See Will Arnett's 'surprised' reaction to Megan Fox's #NotTheFather postA collective gasp was heard round the celebrity entertainment world earlier this week when Megan Fox revealed that she's pregnant with her third child -- and her estranged husband Brian Austin Green turned out to be the father. Given that they filed for divorce last August, the question on everybody's mind was, Gee, how'd that happen? (Apart from the obvious, that is.)Megan Fox is pregnant with her third child."You know, nothing is planned," Green told People at the Toyota Grand Prix of Long Beach Celebrity Race on Friday. "None of them are ever planned. You kind of just go with it." Green, who turns 43 this year, added, "At my age, to be having three babies, is crazy." He does know how fertility works, right?Fox hasn't commented on the pregnancy or the relationship but the pair has spent time together - clearly, right? - since filing for divorce. Paperwork is still pending though, and, according to E!, it may be put on hold a while.