I M 24 Yr Old.i M Conceive After 3yr Of

I m 24 yr old.i m conceive after 3yr of marriage... i had taken siddha medicine for four months... i conformed my pregnancy 16 may..doc scan & told 35 days grwth nly...advice to take folic acid with naturogest sr 300mg... i taken for 10 days... bleeding started ,27 may heavy bleeding started..miscarrage happen....doc told formation of child is not proper...so about...so pls..tell me what is the reason for miscarriage....