Does Doxycycline in Early Pregnancy Increase Miscarriage?

Clinicians frequently prescribe doxycycline to women of reproductive age for common infections. However, recent data raise critical safety concerns regarding early gestation. A large cohort study evaluated the link between first-trimester exposure to doxycycline pregnancy loss risk. Consequently, healthcare providers must carefully evaluate antibiotic alternatives before writing prescriptions for reproductive-aged patients.

Evaluating Doxycycline Pregnancy Loss in Clinical Practice

Researchers investigated health insurance claims covering over 224,000 pregnant individuals across the United States. Specifically, they analyzed commercial MarketScan records and public Medicaid data. The team evaluated oral doxycycline exposure during the first trimester of pregnancy. In addition, they created active-comparator cohorts to reduce confounding by indication. Investigators matched patients receiving doxycycline for respiratory infections against those taking amoxicillin or macrolides. Similarly, researchers compared patients with acne against women using topical clindamycin. Therefore, this robust methodology minimized differences in baseline maternal health.

Key Findings Across Indications and Comparators

The study identified an increased risk of miscarriage among doxycycline-exposed women. For respiratory infections, doxycycline showed higher loss rates than amoxicillin in both cohorts. Specifically, the adjusted risk ratio reached 1.54 in MarketScan and 1.40 in Medicaid. Furthermore, comparisons against macrolides yielded similarly elevated risks of 1.39 and 1.36. For acne vulgaris, doxycycline significantly increased pregnancy loss in commercially insured women. However, the Medicaid acne cohort did not demonstrate a statistically significant increase. Across significant cohorts, the absolute risk differences ranged between 7 and 11 percentage points.

Clinical Implications for Prescribers

Physicians traditionally avoid tetracyclines during later pregnancy because of fetal bone and tooth staining risks. Moreover, these new findings suggest substantial danger during the first trimester as well. Clinicians should routinely question patients of childbearing potential about possible early pregnancy. Alternatively, prescribers can select safer first-line antimicrobial agents when treating routine infections. Thus, amoxicillin or macrolides remain preferable options for respiratory tract infections during pregnancy. Ultimately, thorough preconception counseling helps avoid inadvertent embryofetal exposure to tetracyclines.

Frequently Asked Questions

Q1: Why does doxycycline increase the risk of pregnancy loss?

While the exact biologic mechanism requires further research, tetracyclines cross the placenta readily. Consequently, they may disrupt early embryonic cellular growth or placental attachment.

Q2: What alternative antibiotics are safer during early pregnancy?

For common respiratory infections, doctors frequently prefer amoxicillin or select macrolides. In addition, topical therapies like clindamycin offer safer treatment for dermatologic acne flares.

Q3: Should reproductive-aged women take pregnancy tests before starting doxycycline?

Yes, clinicians should recommend pregnancy screening for women of reproductive age before starting therapy. Furthermore, healthcare providers must discuss effective contraception throughout the duration of treatment.

References

1. Winterstein AG et al. Doxycycline and Risk for Pregnancy Loss : A Multi-database, Multi-indication Cohort Study. Ann Intern Med. 2026 Nov 10. doi: 10.7326/ANNALS-26-01647. PMID: 43002780.
2. Ben Shitrit I, Idan D, Hasidim AA, et al. Doxycycline safety during pregnancy: a large population-based cohort of pregnancies. Infection. 2025;53(6):1745-1753.
3. U.S. Food and Drug Administration. Doxycycline Use by Pregnant and Lactating Women. FDA Drug Safety Communication. 2017.