Tenofovir disoproxil fumarate (TDF) (Viread ®)

Last Update: 03 Sep 2026

Table of content

1. What Is It? 2. Risks 3. Benefits 4. Lactation 5. Key Takeaways 6. Research limits

Welcome to our Fact Sheet on TDF during pregnancy and lactation. The information given is based on current research and may be updated with new scientific knowledge. This information does not replace personalized advice from healthcare professionals.

The Healthy Pregnancy Hub collaborates with the expertise of the CIHR Pan-Canadian Network for HIV and STBBI Clinical Trials (CTN+) in developing this information sheet.

CTN+ plays a central role in Canada’s response to HIV and other sexually transmitted and blood-borne infections (STBBIs). Through high-quality research conducted in partnership with communities, the network helps develop evidence-based solutions for people and regions affected by these infections.

1. What is Tenofovir disoproxil fumarate?

Tenofovir disoproxil fumarate (TDF) (Viread®) belongs to a group of medications called nucleotide analog reverse transcriptase inhibitor (NRTI). TDF comes as a tablet that can be used in different ways:

To treat human immunodeficiency virus (HIV) used together with other HIV medications as part of a treatment called antiretroviral therapy (ART).
To treat hepatitis B (HBV) is usually taken on its own.
To prevent HIV: TDF can be used with another medication called emtricitabine. This is called pre-exposure prophylaxis (PrEP). It may be offered to people who have a higher chance of getting HIV, including during pregnancy to reduce the chances of passing HIV.

TDF works by blocking an important step that viruses need to make more copies of themselves. This helps lower the amount of virus in the body (viral load). For people living with HIV, treatment can lower the viral load to an undetectable level. Keeping HIV well controlled helps protect your health and greatly reduces the chance of passing HIV to a partner or baby during pregnancy, birth, or lactation. For people living with hepatitis B, TDF can also reduce the chance of passing the virus to the baby.

TDF is recommended in clinical guidelines as a first-choice treatment option during pregnancy. If you are pregnant or planning a pregnancy, talk to your healthcare provider before starting, stopping, or changing any medication. Taking your medication as prescribed is important, as missing doses can make the treatment less effective. During pregnancy, your healthcare team may also do blood tests to make sure the treatment is working well.

2. What are the risks of TDF during pregnancy?

There’s no perfectly risk-free option when it comes to medication during pregnancy. If you are pregnant or planning a pregnancy, talk to your healthcare provider before starting, stopping, or changing any medication, including TDF.

Because TDF has been used and studied in many pregnancies around the world, it is considered one of the best-studied options during pregnancy. Large studies and international monitoring programs have shown it is effective and safe to use when needed. If you have questions about what these studies mean for you, your healthcare professional can help you understand the possible benefits and risks based on your own situation.

Understanding risks during pregnancy

Every pregnancy starts with some risks. Problems like miscarriage (loss of the baby), birth defects (malformations present at birth), or premature birth (before 37 weeks) can happen in any pregnancy for many reasons. This is called the background risk. When researchers study a medication like TDF, they compare pregnancy outcomes in people taking TDF with those in people taking other treatments or with general population rates.

TDF is one of the most studied antiviral medications in pregnancy, both for HIV and hepatitis B. Overall, the research is reassuring.

Most studies do not show a higher risk of major malformations. The rate of congenital malformations was also similar whether TDF was taken in the first trimester or later in pregnancy.
Research has not found a clear increase in risks like low birth weight or babies being smaller than expected.
Some studies have looked at growth and preterm birth, but results have been mixed.
Studies in pregnant people living with hepatitis B have also been reassuring. In three clinical trials, pregnant people who took TDF later in pregnancy did not have more pregnancy-related complications than expected, and no new safety concerns were found in the infants after birth.

The table below summarises what research has found so far. These are comparisons, and your personal risk may be different. Other factors like your health, other medications, and the infection being treated can also affect pregnancy outcomes.

Table 1. Possible risks associated with taking TDF during pregnancy.

