Hi , How are you doing ?
Let me give a positive note to begin with. If she has got pregnant once , no matter what the result was, she has very good chance of getting pregnant.
Kindly see if the following checklist of investigations is done
Husband- 
Semen analysis at least 2-  done 4 weeks apart preferably in an 
infertility center ( examination done by andrologist), Blood sugars
Wife - Blood Sugars, 
Thyroid profile          
Ultrasound scans to evaluate 
Uterus , Ovaries & adnexa
          Confirm tubal patency- most important- Tube is the connection 
          between uterus & ovaries( the bridge where sperm meets the egg & 
          forms a baby) this is size of hair follicle & cannot be seen on scans.
           So check with HSG( Xray with dye), or SSG ( Scan with dye) or 
           Laparoscopy
If all this done & found normal , nothing can stop a 
pregnancy with God's will
Hope I have cleared your query, do write back if any more quries
All the best
Dr.Balakrishnan