Metformin increases the ovulatory rate and pregnancy rate from clomiphene citrate in patients with polycystic ovary syndrome who are resistant to clomiphene citrate alone. - Vandermolen,D.T.; Ratts,V.S.; Evans,W.S.; Stovall,D.W.; Kauma,S.W.; Nestler,J.E. (Fertil Steril, 2001)