What Are The Side Effects Of Using Metformin During Pregnancy?

i have 3 weeks pergnancy symtomps are breast tendrness and lower abd cramping same menses like no other symptom pregnancy test positve on stip my LMP was 10 april.i am on metformine 500mg bd bcoz i hve dignosed 6 months back polysystic ovarian syndrom.is metformine safe in pregnancy and abd crmping is normal or not plz help me thanks.