Beyond preeclampsia: low dose aspirin as a preventative strategy for spontaneous preterm birth.

Spontaneous preterm birth (PTB) remains a substantial challenge in healthcare worldwide. The etiology is multifactorial and includes placental insufficiency, which overlaps with the pathophysiology of preterm pre-eclampsia (PE). Low-dose aspirin (LDA) is an established preventative strategy for preterm PE by targeting placental insufficiency. This narrative summarizes current evidence for LDA as a preventive strategy for spontaneous PTB. In patients at risk of preterm PE, daily LDA (particularly when initiated before 16 weeks of gestation and at a dose ≥100 mg) prevents total PTB. Emerging evidence suggests that daily LDA also reduces total PTB in nulliparous patients. However, findings have not been confirmed in national cohort studies, largely due to suboptimal treatment adherence. Recent studies also suggest a preventive effect of LDA in patients with a history of spontaneous PTB, although these studies are underpowered to draw firm conclusions. Overall, trends point towards a preventive effect of LDA, providing a safe and inexpensive treatment for spontaneous PTB. The effectiveness may be limited to subgroups based on the underlying mechanism of spontaneous PTB. Future research should focus on large population-based implementation studies focusing on treatment adherence, as well as identifying subgroups most likely to benefit from LDA.