Infection

Doxycycline use in pregnancy not linked to increased risk of major malformations

October 29, 2025

Study details: This population-based cohort study analyzed 265,686 pregnancies (1998–2017) from Clalit Health Services in Israel, including live births, stillbirths, and terminations. Doxycycline exposure was classified as first trimester (≤13 weeks) or third trimester (≥27 weeks). Outcomes included major congenital malformations (diagnosed up to age 1 year) and late-pregnancy complications such as preterm birth, low birthweight, and perinatal mortality.

Results:

• First trimester: Among 2,696 exposures, major malformations occurred in 7.7% vs. 7.0% of unexposed pregnancies (adjusted relative risk, 1.07; 95% confidence interval, 0.93–1.23). No organ-specific associations or dose-response effects were observed.
• Third trimester: Exposure (n=112) was associated with increased risk of very-low birthweight, but other outcomes (preterm birth, Apgar score, perinatal mortality) were similar to unexposed pregnancies.

Clinical impact: First-trimester doxycycline appears relatively safe regarding congenital malformations, supporting its use when clinically indicated. Caution may be warranted for late-pregnancy exposure due to potential birthweight effects.

Source:

Shitrit IB, et al. (2025, August 22). Infection. Doxycycline safety during pregnancy: a large population-based cohort of pregnancies. https://pubmed.ncbi.nlm.nih.gov/40844697/