What I do is drag both the male and female to the bedroom. Then I drag the male onto the female. I keep on dragging him onto her until it says 'Trying For A Baby'. Once it says that, I continually praise the female until 5 seconds after she gets on the bed. After that, I make sure that I can't see the couple on my screen anymore. Last time I did this, I got twins! I just used a woman who 'Not Really' wants kids and a male who 'Definitely' wants kids. Hope this helped!!
P.S. Make sure that the male and female are in an elated mood if you want twins.