babys brain, reproductive system, and ears continue to develop into the later stages of pregnancy and are still at risk. Additionally, chemotherapy can cause babies to be born prematurely, smaller than normal, or stillborn.These drugs can also cause health problems in your baby, such as difficulty breathing, heart problems, reduced learning ability, and mental retardation. Furthermore, chemotherapy that is taken near the delivery date can increase the risk that your baby will be born with blood disorders. Chemotherapy should be avoided 3 weeks prior to the delivery date or after 35 weeks of pregnancy.

Your doctor will determine if chemotherapy is necessary for your treatment or if it can be delayed until after the birth of your baby. If chemotherapy is required, your doctor can help you choose a drug that may pose less of a risk to your baby. There are many different types of chemotherapy drugs, with some shown to be safer than others when used during pregnancy. Each chemotherapy drug will differ in how much it crosses the placenta and exposes your baby to its harmful effects.

Bottom line: Chemotherapy drugs should be avoided during pregnancy because they can increase the risk of birth defects and death to the baby. However, there are cases where chemotherapy may be required to ensure the health of the mom. In these cases, your doctor can help you select a drug that may present a lower risk to your baby.

If I am taking a chemotherapy drug and become pregnant, what should I do?

If you become pregnant while taking a chemotherapy drug, you should contact your doctor immediately. Your doctor will need to determine if chemotherapy should be continued for your safety or if the medication can be discontinued until after delivery. Based on how far you are into your pregnancy, your doctor will discuss the possible risks to your baby and the options available to you. You may also have an ultrasound to determine if your baby shows signs of having any major birth defects.

If I am taking a chemotherapy drug, can I safely breastfeed my baby?

If you are taking chemotherapy drugs, breastfeeding is considered unsafe and is not recommended by the CDC. When these drugs pass into breast milk, they expose your baby to their toxic effects. Each chemotherapy drug may pass into breast milk in different amounts and can have serious side effects in your baby.    

Bottom line: Moms who are taking chemotherapy drugs should not breastfeed their baby.

If I am taking a chemotherapy drug, will it be more difficult to get pregnant?

Women who are taking chemotherapy medications should not try to get pregnant.  A pregnancy that starts while a women is taking chemotherapy drugs can cause significant harm to the baby and may result in severe birth defects or death. It is important for women who are taking chemotherapy drugs to use extremely effective birth control methods. Additionally, if your male partner is taking a chemotherapy drug, he should not try to father a child. Men taking chemotherapy must utilize effective birth control methods (condoms). Chemotherapy drugs can stay in a mans semen for several months after treatment has ended and increase the risk of birth defects in babies who are exposed to these drugs.

Fertility Problems in Men and Women:

Chemotherapy can cause permanent infertility in women. These drugs can harm the ovaries and lead to primary ovarian insufficiency (POI), a condition where the ovaries stop releasing eggs and estrogen. POI can either be temporary, with fertility returning after chemotherapy treatment, or it can be permanent and result in infertility. Women with POI may have irregular or no menstrual cycles, night sweats, hot flashes, and vaginal dryness. Infertility may be more likely to occur in older women who are closer to the age of menopause. Women who will be starting chemotherapy should ask their doctor about fertilization preservation options. You can read more about fertility preservation here.

Chemotherapy can also cause infertility in men. These drugs can kill sperm cells and potentially result in permanent infertility. If fertility is maintained, sperm production will be decreased following chemotherapy. It usually takes 1 to 4 years for some production of sperm to return, but it could take up to 10 years. Chemotherapy also damages the genetic material in sperm. Although it is unknown if these damaged cells will increase the risk that the baby will have serious problems, healthcare providers usually recommend waiting 2 to 5 years after chemotherapy before attempting to father a child. This allows the damaged sperm to be replaced. Men who will be starting chemotherapy may w
ant to talk with their doctor about options to preserve sperm.

If I am taking a chemotherapy drug, what should I know?

Chemotherapy should be avoided during pregnancy if possible, especially during the first trimester and 3 weeks prior to delivery. These drugs can cause major birth defects or death to your baby. Women who are not pregnant and are taking chemotherapy medications should utilize extremely effective birth control methods and avoid becoming pregnant. Additionally, if your male partner is taking a chemotherapy agent, he should not try to conceive and should also utilize proper birth control methods.

Moms who are taking chemotherapy drugs should not breastfeed their baby. These medications can cause serious side effects in the breastfed baby.

Chemotherapy agents can cause permanent infertility in both men and women. Men or women who are starting a chemotherapy drug can ask their doctors about ways to preserve fertilization.

If I am taking any medication, what should I know?

This report provides a summary of available information about the use of chemotherapy during pregnancy and breastfeeding. Content is from the product label unless otherwise indicated.

You may find Pregistry’s expert reports about cancer here .  Additional information can also be found in the resources below. 

Resources for chemotherapy during pregnancy and breastfeeding:

For more information about chemotherapy during and after pregnancy, contact (800-994-9662 [TDD: 888-220-5446]) or check the following links:


Read the whole report
General information

It is very common for women to worry about having a miscarriage or giving birth to a child with a birth defect while they are pregnant. Many decisions that women make about their health during pregnancy are made with these concerns in mind.

For many women these concerns are very real. As many as 1 in 5 pregnancies end in a miscarriage, and 1 in 33 babies are born with a birth defect. These rates are considered the background population risk, which means they do not take into consideration anything about the health of the mom, the medications she is taking, or the family history of the mom or the baby’s dad. A number of different things can increase these risks, including taking certain medications during pregnancy.

It is known that most medications, including over-the-counter medications, taken during pregnancy do get passed on to the baby. Fortunately, most medicines are not harmful to the baby and can be safely taken during pregnancy. But there are some that are known to be harmful to a baby’s normal development and growth, especially when they are taken during certain times of the pregnancy. Because of this, it is important to talk with your doctor or midwife about any medications you are taking, ideally before you even try to get pregnant.

If a doctor other than the one caring for your pregnancy recommends that you start a new medicine while you are pregnant, it is important that you let them know you are pregnant.

If you do need to take a new medication while pregnant, it is important to discuss the possible risks the medicine may pose on your pregnancy with your doctor or midwife. They can help you understand the benefits and the risks of taking the medicine.

Ultimately, the decision to start, stop, or change medications during pregnancy is up to you to make, along with input from your doctor or midwife. If you do take medications during pregnancy, be sure to keep track of all the medications you are taking.