This sheet is about exposure to acyclovir/ valacyclovir 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 providers. 

What is acyclovir/valacyclovir?  

Acyclovir (Zovirax®) is an antiviral medication that has been used to treat symptoms from cold sores and genital herpes caused by the herpes virus. It is also prescribed to treat chickenpox and shingles. Acyclovir can help relieve the pain and help the healing of sores or blisters. Valacyclovir (Valtrex®) is like acyclovir and is used to treat the same types of infections. Valacyclovir changes to acyclovir once inside the body. 

Acyclovir/valacyclovir has been prescribed during pregnancy when a woman has a primary (first time) genital herpes infection. Primary infections can be life-threatening or lead to complications in a pregnancy. A rare but serious lung complication caused by chickenpox virus infection called varicella pneumonia might also require treatment with these medications. MotherToBaby has a fact sheet on varicella infection (chickenpox) here: https://mothertobaby.org/fact-sheets/varicella/. 

Sometimes when women 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 acyclovir/valacyclovir. Can it make it harder for me to get pregnant? 

It is not known if acyclovir/valacyclovir can make it harder to get pregnant. 

Does taking acyclovir/valacyclovir increase the chance of miscarriage? 

Miscarriage is common and can occur in any pregnancy for many different reasons. Studies have not found an increased chance of miscarriage with acyclovir/valacyclovir use. 

Does taking acyclovir/valacyclovir 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 acyclovir/valacyclovir, might increase the chance of birth defects in a pregnancy. 

Taking acyclovir/valacyclovir during pregnancy is not expected to increase the chance of birth defects. Studies have not found an increased chance of birth defects in over 500 births reviewed by the manufacturer and the Centers for Disease Control and Prevention (CDC). Another study found no increased chance of birth defects in more than 1,500 infants exposed to acyclovir and over 200 infants exposed to valacyclovir during the first trimester of pregnancy. 

Does taking acyclovir/valacyclovir in pregnancy increase the chance of other pregnancy-related problems? 

It is not known if acyclovir/valacyclovir use can increase the chance of other pregnancy-related problems, such as preterm delivery (birth before week 37 of pregnancy) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth). However, clinical case reports have not reported increased chances of preterm delivery, which is reassuring. It is important to note that untreated infections could cause problems for the woman who is pregnant, the pregnancy, and the newborn. Be sure to talk to a healthcare provider if you have or suspect you have an untreated infection during pregnancy.  

Does taking acyclovir/valacyclovir in pregnancy affect future behavior or learning for the child?   

Studies have not been done to see if acyclovir/valacyclovir can affect a child’s future behavior or learning after exposure during pregnancy. 

Breastfeeding while taking acyclovir/valacyclovir: 

Acyclovir passes into breast milk in small amounts. Acyclovir is commonly used in newborns and is not expected to cause problems for breastfed babies. If you apply acyclovir cream or ointment to your breast, clean the area before breastfeeding. Be sure to talk to your healthcare provider about all your breastfeeding questions. 

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

Information on the effects of acyclovir/valacyclovir on men’s fertility (ability to make healthy sperm) is limited. One study in 20 men found that high doses of acyclovir for 6 months did not lower sperm production. Studies have not been done to know if acyclovir/valacyclovir can 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 exposure to iodine-131 in pregnancy and while breastfeeding. This sheet will not cover environmental exposures that might occur due to accidents in nuclear plants or inappropriate handling of radioactive iodine-131. This information is based on published research studies. It should not take the place of medical care and advice from your healthcare providers. 

What is iodine-131? 

Iodine-131 (also known as I-131) is a radioisotope of iodine. Radioisotopes release radiation. Iodine-131 concentrates in the thyroid gland, and has been used in medical diagnostic procedures, to treat thyroid cancer, and to remove the thyroid in people with hyperthyroidism (a condition in which the body makes too much thyroid hormone). Some people refer to this as radioactive iodine therapy or radioiodine treatment. 

The product label for iodine-131 recommends women who are pregnant or breastfeeding not use this medication. 

Some people who receive iodine-131 treatment can have high levels of radiation for a short time after receiving treatment. Talk with your healthcare team about safety precautions to help reduce radiation exposure to other people, such as women who are pregnant and children. The length of time that you will need to follow these precautions will depend on your dose of I-131, among other factors. In general, people might need to follow safety precautions from 3 days to 2 weeks. The American Thyroid Association has an information sheet that includes this information at: https://www.thyroid.org/wp-content/uploads/patients/brochures/Radioactive_iodine_brochure.pdf.  

I received iodine-131. How long does the drug stay in my body? 

