What Causes Miscarriages While Having PCOD?

Hi Doctor.Hope u r good. I was diagnosed with PCOD on 1 month back. I got married 2 years ago. Agter married my cycle are eragular. My weight is 70 kg bp is normal age -27. I dont have thyroid problems. Doctor says i m overweight. Then u use PCOD 3month. And u reduce weight... i had already 2 miscarage. I dont undrstand i m healthy so why miscarage..pls help