Doxycycline Antibiotic Linked to Higher Miscarriage Risk in Early Pregnancy, Study Warns

A widely prescribed antibiotic used to treat conditions such as acne and respiratory infections has been linked to a potentially higher risk of miscarriage during early pregnancy, according to new research.

The medication, known as doxycycline, is commonly prescribed to treat bacterial infections. However, researchers are raising concerns about its use among women who may be pregnant, particularly during the first trimester.

The findings have prompted experts to call for greater awareness when prescribing antibiotics to women of reproductive age, especially when pregnancy has not yet been confirmed.

Although the research does not prove that doxycycline directly causes miscarriage, scientists say the findings highlight the importance of carefully considering medication choices during pregnancy.

What Is Doxycycline and Why Is It Prescribed?

Doxycycline belongs to a group of antibiotics called tetracyclines. It works by preventing bacteria from growing and multiplying, helping the body fight certain bacterial infections.

Doctors commonly prescribe the medication for several health conditions, including:

• Acne, particularly moderate to severe cases.
• Respiratory tract infections.
• Certain urinary and genital infections.
• Some skin infections.
• Specific infections spread by ticks and other insects.

It is an effective treatment for a range of bacterial illnesses. However, its use during pregnancy is generally avoided because of potential concerns about the developing baby.

One challenge is that many pregnancies are unplanned. This means some women may unknowingly take doxycycline before discovering they are pregnant.

Researchers from the University of Florida investigated whether exposure to this antibiotic during the first trimester could be associated with an increased risk of pregnancy loss.

Study Finds Higher Miscarriage Risk Among Women Taking Doxycycline

To investigate the possible connection, researchers examined healthcare insurance claims involving pregnant women who had been prescribed antibiotics during early pregnancy.

The study included more than 218,000 claims involving pregnant women treated for respiratory tract infections. A further 6,636 claims involved women receiving treatment for acne.

Researchers compared pregnancy outcomes among women who had taken doxycycline with those who received alternative treatments.

These included antibiotics such as amoxicillin and macrolides for respiratory infections, as well as topical clindamycin for acne.

The findings showed that women exposed to doxycycline during their first trimester had a significantly higher risk of miscarriage compared with women treated with alternative antibiotics.

Importantly, the association remained even after researchers accounted for several factors that could influence pregnancy outcomes.

These included maternal age and previous pregnancy and childbirth experiences.

The researchers also examined information from commercial healthcare claims and Medicaid databases. The association between doxycycline exposure and pregnancy loss appeared in both databases.

However, the strength of the findings differed depending on the reason the medication was prescribed.

The association was strongest among women taking doxycycline for respiratory tract infections. For women receiving the antibiotic for acne, a weaker association was identified in the commercial claims database.

Experts Warn That the Findings Do Not Prove Causation

Despite the concerning findings, medical experts have stressed that the research cannot establish that doxycycline directly causes miscarriage.

Dr Linda Gallo, from the School of Health at the University of the Sunshine Coast, who was not involved in the research, said the findings demonstrate an association rather than proof of cause and effect.

She highlighted that doxycycline remains a common treatment for severe acne, particularly when other topical treatments have failed.

Acne is also relatively common among young adult women, making the issue particularly relevant for women who could become pregnant.

Dr Gallo explained that the research provides an important reason for healthcare professionals to carefully balance the potential benefits and risks when prescribing antibiotics.

Doxycycline is generally avoided during pregnancy, particularly from the second trimester onwards, because of concerns about its potential effects on foetal bone and tooth development.

However, unexpected pregnancy can mean exposure happens before a woman realises she is expecting a baby.

Why Is Doxycycline Generally Avoided During Pregnancy?

Medication safety is particularly important during pregnancy because a developing baby can be sensitive to certain drugs.

Some medications may cross the placenta and potentially affect foetal development.

Doxycycline is generally not recommended during pregnancy because of concerns associated with the tetracycline family of antibiotics.

These concerns include possible effects on developing bones and teeth, particularly during later stages of pregnancy.

However, the latest research raises additional questions about whether exposure during the first trimester could also be associated with pregnancy loss.

Scientists have previously investigated the potential effects of doxycycline on developing embryos through animal studies. Some findings have suggested possible DNA damage, although these results cannot automatically be applied to humans.