The time it takes the body to metabolize (to process) medication is not the same for everyone. In healthy adults, it takes up to 48 days, on average, for most of the iodine-131 to be gone from the body. However, the American Thyroid Association has recommended postponing pregnancy for at least 6 to 12 months after receiving iodine-131. Having your thyroid hormone levels in the appropriate range is important for fertility (ability to get pregnant) and for a healthy pregnancy. 

I received iodine-131. Can it make it harder for me to get pregnant?  

Some women who had radioiodine therapy reported having menstrual cycle irregularities after treatment. Women with menstrual cycle irregularities might have a harder time getting pregnant. 

Does receiving iodine-131 increase the chance for miscarriage in future pregnancies?   

Miscarriage is common and can occur in any pregnancy for many different reasons. One study reported a higher chance of miscarriage in pregnancies that were conceived during the 12 months after treatment with iodine-131. There does not appear to be an increased chance for miscarriage among women who were treated with I-131 at least 12 months before a pregnancy. 

Does receiving iodine-131 increase the chance of having a baby with a birth defect? 

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 iodine-131, might increase the chance of birth defects in a pregnancy. 

Most reports on women who received iodine-131 prior to a pregnancy showed no increase in the chance of birth defects.  

It has been recommended to avoid iodine-131 during pregnancy, when possible. The fetus can absorb radioactive iodine into their thyroid starting at about 10 weeks of pregnancy, and this can result in severe thyroid gland damage and thyroid hormone deficiency in the fetus. Thyroid hormones are very important for fetal development. 

Could iodine-131 cause other pregnancy complications?  

Most studies do not show an increase in pregnancy complications such as preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth) if the iodine-131 is received prior to the pregnancy.  Use of iodine-131 during pregnancy is avoided when possible. 

Does taking iodine-131 in pregnancy cause long-term problems in behavior or learning for the baby? 

It is not known if medical iodine-131 tests and treatments can increase the chance for behavior or learning issues for the child. Iodine-131 is avoided during pregnancy when possible because iodine-131 can affect the baby’s thyroid and thyroid hormone levels. Babies with thyroid hormones that are too low have an increased risk for developmental delays. 

Can I breastfeed while taking iodine-131?  

The product label for iodine-131 recommends women who are pregnant or breastfeeding not use this medication. In addition, the American Thyroid Association (ATA) does not recommend breastfeeding while being treated with I-131 to protect the baby from exposure in breastmilk. Additionally, the ATA recommends stopping breastfeeding 6 weeks before starting I-131 treatment, to reduce the chance of radiation affecting breast tissue. Your healthcare providers can talk with you about what treatment is best for you. 

A breastfed child who is exposed to iodine-131 through milk could develop thyroid problems such as poor thyroid function, damage to the thyroid gland, and an increased chance of thyroid carcinoma.  

When possible, iodine-131 treatments and tests should wait until after the baby is weaned. In some cases, where only small amounts of radioiodine are used, it may be possible to resume breastfeeding when radioactivity counts return to base level. However, this may be several weeks. Be sure to talk to your healthcare providers about all your breastfeeding questions.  

If a man received iodine-131, could it affect his fertility or increase the chance of birth defects? 

Receiving iodine-131 can cause temporary fertility issues (ability to make healthy sperm) in males for up to 2 years after receiving treatment. No increase in birth defects has been found in children whose fathers were treated with iodine-131. 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/. 

Some people who receive iodine-131 treatment can release radiation for a short time after receiving treatment. Talk with your healthcare team about safety precautions for how you can reduce radiation exposure to other people, such as women who are pregnant and children. The length of time that you will need to follow these precautions will depend on your dose of I-131 among other factors. In general, people might need to follow safety precautions from 3 days to 2 weeks. The American Thyroid Association has an information sheet that includes this information at: https://www.thyroid.org/wp-content/uploads/patients/brochures/Radioactive_iodine_brochure.pdf.  

Please click here for references.  

This sheet is about exposure to clonidine 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 clonidine? 

Clonidine is a medication that has been used to treat high blood pressure, attention deficit hyperactivity disorder (ADHD), bipolar disorder, and pain. Some brand names include Catapres®, Duraclon®, and Kapvay®. Clonidine is sometimes used in combination with other medications for the management of opioid withdrawal.  

Sometimes when women 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 clonidine. Can it make it harder for me to get pregnant?  

It is not known if clonidine can make it harder to get pregnant. One study suggests the use of clonidine may increase the chance of pregnancy in women with polyendocrine metabolic ovarian syndrome (PMOS) (PMOS is the new name for polycystic ovary syndrome (PCOS).  

