Utility of the US Preventive Services Task Force for Preeclampsia Risk Assessment and Aspirin Prophylaxis.

Importance: The US Preventive Services Task Force (USPSTF) guidelines on preeclampsia risk assessment and aspirin prophylaxis (AP) have not been evaluated for clinical utility. Objective: To evaluate which characteristics in the USPSTF guidelines identify risk status and the association of preeclampsia risk with AP recommendations. Design, Setting, and Participants: This observational cohort study enrolled from July 2020 to March 2023 with data analysis performed from October to December 2024. Enrollment occurred at 11 centers throughout the US or via direct-to-participant recruitment. Pregnant participants aged 18 years or older with a singleton pregnancy less than 22 weeks' gestation were selected via convenience sampling. Exposure: The exposures were clinical factors abstracted from medical records by research coordinators, which were stratified according to USPSTF definitions of low, moderate (parity, advanced maternal age [AMA], race, and body mass index), and high (chronic hypertension, prior preeclampsia, type 1 or 2 diabetes, kidney disease, and/or autoimmune conditions) risk. Main Outcomes and Measures: Data collected included AP recommendation, presence of USPSTF-defined moderate risk factors or high risk factors, and any preeclampsia diagnosis. Effect sizes and relative risk (RR) were calculated within risk strata. Results: Of 5684 participants (median [IQR] age, 30.9 [26.4-34.6] years; 267 [4.1%] Asian; 1191 [21.0%] Black; 990 Hispanic [17.4%]; 2764 [48.6%] White; and 472 [8.3%] with other race or ethnicity), 5046 (88.8%) were at increased risk of preeclampsia (3996 [70.3%] at moderate risk and 1050 [18.5%] at high risk). A total of 2438 participants (43.1%) received an AP recommendation. The overall preeclampsia rate was 12.1% (685 participants). The PE rates specific to USPSTF categories were 3.0% for those at low risk (19 of 638 participants), 10.5% for those at moderate risk (419 of 3996 patients), and 23.5% for those at high risk (247 of 1050 participants). Among individuals with 2 or more moderate risk factors but without any high risk factor, nulliparity was associated with significantly increased risk of preeclampsia (RR, 1.48; 95% CI, 1.35-1.62; P < .001), while AMA was associated with decreased risk (RR, 0.79; 95% CI, 0.65-0.96; P = .02); there was no association with obesity (RR, 1.11; 95% CI, 1.01-1.22; P = .048) or Black race (RR, 0.95; 95% CI, 0.80-1.14; P = .63). Of 1044 participants with any high risk factors, 856 (82.0%) were recommended AP and of 634 at low risk, 538 (85.9%) were not recommended AP. In contrast, of 1942 participants with 1 moderate risk factor, 463 (23.8%) were recommended AP, and of 2032 with 2 or more moderate risk factors, 1024 (50.4%) were recommended AP. Conclusions and Relevance: In this prospective cohort study of 5684 singleton pregnancies, 89% of the population was assessed as having increased risk (moderate or high) of preeclampsia by USPSTF criteria. These findings suggest that moderate risk factors in the absence of high risk factors show no or low value for estimating the risk of developing preeclampsia, leading to nonspecific recommendations of AP in the moderate risk category.