This sheet is about exposure to the ACAM2000® smallpox vaccine in pregnancy and while breastfeeding. This information is based on available published research. It should not take the place of medical care and advice from your healthcare provider.

What is the ACAM2000®smallpox vaccine?

The ACAM2000® vaccine helps protect against smallpox, mpox, and other diseases caused by orthopoxviruses. The vaccine helps the body’s immune system learn how to protect itself (make antibodies) against these viruses (orthopoxviruses) in general.

ACAM2000® does not contain live virus that could cause smallpox or mpox. However, this vaccine does contain a live virus from the orthopoxvirus family called vaccinia virus.

ACAM2000® can be given before or after exposure to an orthopoxvirus to help prevent illness or reduce symptoms. It is given as a single dose with a special kind of needle that makes multiple skin pricks on a small area. The area forms a small wound or lesion that may take up to 6 weeks to fully heal. During that time, the lesion must stay covered since vaccinia virus can spread from this area to other parts of the body or to other people before the lesion is fully healed.

Since ACAM2000® contains live vaccinia virus, there is a small chance that getting the vaccine could cause illness in certain people. The Centers for Disease Control and Prevention (CDC) does not recommend ACAM2000® for most women who are pregnant or breastfeeding, have weakened immune systems or certain underlying health conditions, or for those who live with or have close contact with these groups of people.

When there is a chance of being exposed to the virus that causes smallpox or another orthopoxvirus, it is important to continue taking steps to avoid exposure even after being vaccinated. The CDC has information on smallpox here: https://www.cdc.gov/smallpox/about/index.html and on mpox here: https://www.cdc.gov/mpox/. MotherToBaby has a fact sheet about mpox in pregnancy and breastfeeding at https://mothertobaby.org/fact-sheets/mpox/.

Is the ACAM2000® vaccine recommended for women who are pregnant?

ACAM2000® is not recommended for most women who are pregnant during non-emergency situations. This is because of the very rare chance of a serious infection in the developing baby called fetal vaccinia.

ACAM2000® is also not recommended for those who live with or have close contact with women who are pregnant. Another type of mpox/smallpox vaccine, called JYNNEOS™, is available in the United States that is not associated with fetal vaccinia. You can read more about JYNNEOS™ on the MotherToBaby fact sheet at https://mothertobaby.org/fact-sheets/mpox-smallpox-vaccine-jynneos/. Talk with your healthcare provider about what vaccine is right for you.

Does getting the ACAM2000® vaccine make it harder to get pregnant?

Studies have not been done to see if ACAM2000® can make it harder to get pregnant.

I just got the ACAM2000® vaccine. How long do I need to wait before I get pregnant?

To avoid the chance of fetal vaccinia, it has been recommended to wait 4 to 6 weeks after getting ACAM2000®, and until the lesion from the vaccine has fully healed, before trying to get pregnant.

Does getting the ACAM2000® vaccine increase the chance of miscarriage?

Miscarriage is common and can occur in any pregnancy for many different reasons. The ACAM2000® vaccine itself is not associated with an increased chance of miscarriage. However, cases of fetal vaccinia have been associated with miscarriage.

Does getting the ACAM2000® vaccine increase the chance of birth defects?

Birth defects can happen in any pregnancy for different reasons. Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect. We look at published data to try to understand if an exposure, like the ACAM2000® vaccine, might increase the chance of birth defects in a pregnancy.

Information on pregnancies accidentally exposed to live virus smallpox vaccines does not suggest an increased chance for birth defects. This information includes women who received the vaccine before they knew they were pregnant or conceived within 4 weeks of getting the vaccine.

Fever is a possible side effect of the ACAM2000® vaccine. A high fever in the first trimester can increase the chance of certain birth defects. Acetaminophen is usually recommended to reduce fever during pregnancy. For more information about fever and pregnancy, see the MotherToBaby fact sheet about fever/hyperthermia at https://mothertobaby.org/fact-sheets/hyperthermia-pregnancy/.

Does getting the ACAM2000® vaccine in pregnancy increase the chance of other pregnancy-related problems?

