Mr.Gold may have ibingiay Henry to Regina for a 'reason' or/and 'price' 

Article:

"Henry Mills (Jared S. Gilmore) has always detested the mayor of Storybrooke. He has always known she is the evil queen. Yet, his legal mother has always loved him dearly. Evenso, Emma will naturally seek the best ways so they could be together as mother-and-child. Will Henry have a soft side for the mayor in the midst of her grief?

It has been hinted that Mr. Gold played a role in bringing Henry to the mayor when he was just baby. It will not be surprising if it would turn out that the legal documents arranged for Henry's adoption are not too "legal" after all."