Does taking clonidine increase the chance of miscarriage?  

Miscarriage is common and can occur in any pregnancy for many different reasons. It is not known if clonidine can increase the chance of miscarriage.  

Does taking clonidine 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 clonidine, might increase the chance of birth defects in a pregnancy. The use of clonidine in pregnancy is not expected to increase the chance of birth defects. 

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

It is not known if clonidine can 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 [about 2,500 grams] at birth).  

One report that suggests that clonidine use might lead to a slower heart rate in the pregnant woman, leading to lower birth weight in the baby. In cases where clonidine was being used to treat high blood pressure, blood pressure issues might have played a role in the reduced weight of the baby.  

I need to take clonidine during my pregnancy. Will it cause withdrawal symptoms in my baby after birth?  

The use of clonidine during pregnancy can cause temporary symptoms in newborns soon after birth. These symptoms are sometimes referred to as withdrawal. Symptoms might include high or low blood pressure, drowsiness, and irritability. Most of the time the symptoms go away on their own, usually within a few weeks. Not all babies exposed to clonidine will have these symptoms. It is important that your healthcare providers know you are taking clonidine so that if symptoms happen, your baby can get the care that is best for them. 

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

It is not known if clonidine can increase the chance of behavior or learning issues in children. One older study noted that children exposed to clonidine during pregnancy showed higher rates of hyperactivity and sleep disturbances compared to a control group. Because clonidine is also used to treat conditions such as ADHD, if a child who was exposed to clonidine during pregnancy is later diagnosed with ADHD, it can be hard to determine whether this is related to the medication, to underlying familial or genetic issues, or other factors. 

Breastfeeding while taking clonidine: 

Clonidine passes into breastmilk in small amounts. There are case reports of infants exposed to clonidine through breast milk who did not have any reported side effects. There is 1 report that described a newborn baby who was drowsy, floppy (poor muscle control), had periods of not breathing, and possible seizure activity. These symptoms started soon after delivery and went away when breastfeeding was stopped, days after birth. It is not known if the symptoms were due to pregnancy exposure to clonidine, breastfeeding while taking clonidine, or other reasons. 

Taking clonidine might lower milk supply. If you notice your milk supply is lower than usual, talk with your baby’s pediatrician or a lactation consultant.  

If you suspect the baby has any symptoms (such as being more sleepy than usual, poor muscle control, breathing problems, or seizures) contact the child’s healthcare provider. Be sure to talk to your healthcare provider about all your breastfeeding questions.  

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

Trouble with getting and keeping an erection (impotence, a form of erectile dysfunction) has been reported in some men with high blood pressure being treated with clonidine. Also, one report suggests that clonidine may block or change the effects of the hormone progesterone on sperm. This can affect the ability to conceive a pregnancy. 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 for references.  

This sheet is about exposure to sarilumab 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 providers. 

What is sarilumab? 

Sarilumab is a medication that has been used for the treatment of rheumatoid arthritis (RA) and polymyalgia rheumatica (PMR). It has also been used to treat symptoms of severe COVID-19 in hospitalized patients. Sarilumab is a monoclonal antibody (a protein made by the body’s immune system) that binds and blocks interleukin-6 (IL-6), a protein that causes inflammation. A brand name for sarilumab is Kevzara®. For more information about RA and pregnancy, please see our fact sheet at https://mothertobaby.org/fact-sheets/rheumatoid-arthritis/. 

Sometimes when women 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 this 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 sarilumab. Can it make it harder for me to get pregnant?  

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

Does taking sarilumab increase the chance of miscarriage?  

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

Does taking sarilumab 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 sarilumab, might increase the chance of birth defects in a pregnancy. 

Studies have not been done to see if sarilumab increases the chance for birth defects above the background risk. There is a report of one woman using sarilumab during pregnancy and no birth defects were detected in the child. It is reassuring that sarilumab is not expected to cross the placenta and reach the pregnancy in large amounts during the first trimester, which is the time when a birth defect is most likely to happen.  

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

It is not known if sarilumab can increase the chance of pregnancy-related problems such as preterm delivery (birth before week 37 of pregnancy) or low birth weight (weighing less than 5 pounds, 8 ounces [about 2,500 grams] at birth). A small study that included one pregnancy exposed to sarilumab during treatment for COVID-19 suggested a higher risk of preterm delivery. However, COVID-19 is itself associated with preterm delivery, making it hard to know whether the observed risk was due to the infection or sarilumab exposure. 

