This sheet is about having a hantavirus in 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 are hantaviruses?

Hantaviruses are a group of viruses found around the world that can cause serious illness and sometimes death. Hantaviruses that are typically found in the Americas, including the Andes virus and Sin Nombre virus, can cause flu-like symptoms that can develop into hantavirus pulmonary syndrome (HPS), a severe lung disease. Hantaviruses that are more commonly found in Europe and Asia can cause hemorrhagic fever with renal syndrome (HFRS), which can damage blood vessels and kidneys.

The most common way to get a hantavirus is through direct contact with rodents. Wild mice and rats are the primary carriers, but the virus can also be spread by chipmunks, ground squirrels, gophers, and rodents kept as pets. People can get infected by touching rodent urine, droppings (poop), or saliva, or by breathing in contaminated air when these materials are stirred up. Less commonly, hantaviruses can spread through rodent bites and scratches. 

The Andes virus is the only hantavirus known to spread from person to person. This can happen through close contact with someone who is sick, such as direct physical contact, spending time together in close or enclosed spaces, or contact with the person’s body fluids. Infection can also happen by touching an object or surface with the virus on it, then touching your mouth, nose, or eyes.

What are the symptoms of hantavirus infection?

Symptoms of hantavirus infection usually start 1 to 8 weeks after exposure to the virus. Early symptoms can include fever, chills, muscle aches, headache, tiredness, dizziness, abdominal (stomach) pain, diarrhea, and/or vomiting. Four to 10 days later, people can start to experience symptoms of hantavirus pulmonary syndrome (HPS) that include cough, chest tightness, and trouble breathing. Symptoms of HPS can be severe and sometimes lead to death.

Symptoms of hemorrhagic fever with renal syndrome (HFRS) usually start 1 to 2 weeks after exposure to the virus, although symptoms might start as late as 8 weeks after exposure. Early symptoms of HFRS can include headache, fever, chills, back pain, abdominal (stomach) pain, nausea, and blurred vision. Sometimes, people can have flushing (redness) of the face, red eyes, and rash. Later symptoms of HFRS can include low blood pressure, problems with blood flow, internal bleeding, and kidney failure. In some cases, HFRS can cause death.

In pregnancy, symptoms and outcomes of hantavirus infection can vary depending on the specific hantavirus. Although information is limited, pregnant women might be more likely to experience worse symptoms and have poorer outcomes (like severe disease and death) from a hantavirus infection compared to women who are not pregnant. Since hantavirus can cause serious illness, women who are pregnant and have hantavirus should receive medical care right away. Symptoms of hantavirus can be treated, but there is no vaccine or cure for HPS or HFRS.

How can I protect my pregnancy from hantaviruses?

Women who are pregnant should avoid contact with rodents and their urine, droppings, and nesting materials. This includes pet rodents like mice, rats, and hamsters. If there are mice or rats in the home (pests), it is important to have the home treated and to safely clean up any droppings or bedding. CDC has helpful tips about rodent control and cleanup here: https://www.cdc.gov/healthy-pets/rodent-control/clean-up.html.

CDC also has tips to lower the chance of infection if someone around you has the Andes virus. These include washing hands often, not sharing drinks, cigarettes, or utensils (like forks or spoons), keeping physical distance from the infected person, avoiding kissing, and not having sex with them. More information is available here: https://www.cdc.gov/hantavirus/about/andesvirus.html.

How can I find out if I am infected with a hantavirus?

A blood test can be done to see if a person is infected with a hantavirus. The test might not be able to detect the virus during the first 72 hours (3 days) of infection. Repeating the blood test 72 hours after symptoms begin is often recommended. If you suspect a hantavirus infection, talk with a healthcare provider immediately and mention any possible exposure to rodents.

I have a hantavirus. Can it make it harder for me to get pregnant?