The ACAM2000® vaccine itself is not expected to increase the chance of pregnancy-related problems, such as preterm delivery (before 37 weeks of pregnancy) or low birth weight (weighing less than 5 pounds, 8 ounces (2500 grams) at birth). However, cases of fetal vaccinia have been associated with stillbirth, preterm delivery, and infant death. Infants who survive fetal vaccinia can have scars on the skin from the pox marks caused by the virus.

Does getting the ACAM2000® vaccine in pregnancy affect future behavior or learning for the child?

Studies have not been done to see if ACAM2000® affects future behavior or learning for the child.

Does getting ACAM2000® during pregnancy protect the baby from mpox after delivery?

It is not known if getting the ACAM2000® vaccine during pregnancy would protect the baby from mpox after delivery.

Breastfeeding and the ACAM2000® vaccine:

Studies have not been done to see if ACAM2000® passes into breast milk. However, a vaccinated woman could pass the vaccinia virus to an infant through close contact until the lesion from the vaccine is completely healed. For this reason, and because another kind of mpox/smallpox vaccine is available, the CDC recommends that ACAM2000® not be given to most women who are breastfeeding. If you received the ACAM2000® vaccine and are breastfeeding or pumping, talk to your healthcare provider about the best way to feed your baby until the lesion from the vaccine is completely healed.

It is not known if the antibodies (protection) a woman makes after getting an ACAM2000® vaccine can pass through the breast milk and protect the baby against mpox.

Talk to your healthcare provider about all of your breastfeeding questions.

If a man gets the ACAM2000® vaccine, could it affect fertility or increase the chance of birth defects?

Studies have not been done in men to see if the ACAM2000® vaccine could affect fertility (ability to get a woman pregnant) or increase the chance of birth defects above the background risk.

People who get ACAM2000® could pass the vaccinia virus to others through close contact or through shared items like towels and bedding until the lesion caused by the vaccine is completely healed. If a woman who is pregnant is exposed to the virus in this way, it could increase the chance of serious complications if the baby develops fetal vaccinia. For this reason, and because another type of mpox/smallpox vaccine is available, it is generally recommended that men who live with women who are pregnant not get the ACAM2000® vaccine.

If a man does get the ACAM2000® vaccine, it is recommended to wait 4 weeks after getting the vaccine, and until the lesion from the vaccine has fully healed, before trying to get a partner pregnant. If their partner is already pregnant, they should isolate from their partner for 4 weeks after getting the vaccine, and until the lesion from the vaccine is fully healed. They should also take steps to keep their clothing, bedding, bandages, and other contaminated items away from their partner.

For more information on paternal exposures, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.

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This sheet is about exposure to diphenhydramine in pregnancy and while breastfeeding. This information is based on published research studies. It should not take the place of medical care and advice from your healthcare provider. 

What is diphenhydramine?

Diphenhydramine is an antihistamine medication that has been used to treat allergy symptoms, nausea, motion sickness, insomnia, itchy skin, migraine, and tremors related to Parkinson’s disease. Diphenhydramine is found in many prescriptions and over the counter products. Some brand names for diphenhydramine include Benadryl®, Dormin®, Unisom®, Sominex®, and Nytol®. 

Sometimes when people find out they are pregnant, they think about changing how they take their medication, or stopping their medication altogether. However, it is important to talk with your healthcare providers before making any changes to how you take your medication. Your healthcare providers can talk with you about the benefits of treating your condition and the risks of untreated illness during pregnancy. 

I take diphenhydramine. Can it make it harder for me to get pregnant? 

It is not known if diphenhydramine can make it harder to get pregnant. 

Does taking diphenhydramine increase the chance of miscarriage? 

Miscarriage is common and can occur in any pregnancy for many different reasons. Results from one study did not show an increased chance of miscarriage with the use of antihistamines, including diphenhydramine, in early pregnancy. 

Does taking diphenhydramine increase the chance of birth defects? 

Birth defects can happen in any pregnancy for different reasons. Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect. We look at research studies to try to understand if an exposure, like diphenhydramine, might increase the chance of birth defects in a pregnancy. 

A few studies have suggested a higher chance of birth defects when diphenhydramine is used during the first trimester. However, these studies do not all agree, and no consistent pattern of birth defects has been noted. There are also several studies that reported no increased chance of birth defects with the use of diphenhydramine in early pregnancy.  

