The objective of this study is to test the efficacy of low-dose aspirin (160 mg/day), given
bedtime and started early during pregnancy (≤ 15 +6 weeks of gestation) in nulliparous
pregnant women selected as "high-risk" by the presence of a bilateral uterine artery notch
and/or bilateral uterine artery PI ≥ 1.7 during the first trimester ultrasound scan (11-13+6
weeks), to prevent the occurrence of pre-eclampsia or small for gestational age at birth.