(532) Effect of Low-Dose Aspirin on Preterm Prelabor Rupture of Membranes in Low-Risk Nulliparous Women

Objective: We previously showed that low-dose aspirin (LDASA) is associated with a reduction in spontaneous preterm birth < 34 weeks (SPTB34) (Andrikopoulou, Gyamfi-Bannerman, et al. AJOG 2018), likely by an anti-inflammatory mechanism. Inflammation likely plays a role in preterm prelabor rupture of membranes (PPROM). Our objective was to determine whether a reduction in PPROM drove the decrease in SPTB.

Study Design: This was a secondary analysis of a randomized controlled trial of LDASA for the prevention of preeclampsia in low-risk, nulliparous women. Low risk was defined by the absence of medical complications, including hypertension, renal disease, and diabetes. We included non-anomalous singleton gestations that delivered preterm, and rates of PPROM vs. preterm labor (PTL) with intact membranes were compared by LDASA exposure. Logistic regression was performed to control for clinically relevant confounders. We then performed sensitivity analyses to evaluate the rates of SPTB34 in PPROM vs. PTL with intact membranes by LDASA exposure.

Results:

197 subjects were included (Figure 1). Of those, 95 (48.2%) received LDASA and 102 (51.8%) received placebo. There were no significant differences in baseline characteristics between the two groups. The rate of PPROM was similar in the LDASA and placebo groups (40.0% vs. 43.1%, respectively; p=0.66). This finding held true when adjusting for confounders (aOR 0.87; p=0.65). Limiting the analysis to those with PPROM, the median gestational age at delivery was similar in both groups, 35 weeks (IQR 34, 36) in the LDASA group and 34 weeks (IQR 32, 36) in the placebo group (p=0.62). The rate of SPTB34 was significantly lower in the LDASA group (18.4% vs. 43.2%; p=0.02). When assessing only those with PTL/intact membranes, the difference in SPTB34 was not significant (19.3% vs. 29.3%, p=0.21).


Conclusion: Administration of LDASA does not reduce the rate of PPROM overall, but SPTB34 by PPROM was less frequent in the LDASA group compared to placebo. A larger sample is needed to confirm these findings.