Does taking diphenhydramine in pregnancy increase the chance of other pregnancy-related problems? 

Occasional use of diphenhydramine at recommended doses is not expected to increase the chance of other pregnancy-related problems, such as preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth).  

There are reports of other issues, including uterine contractions and, very rarely, fetal death with the use of diphenhydramine in the third trimester. However, these reports usually involve using more of the medication than is recommended or using it for longer than the recommended time.  

Can I take diphenhydramine with a benzodiazepine?

There is a single human report and animal data that has suggested that the combination of a medication called temazepam (a benzodiazepine) and diphenhydramine might increase the chance of stillbirth or infant death shortly after birth. It has been recommended that these two medications not be used together during pregnancy. People taking temazepam should talk with their healthcare provider before taking diphenhydramine during their pregnancy. MotherToBaby has a fact sheet on temazepam here: https://mothertobaby.org/fact-sheets/temazepam-restoril/.

I need to take diphenhydramine throughout my entire pregnancy. Will it cause symptoms in my baby after birth? 

The use of diphenhydramine during pregnancy can cause temporary symptoms in newborns soon after birth. These symptoms are sometimes referred to as withdrawal. There are a few reports of withdrawal symptoms (tremors and diarrhea) in infants who were exposed to diphenhydramine daily throughout pregnancy. Not all babies exposed to diphenhydramine will have these symptoms. It is important that your healthcare providers know you are taking diphenhydramine so that if symptoms occur your baby can get the care that is best for them. 

Does taking diphenhydramine in pregnancy affect future behavior or learning for the child?  

It is not known if diphenhydramine can increase the chance of behavior or learning issues for the child. 

Breastfeeding while taking diphenhydramine: 

Diphenhydramine passes into breastmilk in small amounts. This medication can cause sleepiness in adults as well as the nursing baby. Two studies reported irritability and changes in sleep patterns in breastfed babies exposed to antihistamines, including diphenhydramine. Short-term or occasional use of diphenhydramine is not expected to increase the chance of side effects. If you suspect the baby has any symptoms (irritability, changes in sleep patterns), contact the child’s healthcare provider. If you need to take an antihistamine regularly, talk with your healthcare provider about which medication is best for you. Be sure to talk to your healthcare provider about all your breastfeeding questions.  

If a man takes diphenhydramine, could it affect fertility or increase the chance of birth defects?   

Studies have not been done to see if diphenhydramine could affect men’s fertility (ability to get a partner pregnant) or increase the chance of birth defects. In general, exposures that fathers or sperm donors have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/. 

Please click here for references.

This sheet is about having atopic dermatitis in a pregnancy or while breastfeeding. This information is based on published research studies. It should not take the place of medical care and advice from your healthcare provider. 

What is atopic dermatitis? 

Atopic dermatitis (also called atopic eczema or eczema) is a medical condition that makes skin red and itchy. Symptoms can include dry and itchy skin, red to brownish-gray patches (especially on the hands, feet, ankles, wrists, neck, upper chest, eyelids, inside the bend of the elbows and knees), small, raised bumps that might leak fluid and crust over when scratched, thickened, cracked, or scaly skin, and/or raw/sensitive skin from scratching.  

Atopic dermatitis can be mild, moderate, or severe. For most people, atopic dermatitis starts in childhood, but it can also start in adulthood. For some people, atopic dermatitis is a chronic disorder with symptoms that can be ongoing for a period and then symptoms go away but come back on and off (flares).   

I have atopic dermatitis. Can it make it harder for me to get pregnant? 

It is not known if atopic dermatitis can make it harder to get pregnant. One study suggests that atopic dermatitis might make it harder to get pregnant. 

Does having atopic dermatitis increase the chance of miscarriage? 

Miscarriage is common and can occur in any pregnancy for many different reasons. Studies have not been done to see if atopic dermatitis can increase the chance of miscarriage.  

Does having atopic dermatitis increase the chance of birth defects? 

Birth defects can happen in any pregnancy for different reasons. Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect. We look at research studies to try to understand if atopic dermatitis might increase the chance of birth defects in a pregnancy. It is not known if atopic dermatitis can increase the chance of birth defects.  

Does having atopic dermatitis increase the chance of other pregnancy-related problems? 

