Aspirin
1. Pregnancy Evidence & Regulatory Labeling
FDA Pregnancy and Lactation Labeling Rule (PLLR 8.1) & EMA SmPC Section 4.6
Clinical Risk Summary
Low-Dose (81–150 mg/day): Recommended by USPSTF and ACOG starting at 12–16 weeks gestation for women at high risk of preeclampsia. Low-dose aspirin is safe and significantly reduces preeclampsia, preterm birth, and fetal growth restriction.\n\nHigh-Dose / Analgesic (≥325–1,000 mg/day): Contraindicated from 20 weeks gestation onward due to fetal renal impairment / oligohydramnios and premature ductus arteriosus constriction.
Human Pregnancy Experience & Clinical Studies
Dozens of prospective randomized trials (CLASP, ASPRE trial) involving tens of thousands of pregnant women prove the safety and efficacy of low-dose aspirin in pregnancy.
Animal Reproductive & Developmental Toxicity Data
High-dose salicylates in animal models caused skeletal anomalies and maternal-fetal hemorrhage.
Clinical Considerations for Prescribers
For preeclampsia prophylaxis, initiate 81–162 mg daily between 12 and 16 weeks gestation and continue until 36–37 weeks. Avoid full analgesic doses in late pregnancy.
Placental Transfer
Salicylates cross the placenta readily.
2. Lactation & Breastfeeding Safety
NIH / NLM LactMed® Database & FDA Labeling Section 8.2
Summary of Use during Lactation
Low-dose aspirin (81–100 mg/day) produces minimal levels in breast milk and is considered compatible with breastfeeding. High-dose analgesic aspirin should be avoided due to the theoretical risk of Reye syndrome in the infant.
Drug Levels in Breast Milk & Relative Infant Dose
Low doses produce negligible milk concentrations; high doses produce measurable salicylate levels.
Effects in Breastfed Infants & Monitored Signs
Theoretical risk of Reye syndrome and platelet dysfunction with high doses.
Effects on Lactation & Milk Production
No effect on milk volume.
Alternate Medications with Established Lactation Data
4. Regulatory Source Provenance & Comparison
Direct attribution to official regulatory documents without synthesized consensus
| Regulatory Organization | Jurisdiction | Document / Framework | Effective Date | Official Source Link |
|---|---|---|---|---|
|
National Institutes of Health (NIH) / NLM
LactMed® Database (Drugs and Lactation)
|
United States / Global | evidence_monograph | 2026-08-01 | Official Record |