If the spell is to have a child it is possible but you won't instantly become pregnant look into all options, the spell should increase your chances.
No spell will determine the child's gender. There are old divination methods to figure out a child's gender but no spell will make you have a boy or girl. No matter how much you want one gender but get the other, it's still your child who will love you just the same. Cross the gender bridge when you come to it, just keep in mind it's your child who will love you from day one, not because of your gender, but because you're their parent.