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

Studies have not been done to see if sarilumab can increase the chance of behavior or learning issues for the child. There is a report of one woman using sarilumab during pregnancy and no problems were noted in the child at 6 months of age.  

Can my baby receive vaccines before one year of age if I take sarilumab later in pregnancy? 

Since sarilumab might suppress the immune system of the person taking it, there is a theoretical (not proven) concern that the same thing could happen to the baby if they are exposed during pregnancy. If a person has a weakened immune system, they may be more likely to develop an infection from a live vaccine. Live vaccines contain a small amount of live virus. Inactivated vaccines do not contain live virus, so they cannot cause the disease they protect against. In the United States, rotavirus is the only live vaccine routinely given in the first year of life. Most people can get inactivated vaccines in the first year of life.  

Talk with your child’s healthcare provider about your exposure to sarilumab during pregnancy. They can talk with you about the vaccines your child should receive and the best time for your child to receive them. 

Breastfeeding while taking sarilumab: 

There is very little information on the use of sarilumab during breastfeeding. Because sarilumab is a large protein, only small amounts are expected to pass into breast milk. In one study, a small amount of sarilumab was detected in breast milk. Any medication that enters the milk is likely to be broken down in the baby’s stomach and only minimally absorbed. Preterm infants and babies younger than 1 month of age may absorb more of the medication than older infants. Be sure to talk to your healthcare provider about all your breastfeeding questions.  

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

Studies have not been done to see if sarilumab can affect male fertility (ability to make healthy sperm) or increase the chance of birth defects. In general, exposures that fathers or sperm donors have are less likely 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 exposure to labetalol 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 providers. 

What is labetalol? 

Labetalol is a medication that has been used to treat high blood pressure and chest pain. Labetalol lowers blood pressure and improves blood flow by slowing the heart rate and opening blood vessels. Labetalol belongs to a group of medications called beta-blockers.  

Sometimes when women 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 labetalol. Can it make it harder for me to get pregnant? 

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

Does taking labetalol increase the chance of miscarriage?  

Miscarriage is common and can occur in any pregnancy for many different reasons. It is not known if labetalol can increase the chance of miscarriage. Having high blood pressure that is not well managed might increase the chance of miscarriage.     

Does taking labetalol 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 labetalol, might increase the chance of birth defects in a pregnancy. 

Information on the use of labetalol in pregnancy is limited. Available information does not suggest that the use of labetalol in pregnancy increases a higher chance of birth defects. 

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

Most studies do not suggest that labetalol 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), or stillbirth.  

Temporary symptoms starting shortly after birth have been reported in some infants who were exposed to labetalol late in the pregnancy. These symptoms include slowed heart rate, low blood pressure, and/or low blood sugar. In most cases, these symptoms go away within a few days. It has been suggested that infants who were exposed to labetalol during the pregnancy be monitored after birth; so that if symptoms occur, the baby can get the care that is best for them. 

There have also been cases in which infants exposed to beta-blockers during pregnancy had symptoms that started a week after birth. In these cases, the symptoms were more severe and life-threatening. The reported symptoms included abnormal breathing, sepsis (blood infection), and seizures. It has been suggested that preterm infants who were exposed to labetalol over a long period of time during pregnancy be carefully monitored during the first week after birth so that if symptoms occur, the baby can get the care that is best for them.   

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

It is not known if labetalol can increase the chance of behavior or learning issues for the child. One study of 32 children between the ages of 3 and 7 years old who were exposed to labetalol during pregnancy found no differences in formal testing of learning and behavior compared to children who were not exposed to labetalol. Another study suggested a higher chance of attention deficit hyperactivity disorder (ADHD) in children who were exposed to labetalol during pregnancy compared to children exposed to a different type of high blood pressure medication or no high blood pressure medication. However, the study had limitations that made it hard to know if labetalol played any role in the cases of ADHD.  

Breastfeeding while taking labetalol:           

Labetalol passes into breast milk in small amounts. These amounts are not expected to cause problems in full-term breastfed infants. If the baby was born preterm, discuss the risks and benefits of taking labetalol while breastfeeding with your healthcare provider and the child’s healthcare provider. If you suspect the baby has any symptoms such as drowsiness, looking pale, or not eating well, contact the child’s healthcare provider. Be sure to talk to your healthcare provider about all of your breastfeeding questions. 

If a male takes labetalol, could it affect his fertility or increase the chance of birth defects?   

There have been case reports of sexual dysfunction (trouble with ejaculation) in men while they were taking labetalol. This can make it harder to get a woman pregnant. Studies have not been done to see if labetalol could increase the chance of birth defects in a partner’s pregnancy. 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.