My uterine ultrasound showed fetus arterial blood flow is restricted and I am adviced to have Aspirin. Why?

Hello doctor,

I am a 30-year-old. I had IVF frozen embryo transfer due to my husband having a reciprocal balanced translocation. The embryo was tested genetically to ensure it was not unbalanced before transfer. I had a 13 weeks and one-day ultrasound that showed uterine arterial PI in the right artery of 2.27 and left artery of 2.75. CRL is 7.65cm.Right, Ut-RI is 0.83, and Lt Ut-RI is 0.87.

Blood flow to heart and kidney of the fetus was all good, I think. HR was 156. Growing two or three days ahead of the due date. All the other measurements looked good. My doctor told me to take Aspirin 150 mg daily, which will start today. I am seeing my doctor next week but have some questions. General pregnancy symptoms such as the blocked nose and an associated sinus headache. I take a pregnancy vitamin and an extra small dose of iron and vitamin D. I also take Levothyroxine 50 mcg daily. My mother had four kids without any preeclampsia. My aunt had preeclampsia with delivery at seven months.

My questions are as follows.

1. Can this improve? Is this something that maybe my uterine arteries are a bit slow to develop and will catch up in the next week or so?

2. What is the accuracy of this ultrasound?

3. Fetal development is otherwise healthy, what is the chance this restriction of blood flow will cause fetal growth restriction, preeclampsia with FGR or any other effects too baby?

4. Does restricted uterine arterial blood flow mean that there will be fetal growth restriction? My BP measured on the same day was 110/77. I did a urine analysis but did not know about the results. Does restriction in blood flow through uterine arteries mean there will be a restriction in blood flow through the placenta and umbilical cord and growth restriction in the baby? Or can there be a restriction in uterine blood flow without effect in the baby?