It is not known if atopic dermatitis can increase the chance of pregnancy-related problems, such as preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth). There have been reports of atopic dermatitis symptoms becoming worse or flaring during the 2nd or 3rd trimester of their pregnancy. 

One study suggests that having atopic dermatitis can increase the chance of high blood pressure in people who are not pregnant. High blood pressure can increase the risks to a pregnancy. If you have questions or concerns about your blood pressure, talk with your healthcare provider.  

Does having atopic dermatitis in pregnancy affect future behavior or learning for the child? 

Studies have not been done to see if having atopic dermatitis can increase the chance of behavior or learning issues for the child. 

Can I take my prescribed medication for atopic dermatitis during pregnancy?

It is important that you talk with your healthcare providers about your medication when planning pregnancy, or as soon as you learn that you are pregnant. Sometimes when people find out they are pregnant, they think about changing how they take their medication or stopping their medication altogether. However, it is important to talk with your healthcare providers before making any changes to how you take your medication. Your healthcare providers can talk with you about the benefits of treating your condition and the risks of untreated illness during pregnancy. There are a variety of medications that are used to treat atopic dermatitis. Information on specific medications can be found in our fact sheets at https://mothertobaby.org/fact-sheets/ or by contacting a MotherToBaby specialist at 866.626.6847. 

Breastfeeding while having atopic dermatitis:

Atopic dermatitis does not appear to affect a person’s ability to breastfeed. Talk with your healthcare provider and your baby’s pediatrician about any medications you take for atopic dermatitis while breastfeeding. Information on specific medications can be found in our fact sheets at https://mothertobaby.org/fact-sheets/ or by contacting a MotherToBaby specialist at 866.626.6847. Be sure to talk with your healthcare provider about all your breastfeeding questions.  

If a man has atopic dermatitis, could it affect fertility or increase the chance of birth defects? 

One study suggests that men with atopic dermatitis could have more trouble with fertility (ability to get a partner pregnant) then men without the condition. Studies have not been done to see if atopic dermatitis could increase the chance of birth defects. In general, exposures that fathers or sperm donors have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/. 

           MotherToBaby is currently conducting a study looking at eczema (moderate-to-severe)/atopic dermatitis in pregnancy. If you are interested in taking part in this study,                 please call 1-877-311-8972 or sign up at https://mothertobaby.org/join-study/. 

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This sheet is about exposure to vitamin C in pregnancy and while breastfeeding. This information is based on available published research studies. It should not take the place of medical care and advice from your healthcare providers.

What is vitamin C?

Vitamin C is also known as ascorbic acid and dehydroascorbic acid. It is an essential vitamin. Essential vitamins are nutrients that the body cannot make, so people need to get vitamin C from other sources. Vitamin C is naturally found in some foods such as fruits and vegetables. Vitamin C is also available as a dietary supplement.

What is the Dietary Reference Intake of vitamin C for women who are pregnant?

The Recommended Dietary Allowance (RDA) is the amount people should aim to get each day. It is not recommended to take more than the RDA in a day. The Tolerable Upper Intake Level (UL) is the dose that people can start to have side effects.

	Recommended Daily Allowance (RDA)	Upper Limit (UL)
Pregnant and 14 to 18 years old	80 mg per day	2,000 mg per day
Pregnant and 19 years old or older	85 mg per day	2,000 mg per day

When looking at daily intake, remember to count amounts from foods, drinks, and from supplements. There are resources available online that list amounts of vitamin C typically found in foods. Labels on supplements will list the amount of vitamin C in the product.

Most people can get enough vitamin C from a balanced diet. It is unlikely that you will get too much vitamin C if your only source of vitamin C is in your food and drink.

People who have exposure to cigarette smoke or who have medical conditions that might affect how their body absorbs vitamins (such as cancer, eating disorders, kidney disease, malabsorption, or substance misuse) should talk with their healthcare providers about their specific nutritional needs.

I take vitamin C. Can it make it harder for me to get pregnant?

Vitamin C has not been well studied to see if it can make it harder to get pregnant. However, if a woman is getting recommended amounts of vitamin C (not too much and not too little) it would be unlikely to make it harder to get pregnant. Two studies have suggested that vitamin C intake might help to lower the chance of infertility (inability to get pregnant).

