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.     

This sheet is about exposure to St. John’s wort 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 St. John’s wort? 

St. John’s wort (Hypericum perforatum) is a flowering plant that has been used as an herbal supplement. It is available as a tablet or capsule, liquid extract, tea, and as a cream or ointment. It is also sometimes mixed with other herbal ingredients in combination products. St. John’s wort has most commonly been used to help symptoms of mild to moderate depression. MotherToBaby has a fact sheet on depression at: https://mothertobaby.org/fact-sheets/depression-pregnancy/.  

There are many compounds in St. John’s wort. The amount and quality of these compounds can vary widely and be affected by the soil the plant was grown in, and how the plant was harvested, dried, and stored. St. John’s wort can interact with many medications (change how well they work in the body or cause side effects), including birth control pills. If you are taking any medication, talk to your healthcare providers to review the chance of interactions between your medication and St. John’s wort.  

In the United States, St. John’s wort is a dietary supplement. Unlike prescription medication, dietary supplements are not regulated by the Food and Drug Administration (FDA) in the same way and do not have set standards for preparation, safety, or effectiveness. For information on supplements in general, please see the fact sheet on herbal products at https://mothertobaby.org/fact-sheets/herbal-products-pregnancy/. 

Sometimes when women find out they are pregnant, they think about changing how they take supplements or their medication. It is important to talk with your healthcare providers before making changes in how you take your medication or supplements. Your healthcare providers can talk with you about the benefits of treating your condition and the risks of untreated illness during pregnancy. Your healthcare team might discuss medication options that have been better studied for use in pregnancy. 

I take St. John’s wort. Can it make it harder for me to get pregnant?  

It is not known if St. John’s wort can make it harder to get pregnant. 

Does taking St. John’s wort increase the chance of miscarriage?  

Miscarriage is common and can occur in any pregnancy for many different reasons. It is not known if St. John’s wort can increase the chance of miscarriage. One study found the chance for a miscarriage in women taking St. John’s wort during pregnancy to be similar to the general population’s chance for miscarriage. 

Does taking St. John’s wort 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 St. John’s wort, might increase the chance of birth defects in a pregnancy. St. John’s wort has not been well-studied with use in pregnancy. Three studies that looked at pregnancies with use of St. John’s wort did not report an increase in birth defects.  

Does taking St. John’s wort in pregnancy increase the chance of other pregnancy-related problems? 

A study that included 39 women who reported using St. John’s wort early in their pregnancies did not find a higher chance for preterm delivery (delivery before 37 weeks of pregnancy) or poor growth in the babies. A second study of 54 infants prenatally exposed to St. John’s wort found a similar rate of live birth and preterm delivery when compared to babies not exposed to St. John’s wort. There is one case report of a woman who started taking St. John’s wort at week 24 of pregnancy and developed thrombocytopenia but had a normal delivery. Thrombocytopenia is a condition where the blood does not have enough platelets (cells that help your blood to clot). Some reports suggest that St. John’s wort can affect how a person’s blood clots. It is not known if the low platelet count in this case report was related to St. John’s wort or another factor. 

Does taking St. John’s wort in pregnancy affect future behavior or learning for the child?   

Studies have not been done to see if St. John’s wort can increase the chance of behavior or learning issues for the child.   

Breastfeeding while taking St. John’s wort: 

St. John’s wort gets into breastmilk. In 5 women who were breastfeeding full-term older infants (10-22 weeks of age), the amount of St. John’s wort that the infants received through breastmilk was found to be small. The parents reported no negative effects in their infants. Another study that looked at 33 women who took St. John’s wort and breastfed reported an increased amount of crying (colic) and being very sleepy (lethargy) in their infants when compared to infants of women with depression who were not taking St. John’s wort. The infants did not need medical treatment. If you suspect the baby has any symptoms from the St. John’s wort such as colic, drowsiness, or poor feeding, contact the child’s healthcare provider. Be sure to talk to your healthcare provider about all of your breastfeeding questions. 

If a male takes St. John’s wort, could it affect his fertility or increase the chance of birth defects? 

St. John’s wort has not been well studied to see how it might affect male fertility (ability to make healthy sperm) or increase the chance of birth defects above the background risk. There are case reports of sexual difficulties (reduced desire or ability to perform) in men taking St. John’s wort; similar things were reported in laboratory animal studies.  Experimental laboratory data have suggested that St. John’s wort might have spermicidal effects (kill sperm or reduce ability to swim towards the egg). 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 salmeterol in a 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 salmeterol? 

Salmeterol (Serevent®, Serevent Diskus®) is a medication that has been used to treat asthma, chronic obstructive pulmonary disease (COPD), and also as prophylaxis for exercise induced bronchospasm. It is in a class of medications called beta2-agonists. Beta2-agonists help to open the airways in the lungs (bronchodilators). Salmeterol is a long-acting beta2-agonist taken by breathing it into the lungs (inhalation). It is used together with an inhaled corticosteroid to treat asthma. For information on inhaled corticosteroids, see the MotherToBaby fact sheet at https://mothertobaby.org/fact-sheets/inhaled-corticosteroids-icss-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. 

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

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

Does taking salmeterol 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 salmeterol can increase the chance of miscarriage.  

Does taking salmeterol 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 salmeterol, might increase the chance of birth defects in a pregnancy. A small number of studies do not suggest an increased chance of birth defects with the use of inhaled salmeterol during pregnancy. When salmeterol is inhaled, very little of the drug gets into the blood. Even less of the medication is expected to reach the developing fetus. 

