Pregnancy issue. Some insight to this!

I have conceived through ivf.  I have hypothyroidism, hypertension and gestational choleostasis. My hypertension , thyroidism and choleostasis are under control with medication. My fetal growth was proper till 28 weeks but then ac dropped from 20 % to 10 % at 32 weeks and 5% in 34 weeks . Doppler studies showed good placental blood supply and afi and fetal movements. Today I am 35 weeks 1 day. The doppler study was done on all occassions as well as today . Growth study would be done next again on 36 weeks. Can any one say what might have caused the decline in ac of the fetus and caused iugr . 34 weeks fetal weight was 1975 gms. I am taking stamlo 5 twice, labebet 100 twice, ecosprin 75 mg, eltroxin 100 mcg apart from iron and calcium . Would be helpful if anybody can share some insight to this