The first child tends to get the best and the worst of parents because they are first-time parents. So the first child gets the monthly photos on the first year, the first instincts that a parent would do as a mother and as a human being. I think it would help a lot if you really wanted that child in the first place. It also helps to read up on child raising books and even pregnancy books because mothering, for me, starts once the child is in the womb. So eating correctly is a big part of it and keeping away from medications, learning to deal with migraines (I get them) without medication ad the like. The basic advantage of a first child for earnest parents is that they are likely to prepare for the child as much as possible. They want to learn what they can about parenting, they want to choose what they did in their homes that they wish to pass on. The disadvantage is that if the parent is a teen and unprepared for the pregnancy, you will have a child raising a child. Just as you have to be prepared for marriage, it helps a lot if you are prepared for parenthood.
Sometimes a child is an unexpected surprise. But if an unwed mother has the support of her own mother and siblings, (this is often the case in the Philippines) the child can still grow up loved, healthy and whole. What is important is that the child is raised in a loving, nurturing environment, whether it's by a married couple or a single parent with the help of her family.