2 abortions within 1 year. Or later?

Hi doc, I hv pcod since puberty..no periods without meds...now started hirsutism after 2 miscarriages...married life 3rd yr running.. Pre diabetic, thyroid in 2nd  pregnancy, overweight(72kg for 4'11") Husband's cholesterol level high though he is slightly overweight nd on diet always since thn, sperm count acceptable after 3 months course in both pregnancies, borderline sugar as his both parents are diabetic,insulin resistant. Lost my 1st one at 17 weeks due to SCH... Baby was all good till last second then delivered him dead..bleeding nd clots passed since week 6 till 17th on and off.. Conceived through ovulation induction after 6 months but growth stopped at 6weeks might go for d&c following following week. I will start diet and exercise after this to atleast lose 10% weight Plz do advice with your immense knowledge in this subject 1) What is the root cause for this miscarriages? 2) what precautions I should take for next? 3) what all tests should I run now? Or later?