It is not known if having a hantavirus can make it harder to get pregnant. Hantavirus infection can be very serious and may temporarily affect overall health and reproductive health during recovery. Because hantavirus can affect the lungs, kidneys, and other organs, it is important to talk with a healthcare provider before trying to get pregnant, especially if the illness was recent or severe.

Does having a hantavirus 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 hantaviruses can increase the chance of miscarriage.

Does having a hantavirus 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 a hantavirus, might increase the chance of birth defects in a pregnancy. It is not known if hantaviruses can increase the chance of birth defects. 

Fever is a possible symptom of HPS and HFRS. A high fever in the first trimester can increase the chance of certain birth defects. Acetaminophen has been recommended to reduce fever in pregnancy. If you get sick with a hantavirus or any other illness and develop a fever, talk with your healthcare provider to confirm if taking acetaminophen is okay for you. For more information about fever and pregnancy, see the MotherToBaby fact sheet about hyperthermia at https://mothertobaby.org/fact-sheets/hyperthermia-pregnancy/.

Does having a hantavirus increase the chance of other pregnancy related problems?

It is not known if hantaviruses can cause other pregnancy-related problems, such as preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2,500 grams] at birth). There are case reports of preterm birth and fetal death following hantavirus infection in pregnancy. 

One case report suggested that a hantavirus might have passed from a woman to her fetus during pregnancy (called vertical transmission). However, since the infant was not tested until 15 days after delivery, it is possible that the baby was infected after birth and not during the pregnancy. No vertical transmission of hantavirus was reported in 12 other case reports.

Does having a hantavirus in pregnancy affect future behavior or learning for the child?

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

Breastfeeding while I have a hantavirus:

There is limited information about hantaviruses and breastfeeding. One case report described a baby who became infected with hantavirus after being breastfed by a woman with HPS. The virus was found in the woman’s breast milk, although other sources of infection for the baby could not be ruled out. Since some hantaviruses can spread through close contact and body fluids, women who are infected while breastfeeding should take precautions (such as limiting close contact) to not spread the virus to the nursing baby and others. 

It is important to check in regularly with a pediatrician and healthcare team for updated guidance while breastfeeding during or after a hantavirus infection. Be sure to talk to your healthcare provider about all your breastfeeding questions. 

If a man has a hantavirus, can it affect his fertility or increase the chance of birth defects?

Studies have not been done to see if hantaviruses could affect men’s fertility (ability to make healthy sperm) or increase the chance of birth defects. Since some hantaviruses may be passed from person to person through close contact including sexual intercourse, infected men should take precautions to not spread the virus to a pregnant partner. 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 hydroxychloroquine 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 hydroxychloroquine? 

Hydroxychloroquine is a medication that has been used to prevent and treat malaria and to treat autoimmune conditions, including rheumatoid arthritis and lupus. Plaquenil® is a brand name for hydroxychloroquine. For more information on malaria, rheumatoid arthritis, and lupus, please see the MotherToBaby fact sheets at https://mothertobaby.org/fact-sheets/malaria/, https://mothertobaby.org/fact-sheets/rheumatoid-arthritis/, https://mothertobaby.org/fact-sheets/lupus-pregnancy/.  

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.  

The Society for Maternal Fetal Medicine (SMFM) has recommended that women who are pregnant and have lupus should continue or start hydroxychloroquine. For women with lupus but no current symptoms or treatment, the SMFM has recommended talking with their healthcare providers regarding the benefits and limitations of starting or not starting this medication during pregnancy. 

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

Studies have not been done to see if taking hydroxychloroquine can make it harder to get pregnant. However, hydroxychloroquine might improve the success rates of certain fertility treatments. 

Does taking hydroxychloroquine increase the chance of miscarriage? 

Miscarriage is common and can occur in any pregnancy for many different reasons. Several studies have not found a higher chance of miscarriage related to hydroxychloroquine use. One study reported a higher number of miscarriages than expected, but the authors stated that the mother’s health conditions may have contributed to this finding since malaria and lupus can increase the chance of miscarriage. 

