The number of hydrogen bonds between adenine and thymine is not the same as that between cytosine and guanine. Adenine and thymine form two hydrogen bonds, whereas guanine and cytosine form three hydrogen bonds.
DNA with high guanine-cytosine content is more stable than DNA with low guanine-cytosine content. But hydrogen bonds are not the significant cause for the stability of the DNA. The stabilization of DNA is due to the stacking interactions mainly.
Higher guanine–cytosine (GC) content results in higher melting point. Also, the stacking interactions with adjacent bases are more favorable. So, a DNA molecule with a high content of G+C would be more stable than one with high content of A+T.