In Iowa, USA the law ... about birth of a child before marriage?

In Iowa, USA does the law say that you are legally married if you have a child before marriage? Because I was like that and my stepmom and I would fight because my dad, according to here has had 3 wives but from what I think he's had four because of my mom. he's been married twice then, my mom and him had me without being married and never did get married but they still had to go through a legal divorce and now he is married to my stepmom. This is bothering me so I need to know. And If you could provide a website, easy 10 points.