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

Most studies looking at the use of hydroxychloroquine to treat rheumatic disease in pregnancy have not found an increased chance of birth defects.  

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

Studies do not suggest that hydroxychloroquine increases 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). Having malaria or lupus in pregnancy might increase the chance of preterm delivery.  

When a woman who is pregnant has lupus, it can lead to symptoms of lupus in the baby (called neonatal lupus). The most serious complication of neonatal lupus is a heart rhythm problem called congenital heart block. Hydroxychloroquine might reduce the chance of congenital heart block in pregnancies that are at an increased risk for this condition.  

Damage to the inner lining of the eye (called retinopathy) is an uncommon side effect of taking hydroxychloroquine. This has raised a theoretical (not proven) concern that taking hydroxychloroquine in pregnancy could cause vision problems in the offspring. However, most studies on young children born to women who took hydroxychloroquine in pregnancy have not found an increase in eye problems.  

Does taking hydroxychloroquine affect future behavior or learning for the child? 

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

Breastfeeding while taking hydroxychloroquine: 

Hydroxychloroquine passes into breast milk in small amounts. Studies on hydroxychloroquine in breastfeeding have reported no harmful effects on infants, including no effects on vision, hearing, or growth problems in children who were followed up to about 1 year of age. Be sure to talk to your healthcare provider about all your breastfeeding questions. 

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

A review of studies on men who used medications to treat rheumatic disease at or near the time of conception did not find that hydroxychloroquine affected fertility (ability to make healthy sperm) or pregnancy outcomes. 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 autoimmune diseases and the medications used to treat autoimmune diseases. If you are interested in learning more, please call 1-877-311-8972 or visit https://mothertobaby.org/join-study/. 

Please click here for references. 

 

This sheet is about exposure to vitamin B12 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 vitamin B12?

Vitamin B12 is an essential vitamin that is used by the body to keep your nerve and blood cells healthy and to help make DNA (genetic material created in your body). Essential vitamins are nutrients that the body cannot make, so people need to get them from other sources. Vitamin B12 can be found in animal products including meat, seafood, eggs, and dairy products. Cereals and nutritional yeast have vitamin B12 added to them. Vitamin B12 is also available as a dietary supplement, or as a prescription medication in the form of an injection (shot) or nasal spray. Vitamin B12 has also been called cobalamin.  

Vitamin B12 deficiency (not having enough vitamin B12 in the body) can cause fatigue (feeling very tired), muscle weakness, pale or ashy skin, a racing heart, loss of appetite, weight loss, and numbness or tingling in the hands and feet. Not all people with a vitamin B12 deficiency will have symptoms. Sometimes, other health conditions or taking medications that interact with how vitamin B12 is absorbed can increase the chance of having symptoms.  

If your healthcare provider has recommended taking vitamin B12, talk with them before making changes to how you take this supplement Your healthcare providers can talk with you about the benefits of maintaining your nutrient levels and the risks of low vitamin B12 during pregnancy. 

Talk with your healthcare providers about all of the supplements and vitamins that you take. Have the bottles or photos of the labels with you so that all reported ingredients and their amounts can be reviewed.  

How much vitamin B12 is needed in pregnancy?

The Recommended Dietary Allowance (RDA) is the average daily level of intake that is enough to meet the nutrient needs for most people. The Tolerable Upper Intake Level (UL) is the dose that people can start to have side effects. It is not recommended to take more than the RDA of vitamin B12 unless you are doing so under the care of your healthcare provider to treat a condition. There is currently no UL for vitamin B12, because vitamin B12 is not stored in the body in excess (extra) amounts. The RDA for females who are pregnant is 2.6 mcg of vitamin B12 a day.  