I just found out I am pregnant. Should I stop taking vitamin C?

It is not recommended to take more than the RDA of vitamins unless you are doing so under the care of your healthcare provider. Talk with your healthcare providers about all supplements/vitamins that you take. Have the bottles or photos of the labels with you so that all ingredients and their recommended daily levels can be reviewed. Products that contain herbal supplements are typically not recommended during pregnancy. For more information on herbal products please see our fact sheet at: https://mothertobaby.org/fact-sheets/herbal-products-pregnancy/.

Does taking vitamin C increase the chance of miscarriage?

Miscarriage is common and can occur in any pregnancy for many different reasons. While vitamin C supplements and miscarriage have not been well studied, if a woman is getting the recommended amounts of vitamin C (not too much and not too little) it would be unlikely that vitamin C would increase the chance for miscarriage. Studies where vitamin C was given to women who were pregnant prior to 20 weeks in an effort to reduce miscarriage or other pregnancy complications; no reduction in miscarriage was found.

Does taking vitamin C increase the chance of birth defects?

Birth defects can happen in any pregnancy for different reasons. Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect. We look at research studies to try to understand if an exposure, like too much or too little vitamin C intake, might increase the chance of birth defects in a pregnancy.

Vitamin C intake below the RDA or at doses higher than the UL is not known to increase the chance for birth defects. However, vitamin C has not been well studied in relation to birth defects. It is recommended that people take the RDA of vitamin C unless their healthcare provider prescribes something different.

Does taking vitamin C in pregnancy increase the chance of other pregnancy-related problems?

Several studies looked at the use of vitamin C supplementation in the second and third trimester of pregnancy to try to lower the chance of pregnancy-related complications such as preterm delivery (birth before week 37), low birth weight (weighing less than 5 pounds 8 ounces [2500 grams] at birth), and preeclampsia (high blood pressure and problems with organs, such as the kidneys), which can lead to seizures (called eclampsia). These studies did not consistently find benefit or harm to the baby from this supplementation. There is a report of 2 babies exposed to levels higher than the RDA (more than 400mg per day during pregnancy). After delivery, these 2 babies had rapid metabolism of vitamin C and then showed signs of vitamin C deficiency.

Does taking vitamin C in pregnancy affect future behavior or learning for the child?

Studies have not been done to see if vitamin C intake below the RDA or at doses higher than the UL can increase the chance of behavior or learning issues for the child.

Breastfeeding while taking vitamin C:

Vitamin C is a normal part of breastmilk. Women who are breastfeeding should continue to get the daily recommended amount of vitamin C. The RDA for breastfeeding is different from pregnancy.

	Recommended Daily Allowance (RDA)	Upper Limit (UL)
Breastfeeding and 14 to 18 years old	115 mg per day	2,000 mg per day
Breastfeeding and 19 years old or older	120 mg per day	2,000 mg per day

People who have exposure to cigarette smoke or who have medical conditions that might affect how their body absorbs vitamins (such as cancer, eating disorders, kidney disease, malabsorption, or substance misuse) should talk with their healthcare providers about their specific nutritional needs. Be sure to talk to your healthcare provider about all of your breastfeeding questions.

If a man takes vitamin C, could it affect fertility or increase the chance of birth defects?

A few studies have found that vitamin C might help to improve fertility (ability to get a woman pregnant) for some men but not for others. Men who are experiencing infertility should discuss treatment options with their healthcare providers. In general, exposures that men have are unlikely to increase the risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.

Please click here for references.

This sheet is about exposure to carbon monoxide in pregnancy and while breastfeeding. This information is based on  published research studies. It should not take the place of medical care and advice from your healthcare provider. 

What is carbon monoxide?

Carbon monoxide is a gas. It has no color, smell, or taste. Small amounts of carbon monoxide are typically found in our bodies and in the air we breathe. Larger amounts of carbon monoxide can be released from poorly working fuel burning appliances like furnaces, water heaters, and gas stoves. Exhaust from cars and other vehicles release carbon monoxide.  

How can carbon monoxide get into my body?

Carbon monoxide can enter the body by breathing it in (inhalation). Breathing in any type of smoke can lead to more carbon monoxide in your body. 