Who?	What?	What does research say?
Pregnant person	Fertility (ability to get pregnant)	Human studies do not give a clear answer. One study in women living with HIV found a slightly lower pregnancy rate in people taking TDF, while another study in women using TDF/FTC for prevention did not find a difference. More research is needed.
Pregnant person	Miscarriages	Large pregnancy registry with over 30,000 pregnancies have not found an increased risk of miscarriage with TDF compared with the other HIV medications tooltip .
Unborn child	Congenital Malformations	Studies are reassuring. First-trimester TDF exposure has not been linked with a higher risk of major birth defects. Birth defect rates were similar to the background rate (about 3 out of every 100 pregnancies) whether TDF was started early or later in pregnancy tooltip .
	Growth	Few studies have not found a clear increased risk to have low birth defect or baby being smaller than expected compared to people taking other HIV medications tooltip . More studies are needed to better understand if there’s a risk.
	Premature Birth	Findings are mixed, some studies found a possible link with preterm birth, while others did not tooltip . More studies are needed.
Child later in life	Brain development	More studies are needing to evaluate this risk.
Child later in life	Long-term health issues	Some studies have observed a difference in growth during the first year of life, but the long-term meaning of these findings is still uncertain. More research is needed.
Fathers and sperm donors	Male’s fertility and pregnancy complications	One study in male using TDF/FTC to prevent HIV did not find an impact on fertility or pregnancy outcomes tooltip. More research is needed.

3. What are the benefits of TDF?

For people living with HIV, taking effective treatment to control the virus is very important. A treatment plan that includes TDF can be an effective and helpful option during pregnancy. Your healthcare provider can help you understand how these benefits apply to your situation.

Some possible benefits include:

Lower chance of passing HIV to your baby or partner: TDF helps lower the amount of HIV in your blood (viral load). A low or undetectable viral load greatly reduces the chance of HIV transmission during pregnancy and childbirth.
Lower chance of passing hepatitis B to your baby: TDF reduces the amount of hepatitis B virus in the blood, which helps lower the risk of transmission during pregnancy and birth. Unlike HIV treatment, TDF for hepatitis B is usually taken on its own.
Helps prevent HIV infection: When combined with another medication (emtricitabine), TDF can be used to prevent HIV in people at higher risk, including during pregnancy.
Helps protect your health during pregnancy: Keeping HIV or HBV well controlled helps support your immune system and lowers the chance of complications.

Because of these benefits, TDF is often recommended as a first-choice medication during pregnancy when treatment or prevention of HIV or hepatitis B is needed. However, every pregnancy is different. Always talk to your healthcare provider about the benefits and risks based on your situation.

4. Can TDF affect breastfeeding or milk supply (lactation)?

Breast/chestfeeding decisions can be complex and personal. If you are taking TDF, whether you can breast/chestfeed depends on why you are taking the medication and your individual situation.

TDF can pass into human milk, but the amount is very small. Studies show that babies exposed through milk usually have little to no detectable levels of the medication in their blood, and no serious side effects have been reported.

Feeding decisions can feel personal and sometimes stressful. Your healthcare team can help you:

understand your options
choose a feeding plan that is safe for you and your baby
access feeding support and resources in your community

If you have questions, talk to your healthcare professional (doctor, nurse, pharmacist, midwives) or a lactation consultant. They can support you without judgment and support you in feeding your baby.

Key Takeaways

Tenofovir disoproxil fumarate (TDF) is a medication used to treat HIV and hepatitis B, and to prevent HIV.
TDF helps lower the amount of virus in the body to be almost undetectable, which reduces greatly the chance of passing HIV or hepatitis B to the baby.
TDF is one of the most studied antiviral medications in pregnancy and is commonly recommended when needed.
Research shows TDF does no increased risks of miscarriage of birth defects compared to the usual background risk.
Studies have mixed results about the impact on growth, prematurity, and low birth weight.
TDF passes into human milk in very small amounts and is generally considered compatible with breast/chest feeding if desired. A conversation with your healthcare professional is still recommended.
Always talk to your healthcare provider before starting, stopping, or changing TDF during pregnancy or lactation.

6. Research is continuously evolving

Making informed health decisions during pregnancy also means understanding what research can tell us and what it cannot tell yet. Research on HIV medications in pregnancy and lactation has helped us learn a lot, but it is still ongoing. Here are a few reasons why more research is still needed:

More long-term studies are needed: As TDF is used more widely around the world, researchers continue to study its long-term effects during pregnancy.
Limited information on growth and bone health: Some studies are looking at how TDF may affect a baby’s growth or bone development, as well as the pregnant person’s bone health. More long-term data are needed to better understand these effects.
Ongoing monitoring is important: Even with strong safety data, researchers continue to follow people and babies over time to confirm that TDF remains safe as its use increases globally.

In the meantime, TDF remains a well-studied and commonly recommended option during pregnancy when needed. Your healthcare provider can help you understand what this research means for your health and your baby.

A big thank you to Tamara Barnett, Faranak Canani, Mia Biondi, Sarah Khan, and Caley Shukalek for their expertise on the revision of this factsheet.

Other resources

References

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