Professor Janna Morrison from Adelaide University highlighted an important limitation of the latest research.

The study focused on pregnancy loss and did not investigate the health of babies whose pregnancies continued to full term.

Consequently, researchers cannot draw firm conclusions about whether early exposure to doxycycline has any longer-term effects on children.

She emphasised that more research is needed to understand how antibiotics may influence pregnancy and foetal development.

What Are the Symptoms of an Early Miscarriage?

A miscarriage refers to the loss of a pregnancy before 24 weeks.

Early miscarriage is relatively common, with estimates suggesting that around 10 to 20 per cent of pregnancies end in pregnancy loss.

The most recognisable symptom is vaginal bleeding, although symptoms can vary considerably.

Possible warning signs include:

• Vaginal spotting: Small amounts of pink, red or brown blood may appear on underwear or toilet paper.
• Heavy bleeding: Bright red blood or bleeding that becomes heavier and soaks through a sanitary pad.
• Abdominal pain: Cramping or discomfort in the lower stomach.
• Tissue discharge: Pink, grey or white lumps or string-like material passing from the vagina.
• Fluid discharge: A sudden release of fluid from the vagina.

Some women may experience no obvious symptoms at all.

In these cases, a miscarriage may only be discovered during a routine pregnancy ultrasound scan. This is sometimes known as a missed miscarriage.

Anyone experiencing bleeding, abdominal pain or other concerning symptoms during pregnancy should contact their healthcare provider or maternity service for medical advice.

Heavy bleeding, severe pain, fainting or feeling seriously unwell requires urgent medical assessment.

What Should Women Do If They Have Taken Doxycycline Before Discovering They Are Pregnant?

The latest findings may understandably cause concern among women who have taken doxycycline during early pregnancy.

However, experts advise against making assumptions based on the study alone.

Taking doxycycline does not mean that a miscarriage will happen. The research identified a statistical association and cannot establish an individual's pregnancy outcome.

Women who discover they are pregnant while taking the antibiotic should contact their GP, midwife or prescribing healthcare professional.

They should explain when they took the medication, the prescribed dosage and how long they used it.

A healthcare professional can assess the circumstances and recommend whether treatment should be changed or stopped.

Women should not independently start, stop or replace prescribed antibiotics without seeking appropriate medical advice.

This is particularly important because untreated bacterial infections can also present risks to maternal health and pregnancy.

Doctors Urged to Consider Safer Antibiotic Alternatives

Professor Kelton Tremellen from Flinders University said healthcare professionals should consider avoiding doxycycline in women of childbearing age who are not using reliable contraception, particularly when suitable alternatives are available.

The research found that other commonly prescribed antibiotic groups, including penicillins and macrolides, were not associated with an increased miscarriage risk in the study.

However, this does not mean every antibiotic is automatically safe during pregnancy.

The appropriate treatment depends on the infection, the patient's medical history and the stage of pregnancy.

Doctors should therefore assess individual circumstances before recommending medication.

More Research Needed Into Antibiotic Safety During Pregnancy

The latest findings highlight an important gap in medical research surrounding medication use during pregnancy.

Many women require treatment for infections and other health conditions while pregnant or trying to conceive.

However, the effects of certain medications on early pregnancy and the developing baby are not yet fully understood.

Researchers say further studies are needed to determine whether doxycycline directly contributes to miscarriage or whether other factors may explain the association.

Until more evidence becomes available, healthcare professionals are being encouraged to carefully review antibiotic prescriptions for women who could become pregnant.

The key message is that medication choices matter during pregnancy. Women should always discuss antibiotic use with a qualified healthcare professional, particularly if they are pregnant, planning a pregnancy or think they may be expecting.

Add the following Sources and References section at the end of the blog to improve credibility, transparency and trustworthiness (important for SEO and health-related content).

Sources

1. The Sun Health, Published November 9, 2026.

2. University of Florida: Research findings on doxycycline exposure during the first trimester and pregnancy loss.

3. University of the Sunshine Coast: Expert commentary from Dr Linda Gallo on doxycycline use and pregnancy safety.

4. Adelaide University: Expert commentary from Professor Janna Morrison on medication exposure and foetal development.

5. Flinders University: Expert commentary from Professor Kelton Tremellen on antibiotic prescribing for women of reproductive age.