My magic number is three . . . I hope. Blessed with two beautiful, healthy children, I almost feel guilty wanting to add one more to our lil gang, but I always thought I wanted four. Having said that, after experiencing a total of 18 months of pregnancy, my body isn't too pumped for another 40 week adventure, much less 80. Sometime during my son's first few months of life, I decided I could do it one last time. Some women always knew how many children they wanted, while most waver on the subject for years. Mums like Michelle Duggar may never know their limit until biology gives them the natural answer. Others take matters into their own hands and attempt to predict their familial outcome with a lil help from good ol' science. When did you know your magic number?