Surrogate motherhood is not correct, the child should have normal parents. If gays want to have a child, then they can be treated and create a normal family in which they can give birth to a child naturally.
There is nothing wrong with surrogate motherhood, but it is the upbringing which matter. Even a lot of heterosexual couples are having surrogate babies nowadays. But the gay lifestyle can be harmful for the kids. There is a high chance of sex abuse and drug addiction.