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

Small studies have not suggested higher rates of preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth) with the use of salmeterol during pregnancy. Asthma that is not well controlled can increase the chance of pregnancy complications. For information on asthma, see the MotherToBaby fact sheet at https://mothertobaby.org/fact-sheets/asthma-and-pregnancy/.  

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

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

Breastfeeding while taking salmeterol: 

Studies have not been done to look at the use of salmeterol during breastfeeding. When salmeterol is inhaled, very little of the drug gets into the blood and it is not expected to pass into breastmilk in large amounts. Using inhaled bronchodilators is usually compatible with breastfeeding. Be sure to talk to your healthcare provider about all your breastfeeding questions. 

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

Studies have not been done to see if salmeterol could affect male fertility (ability to get a woman pregnant) or increase the chance of birth defects. When salmeterol is inhaled, very little of the drug gets into the blood, so effects on fertility or pregnancy are not expected. 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 penicillin G 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 penicillin G?

Penicillin G is an antibiotic drug that belongs to a class of antibiotic medications called penicillins. It works by killing bacteria that cause infections and has been used to treat Staphylococcus aureus (Staph) and syphilis. Penicillin G is given intravenously, sometimes called “I.V.”. This involves injecting the medication into a vein.

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.

It is important to treat infections in pregnancy. Some infections, such as Staph or syphilis, can increase the chance of pregnancy-related problems or infections in a newborn baby if not properly treated during pregnancy. Syphilis can also be passed to a fetus during any trimester of pregnancy, which can cause health problems in the newborn. MotherToBaby has fact sheets on Staph here: https://mothertobaby.org/fact-sheets/staphylococcus-aureus-pregnancy/ and syphilis here: https://mothertobaby.org/fact-sheets/syphilis/.

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

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

Does taking penicillin G increase the chance of miscarriage?

Miscarriage is common and can occur in any pregnancy for many different reasons. Taking penicillin G in pregnancy is not expected to increase the chance of miscarriage.

Does taking penicillin G increase the chance of birth defects?

Every pregnancy starts out with a 3-5% chance of having a birth defect. This is called the background risk. Multiple studies have looked at the use of penicillin G during pregnancy and have not reported an increased chance of birth defects.

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

Penicillin G is not expected to cause 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).

Some people are allergic to penicillins. In very rare cases, penicillin G can cause anaphylaxis (severe allergic reaction where the body goes into shock). Anaphylaxis can cause trouble breathing, low blood pressure, dizziness or fainting, and nausea. Severe or uncontrolled anaphylaxis can affect blood flow to the fetus, which could affect the growth and development of the fetus. If you think you are allergic to penicillin, talk with your healthcare provider about this and the best way to treat your condition.

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

Information from limited studies does not suggest that taking penicillin G during pregnancy can increase the chance of behavior or learning issues for the child.

Breastfeeding while taking penicillin G:

Limited information suggests that the amount of penicillin G that gets into breast milk is small. Taking penicillin G is not expected to cause side effects in most infants. Babies who are exposed to penicillins through breast milk might have diarrhea or develop thrush (fungal infection in the mouth). If you suspect the baby has any symptoms (such as diarrhea, white spots in the mouth, or mouth pain), contact the child’s healthcare provider. Be sure to talk to your healthcare provider about all your breastfeeding questions.

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

If you are taking penicillin G for an infection that can be transmitted to others by sexual contact (such as syphilis), it is important to treat your infection for your own health and for your partner’s health. Passing infections on to a woman who is pregnant might increase risks to a pregnancy. Your healthcare provider can talk with you about what steps can be taken to help prevent sexual transmission of infections to your partner.

Studies have not been done to see if penicillin G 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 phentermine 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 phentermine?

Phentermine is a medication that has been used as an appetite suppressant to treat obesity. Some brand names for phentermine are Adipex®, Fastin®, Ionamin®, Lomaira™®, or Zantryl®. The combination of phentermine and topiramate is sold under the brand name Qsymia®. MotherToBaby has a fact sheet on topiramate here: https://mothertobaby.org/fact-sheets/topiramate/.  

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. 

The product labels for phentermine and the combination of phentermine and topiramate recommend women who are pregnant not use these medications. However, the benefit of using phentermine in a pregnancy may outweigh possible risks. Your healthcare providers can talk with you about using phentermine and what treatment is best for you.  

Obesity can make it harder to get pregnant, and increase the chance of miscarriage, birth defects, or other pregnancy complications. MotherToBaby has a fact sheet on obesity here: https://mothertobaby.org/fact-sheets/obesity-pregnancy/.  

I am taking phentermine, but I would like to stop taking it before becoming pregnant. 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 non-pregnant adults, it takes up to 8 days, on average, for most of the phentermine to be gone from the body.   

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

Studies have not been done to see if taking phentermine can make it harder to get pregnant. 

Does taking phentermine 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 phentermine can increase the chance of miscarriage. 

Does taking phentermine 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 phentermine, might increase the chance of birth defects in a pregnancy. There is little information on phentermine exposures during early pregnancy. The available data does not suggest an increased chance of birth defects.  

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

Studies have not been done to see if phentermine 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). 

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

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

Breastfeeding while taking phentermine:

Studies have not been done on the use of phentermine while breastfeeding. The product labels for phentermine and the combination of phentermine and topiramate recommend women who are breastfeeding not use these medications. But the benefits of using phentermine might outweigh possible risks. Your healthcare providers can talk with you about using phentermine and what treatment is best for you. Be sure to talk to your healthcare provider about all your breastfeeding questions.  

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

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

Please click here for references.