Most people get enough vitamin B12 from their diet. When adding up how much vitamin B12 you are getting, remember to count amounts from foods, drinks, and from any supplements you are taking. There are resources available online that list amounts of vitamin B12 typically found in foods, such as the United States Department of Agriculture (USDA) National Nutrient Database, found here: https://www.nal.usda.gov/sites/default/files/page-files/Vitamin%20B-12.pdf. Diet, medications, and certain medical conditions can cause someone to have low levels of vitamin B12. Some people might need to take a vitamin B12 supplement. Be sure to talk with your healthcare providers about your specific nutritional needs before, during, and after pregnancy. 

Can vitamin B12 make it harder for me to get pregnant? 

Taking vitamin B12 at the RDA is not expected to make it harder to get pregnant. It is not known if having a vitamin B12 deficiency can make it harder to get pregnant.  

Does vitamin B12 increase the chance of miscarriage? 

Miscarriage is common and can occur in any pregnancy for many different reasons. Taking vitamin B12 at the RDA is not expected to increase the chance of miscarriage. Some studies reported that having low levels of vitamin B12 (less than 200-300 pg/mL in blood) was associated with an increased chance of miscarriage. Some of these studies combined multiple factors together, including other vitamins. As there can be many causes of miscarriage, it is hard to know if vitamin levels, health conditions, or other factors are the cause of a miscarriage.  

Does vitamin B12 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 vitamin B12, might increase the chance of birth defects in a pregnancy. Taking vitamin B12 at the RDA is not expected to increase the chance of birth defects.  

It is not known if having too little vitamin B12 can increase the chance of birth defects. Some studies report that having too little vitamin B12, or having lower metabolism (the body’s processing) of vitamin B12 can increase the chance of neural tube defects (an opening in the spine or skull). Other studies have not reported the same results. Two studies have reported an increased chance of cleft lip and/or palate (an opening in the upper lip or the roof of the mouth) in babies born to women who were deficient in B12 during pregnancy.  

Does vitamin B12 increase the chance of other pregnancy-related problems?

Taking vitamin B12 at the RDA 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).  

Having a vitamin B12 deficiency (B12 levels below 148mol/L) or low vitamin B12 has been associated with preterm delivery. One study did not report an association between low or deficient vitamin B12 levels and birth weight.   

Does vitamin B12 affect future behavior or learning for the child?  

Taking vitamin B12 at the RDA is not expected to affect future behavior or learning for the child. It is not known if having a vitamin B deficiency can affect future behavior or learning for the child.  

Breastfeeding and vitamin B12:

Vitamin B12 is a typical part of breast milk. If you are breastfeeding, continue to get the daily recommended daily allowance of vitamin B12 unless otherwise directed by a healthcare provider. The RDA for females who are breastfeeding is 2.8 mcg of vitamin B12 a day.  

If a person who is breastfeeding is deficient in vitamin B12, the child may have an increased chance of having vitamin B12 deficiency if they are exclusively breastfed. Infants who are vitamin B12 deficient might experience low muscle tone, uncontrolled movements (tremors), anemia, and changes in skin and hair development.  

Getting enough vitamin B12 while breastfeeding can help a child get enough vitamin B12. See the chart above to find the RDA for vitamin B12 for women who are breastfeeding. Also, talk to your healthcare provider and your baby’s pediatrician about your specific nutritional needs before, during, and after breastfeeding. Be sure to talk to your healthcare provider about all your breastfeeding questions.  

Does vitamin B12 affect fertility or increase the chance of birth defects?

Taking vitamin B12 at the RDA is not expected to affect men’s fertility (ability to get a partner pregnant) or increase the chance of birth defects. Studies have not been done in humans to see if a vitamin B12 deficiency could affect men’s fertility 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 exposure to methimazole in pregnancy and while breastfeeding. This information is based on available published literature. It should not take the place of medical care and advice from your healthcare provider.

What is methimazole?

Methimazole is a medication that has been used to treat hyperthyroidism (when the thyroid gland makes too much thyroid hormone) and Graves’ disease (a common cause of hyperthyroidism). Methimazole lowers the amount of thyroid hormone that the thyroid gland makes. Tapazole® was a brand name for methimazole.

