Previous studies have reported that aspirin can be used to reduce the prevalence of both early-onset preeclampsia (ePET) and fetal growth restriction (FGR). The prevention of FGR would improve both pregnancy and infant outcomes and could also reduce costs to the health care system. FGR leads to insufficient oxygen and nutrient delivery to the fetus, exposing it to antenatal risks. Further, these babies are at an increased risk of developing adult cardiovascular disease, diabetes, and metabolic syndrome later in life. The goal of this study was to determine if aspirin prescribed to decrease the risk of ePET reduces the prevalence of small for gestational age (SGA) neonates. Women were referred for first trimester screening for the study. In the observational cohort, the main intention of screening was to evaluate for the risk of aneuploidy. In the intervention cohort, the main intention of screening was to define risk for aneuploidy as well as ePET. The study included 3 consecutive cohorts of women screened for ePET. The screening process involved a Fetal Medicine Foundation screening algorithm between 11 and 13+6 weeks of pregnancy. The first observational cohort evaluated data between April 16, 2010, and March 9, 2012. This first cohort was used to verify the ePET algorithm in an Australian population. The second cohort was evaluated between April 2, 2014, and October 31, 2014. This cohort was screened prospectively, and high-risk women were prescribed 150 mg of aspirin to take before bed each night until 34 weeks as a prophylaxis against preeclampsia. The third cohort followed the same medication process and was evaluated between September 3, 2015, and December 28, 2017. The second and third cohort were merged to form the intervention cohort. The women in the intervention cohort were identified as being "high risk" if they had an ePET risk >= 1 in 100 and were instructed to take 150 mg aspirin to take every night until 34 weeks. Individual medical records were reviewed and data for pregnancy outcomes included gestation at the time of delivery, infant sex, and birthweight. Statistical analysis was performed in STATA. There were 3066 women identified for the observational cohort. Of these, 53 were excluded for delivery before 24 weeks, termination of pregnancy, fetal death in utero, or missing data. Therefore, there were 3013 women and infants included in this cohort. Of these women, 2662 screened low risk for ePETand 351 screened high risk. In all, 8572 women were identified for the intervention cohort; 144 women were excluded due to birth before 24 weeks, termination of pregnancy, and fetal death in utero. Therefore, 8428 women were included in this cohort. Of these women, 7437 screened low risk for ePET and 991 screened high risk. Women in the observational and interventional groups had slightly different baseline characteristics: women in the interventional cohort were more likely to be nulliparous (57.6% vs 52.5%); the observational cohort contained more White women (67.6% vs 64.8%). There were also more women entering pregnancy with a healthy body mass index (defined as between 18 and 24.9) in the observational cohort (62.8% vs 60.7%) and fewer women classified as obese (with a bodymass index greater than or equal to 30 kg/m2) (10.96% vs 11.7%). There were fewer smokers in the intervention cohort (2.2% vs 3.0%). The mean arterial blood pressure (81.2 vs 88.97 mm Hg), uterine artery PI (1.64 vs 1.73 multiples of the median), and PAPP-A (1.21 vs 1.27 multiples of the median) contained lower values in the intervention cohort. Gestational age at the time of delivery in the observational cohort was greater (277 vs 275 days). Finally, birthweight was slightly higher in the observational cohort (3391 g) compared with the interventional cohort (3345 g). The observational cohort consisted of 3013 women, and the interventional cohort consisted of 8424 women. Women who screened high risk for ePET were 3 to 4 times more likely to give birth to an SGA neonate in both the observational and interventional cohorts (6.8% vs 1.9% and 6.0% vs 1.8%, respectively). Of the women who screened high risk, there were no statistically significant differences in the number of SGA neonates for women who received aspirin compared with women who did not (6.6% vs 6.0%; adjusted odds ratio, 0.84 [0.50-1.42]). This study found that women who screen high risk for ePET have a greater chance of delivering an SGA infant. However, there was no reduction in the number of SGA neonates when aspirin was prescribed to these women.