What is carbon monoxide poisoning?

Carbon monoxide poisoning happens when too much carbon monoxide gets into the body. When there is too much carbon monoxide in the body, the blood carries less oxygen to the organs. Symptoms of carbon monoxide poisoning can include headache, nausea, vomiting, muscle weakness, upset stomach, and dizziness. More severe symptoms are confusion, stumbling or falling, chest pain, sleepiness, and passing out (loss of consciousness). Severe carbon monoxide poisoning can cause death. 

How can I lower the chance of carbon monoxide exposure or poisoning?

• Make sure home appliances that burn fuels are properly installed, vented, and maintained 

• Have working carbon monoxide and smoke detectors in your home that are battery operated or backed up by batteries in case there is a power outage 

• Use generators outside only, away from the home/windows/doors  

• Avoid heating your home with an oven  

• Avoid leaving a car running in an attached garage 

• Avoid cigarette smoke (For more information, please see the MotherToBaby fact sheet on cigarette smoking at https://mothertobaby.org/fact-sheets/cigarette-smoking-pregnancy/.) 

What should I do if I am pregnant and think I have carbon monoxide poisoning?

Carbon monoxide poisoning is a medical emergency. If you have any symptoms that you think are from carbon monoxide, you should be taken to the emergency room right away. In pregnancy, the carbon monoxide might not get into the fetus’ blood right away. However, once it does, it takes much longer for the fetus to clear the carbon monoxide than it would an adult. If you do have carbon monoxide poisoning, you might be given treatment to help you and the fetus get rid of the carbon monoxide. The source of carbon monoxide should be found, and the problem should be fixed as soon as possible to stop further exposure. 

Can exposure to carbon monoxide make it harder for me to get pregnant?

Studies have not been done to see if carbon monoxide exposure can make it harder to get pregnant. 

Does exposure to carbon monoxide increase the chance of miscarriage?

Miscarriage is common and can occur in any pregnancy for many different reasons. Carbon monoxide might be linked to a higher chance of miscarriage. Effects can depend on when (timing) in pregnancy someone is exposed and how much (dose) carbon monoxide they are exposed to. 

Does exposure to carbon monoxide increase the chance of birth defects? 

Birth defects can happen in any pregnancy for different reasons. Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect. We look at research studies to try to understand if an exposure, like carbon monoxide, might increase the chance of birth defects in a pregnancy.  

There are reports of babies being born with birth defects after exposure to carbon monoxide during pregnancy. However, most pregnancies with carbon monoxide exposure do not have birth defects, and no pattern of birth defects has been linked to carbon monoxide poisoning. The main concerns with carbon monoxide poisoning during pregnancy are the chance of pregnancy loss and possible harm to fetal brain development. 

Does exposure to carbon monoxide increase the chance of other pregnancy-related problems?

Some studies suggest that exposure to carbon monoxide in pregnancy can increase the chance of other pregnancy-related problems, such as preterm delivery (birth before week 37), low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth), and stillbirth. There are also reports of healthy outcomes after pregnancies with carbon monoxide poisoning.  

Does exposure to carbon monoxide affect future learning or behavior of the child? 

Carbon monoxide exposure during pregnancy might affect fetal brain development, which could increase the chance of learning or behavior problems later in life. There are reports of healthy outcomes in pregnancies after carbon monoxide poisoning. Effects can depend on when (timing) in pregnancy someone is exposed and how much (dose) carbon monoxide they are exposed to. 

Breastfeeding and exposure to carbon monoxide:

There are no human studies looking at carbon monoxide exposure during breastfeeding. Absorption of carbon monoxide from swallowing breastmilk is thought to be unlikely. If you get carbon monoxide poisoning, talk to your healthcare provider about breastfeeding. Be sure to talk to your healthcare provider about all of your breastfeeding questions.  

If a man is exposed to carbon monoxide, could it affect fertility or increase the chance of birth defects?

Studies have not been done in humans to see if carbon monoxide could affect men’s fertility (ability to get a partner pregnant) or increase the chance of birth defects. Animal studies show carbon monoxide exposure can reduce how many sperm are formed, which could affect fertility. In general, exposures that men have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.  

Please click here to view references.