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. Untreated hyperthyroidism can increase the chance of illness for the pregnant woman and the chance of pregnancy complications. Your healthcare providers can talk with you about the benefits of treating your condition and the risks of untreated illness during pregnancy.

The US Food and Drug Administration (FDA), The American College of Obstetricians and Gynecologists (ACOG), and The American Thyroid Association (ATA) have stated that propylthiouracil (PTU), another medication that has been used to treat hyperthyroidism, might be the preferred treatment for hyperthyroidism during the first trimester of pregnancy. MotherToBaby has a fact sheet on PTU here: https://mothertobaby.org/fact-sheets/propylthiouracil-ptu/.

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

Studies have not been done to see if methimazole can make it harder to get pregnant. Untreated thyroid disorders can make it harder to get pregnant.

Does taking methimazole increase the chance for miscarriage?

Miscarriage is common and can occur in any pregnancy for many different reasons. One study did not find an increased chance of miscarriage in 241 women who were pregnant and used methimazole in early pregnancy. Hyperthyroidism has been associated with an increase in the chance for miscarriage.

Does taking methimazole 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 methimazole, might increase the chance of birth defects in a pregnancy. Some studies and case reports suggest there could be an increased chance of birth defects when taking methimazole. There has been a suggested pattern of birth defects linked to methimazole exposure. The most commonly reported findings include aplasia cutis (ulcers on the scalp), choanal atresia (narrowing in the opening to the nasal passages), and esophageal atresia (tube connecting mouth to stomach is not formed properly). There are also studies and case reports that did not find an increase in the chance of birth defects when methimazole is taken in pregnancy. Some studies suggest that the underlying medical condition (hyperthyroidism), may play a role in the chance for birth defects. In summary, there is not enough evidence to suggest that taking methimazole clearly increases the chance of birth defects above the background chance.

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

One study found a higher chance of preterm delivery (birth before week 37) and low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth) when methimazole was used during pregnancy. Hyperthyroidism has also been found to increase the chance for preterm delivery, smaller size (small for gestational age), and low birth weight.

Taking medications to lower thyroid levels, like methimazole, or having Graves’ disease in pregnancy can lead to thyroid levels that are either too low or too high in the fetus. If you take methimazole or if you have Graves’ disease, let your baby’s healthcare providers know, so that they can check your baby’s thyroid level after delivery.

The FDA has reported that methimazole can cause liver damage and or serious life-threatening decreases in white blood cells in people who take this medication, including pregnant women. There is limited information on whether methimazole use during pregnancy can cause liver damage or a decrease in white blood cells in the fetus.

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

Three studies looking at 56 children (from preschool to adult ages) exposed to methimazole during pregnancy found no difference in intelligence scores compared to their unexposed brothers or sisters or other unexposed people. Untreated thyroid disorders in pregnancy can increase the chance of learning problems in children.

Breastfeeding while taking methimazole:

Methimazole gets into breast milk. In 3 case series including 56 infants, and 1 study including 51 infants, methimazole in doses up to 20mg per day did not affect the breastfed infants’ thyroid function or intellectual development. Be sure to talk to your healthcare provider about all your breastfeeding questions.

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

Studies have not been done to see if methimazole could affect a man’s fertility (ability to get a woman pregnant) or increase the chance of birth defects above the background risk. 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 sulfamethoxazole-trimethoprim 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 sulfamethoxazole-trimethoprim (SMZ-TMP)? 

Sulfamethoxazole and trimethoprim (SMZ-TMP) are two medications that have been used together to treat bacterial infections, including urinary tract infections (UTIs). They belong to a class of medications known as sulfonamide antibiotics. The SMZ-TMP combination is sold under the brand names Bactrim®, Septra®, or Sulfatrim®.  

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. 

