From the Guidelines
Taking a single dose of doxycycline during pregnancy is likely to pose minimal risk to the developing fetus, especially if taken during the first trimester, but it is still recommended to consult a healthcare provider due to potential risks associated with tetracycline use in pregnancy 1. The primary concern with doxycycline use in pregnancy is its potential to cause tooth discoloration, enamel hypoplasia, and bone growth inhibition in the fetus, particularly when used during the second or third trimester. However, the risk associated with a single dose is considered low, and most reports in humans have found no evidence that use during pregnancy is associated with increased risk of birth defects 1. It is essential to note that doxycycline can cross the placental barrier and affect fetal development, particularly calcifying structures like teeth and bones. If a pregnant individual has taken a single dose of doxycycline, they should contact their healthcare provider to discuss their specific situation and potential alternative antibiotics that are considered safer during pregnancy, such as penicillins, cephalosporins, or erythromycin. Some studies suggest that alternative treatments like trimethoprim/sulfamethoxazole may be used during pregnancy, but the decision should be made under the guidance of a healthcare provider due to the potential risks and benefits associated with these medications 1. Ultimately, the decision to use any medication during pregnancy should be made with caution and under the guidance of a healthcare provider to minimize risks to the fetus and ensure the best possible outcome for both the mother and the child.
From the FDA Drug Label
Pregnancy: Teratogenic effects. Pregnancy Category D: There are no adequate and well-controlled studies on the use of doxycycline in pregnant women The vast majority of reported experience with doxycycline during human pregnancy is short-term, first trimester exposure. An expert review of published data on experiences with doxycycline use during pregnancy by TERIS – the Teratogen Information System – concluded that therapeutic doses during pregnancy are unlikely to pose a substantial teratogenic risk (the quantity and quality of data were assessed as limited to fair), but the data are insufficient to state that there is no risk
The use of doxycycline during pregnancy is classified as Pregnancy Category D, indicating that there is evidence of risk to the human fetus. However, an expert review suggests that therapeutic doses are unlikely to pose a substantial teratogenic risk. Since the question is about taking one dosage of doxycycline, the risk is likely to be low, but the data are insufficient to state that there is no risk. Therefore, it is recommended to exercise caution and consult a physician if doxycycline is taken during pregnancy, even if it's just one dose 2.
From the Research
Effects of Doxycycline on Pregnancy
- Doxycycline is classified as a class D drug, which means it is contraindicated in pregnancy and in children under 8 years of age 3.
- However, some studies suggest that doxycycline may be safe to use during pregnancy, especially when the benefits outweigh the risks 3, 4.
- A systematic review of the available literature on doxycycline use in pregnant women and children found no correlation between the use of doxycycline and teratogenic effects during pregnancy or dental staining in children 3.
Adverse Pregnancy Outcomes
- One study found that doxycycline was associated with cardiovascular malformations (OR 2.4,95% CI 1.2-4.7) and spontaneous abortion (OR 2.8,95% CI 1.9-4.1) 5.
- Another study found that doxycycline use during pregnancy was associated with premature delivery, spontaneous abortion, intrauterine death, and congenital anomalies, but the number of reported events was small and may have been influenced by concomitant medications 4.
Placental Transfer of Doxycycline
- Doxycycline, like other antibiotics, crosses the placenta and reaches the fetus 6.
- The type of placental transfer involved is not specified for doxycycline, but it is likely to be incomplete, meaning that concentrations are lower in the cord than maternal plasma 6.
Precautions and Recommendations
- Until more definitive data are developed, doxycycline should be prescribed with caution for pregnant women and young children, and courses of treatment should be of as short a duration as possible 7.
- The decision to use doxycycline during pregnancy should be made on a case-by-case basis, taking into account the potential benefits and risks 3, 5, 4.