Study Links Doxycycline Use in Early Pregnancy to Higher Miscarriage Risk
10 Nov 2026
Australian health experts say the findings highlight the importance of carefully choosing antibiotics for women who are pregnant or may become pregnant.
Researchers published the findings in Annals of Internal Medicine. The study found that doxycycline use for respiratory infections was linked to a 40–54% higher risk of pregnancy loss compared with amoxicillin. Compared with macrolide antibiotics, the risk was 36–39% higher.
Doxycycline is commonly prescribed for selected bacterial infections and acne. It is also among the four most frequently dispensed antibiotics in Australia.
Dr Linda Gallo from the University of the Sunshine Coast said the findings were an important reminder for healthcare professionals to consider antibiotic choices when treating women of reproductive age. She noted that unplanned pregnancies mean some women may take the medication before knowing they are pregnant.
The US research team examined health insurance records covering more than 220,000 pregnancies across commercial and Medicaid databases. They compared women who received doxycycline during the first trimester with those prescribed alternative antibiotics.
For respiratory infections, both databases showed a higher risk of pregnancy loss among women who received doxycycline. For acne treatment, the increased risk appeared in the commercial insurance data but was not found in the Medicaid database.
Dr Gallo said the findings were consistent across both databases for respiratory infections. However, she stressed that the study does not prove doxycycline directly causes miscarriage.
Professor Kelton Tremellen, a gynaecologist and reproductive medicine expert at Flinders University, said the results add to concerns about the medication's possible effects on early placental development.
He advised doctors to consider other suitable treatments for women of reproductive age who are not using reliable contraception.
Professor Janna Morrison from Adelaide University said the study's approach was useful because researchers compared patients being treated for similar conditions with different antibiotics.
She explained that comparing patients with the same health conditions can help doctors make better-informed decisions about treatment options.
However, Professor Morrison noted that the research only examined pregnancy loss. It did not assess outcomes in pregnancies that continued to full term or the longer-term health of babies.
She said further research is needed to understand the possible effects of antibiotics on early pregnancy and child development.
The study authors said their findings provide additional information to help guide decisions about treating and preventing infections during pregnancy.
Study Links Doxycycline Use in Early Pregnancy to Higher Miscarriage Risk
Source: Annals of Internal Medicine; RACGP newsGP.