The American College of Obstetricians and Gynecologists (ACOG) states that SMZ-TMP can be used in the first trimester if no acceptable alternatives are available, and that SMZ-TMP can be considered a first-line treatment for UTIs in the second and third trimester. Your healthcare provider can talk with you about using sulfamethoxazole-trimethoprim and what treatment is best for you. 

I take SMZ-TMP. Can it make it harder for me to get pregnant?

It is not known if SMZ-TMP can make it harder to get pregnant.  

Does taking SMZ-TMP increase the chance of miscarriage?

Miscarriage is common and can occur in any pregnancy for many different reasons. Two studies reported an increased chance of miscarriage with the use of SMZ-TMP in the first trimester. However, one of these studies did not look at other factors that might have contributed to the results. As there can be many causes of miscarriage, it is hard to know if a medication, the condition being treated, or other factors are the cause of a miscarriage. 

Does taking SMZ-TMP 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 SMZ-TMP, might increase the chance of birth defects in a pregnancy.  

It is not known if taking SMZ-TMP can increase the chance of birth defects. A few studies have reported an increased chance of birth defects such as heart defects, neural tube defects (defects of the brain and spinal cord), cleft lip and/or palate (opening in the top lip and/or the roof of the mouth), and urinary tract defects. However, these studies did not control for other factors that could have affected the results. Also, other studies have not shown an increased chance of birth defects with SMZ-TMP use in the first trimester.  

Trimethoprim might lower the level of folic acid in the body. Folic acid is a B vitamin that helps the body make new healthy cells and, when taken at specific doses, can help reduce the chance of certain birth defects, such as spina bifida, in the baby. It is recommended that people who are pregnant or planning a pregnancy consume between 400-800 micrograms of folic acid each day from foods or vitamin supplements. If SMZ-TMP is taken during the first trimester, your healthcare provider might suggest that you take more folic acid. Talk with your healthcare provider about how much folic acid is right for you. For more information on folic acid, see the MotherToBaby fact sheet at https://mothertobaby.org/fact-sheets/folic-acid/.  

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

Some studies suggest taking SMZ-TMP might increase the chance of preterm delivery (birth before week 37), low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth), and the baby being small for gestational age (smaller in size compared to babies of the same age). However, this medication is often used to treat UTIs, and people who are pregnant with UTIs have a greater chance for some of the same complications. This makes it hard to know if it is the medication, the condition being treated, or other factors that can increase the chance for these complications.  

Some authors have recommended not taking sulfonamides such as sulfamethoxazole after 32 weeks of pregnancy. There is a theoretical concern (not proven) that sulfonamide use near the end of pregnancy can increase the chance for severe jaundice (a buildup of bilirubin in the blood that makes the eyes and skin look yellow) and other related complications in the baby. Talk with your healthcare provider about your condition and the treatment that is right for you. 

Does taking SMZ-TMP in pregnancy affect future behavior or learning for the child?

Studies have not been done to see if SMZ-TMP can increase the chance of behavior or learning issues for the child. 

Breastfeeding while taking SMZ-TMP:

SMZ-TMP gets into breast milk in small amounts. Of 12 people who took SMZ-TMP during breastfeeding, two reported poor feeding in their infants. No other side effects were reported. If you suspect the baby has any symptoms (such as poor feeding) contact your child’s healthcare provider.  

If the baby is born before 37 weeks of pregnancy, has severe jaundice, or glucose-6-phosphate dehydrogenase (G6PD) deficiency (an uncommon genetic condition in which the liver does not break down red blood cells properly), talk with your healthcare provider and your baby’s pediatrician about using SMZ-TMP and breastfeeding. While some people in these situations might need to stop breastfeeding while taking SMZ-TMP, it is not always necessary. Be sure to talk to your healthcare provider about all your breastfeeding questions. 

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

The use of SMZ-TMP was found to lower the amount of sperm that men made after they took the medication for one month. This could affect fertility (ability to get a partner pregnant). Studies have not been done to see if a man’s exposure to SMZ-TMP 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/. 

Please click here for references.