Talk to Gynecologist on Pregnancy Issue

Hi mam, meri sis is 3 years married, she got 2 miscarriages by DNC in 2nd or 3rd month of pregnancy because baby growth was nill, now she is pregnant again, and doctor told that gestational sac iz smaller then embryo size, embryo size is 7 weeks and gestationa sac size is 5 weeks, so is there any treatment for this?? So that her pregnancy become healthy this time,