Get more rest and time away from your three existing children. Hire a mommy's helper now so that the routine is established by the time your fourth arrives. Delegate what you can to anyone willing to help. REMEMBER - the family is only happy when mommy is happy. Take care of YOURSELF and then the rest will fall into space. Since you are older, rest and exercise cautiously. If you don't get enough rest (ie at least 8 hours of sleep, time off of your feet in the after noon, and a walk three times a week), your body will not be able to keep up. Believe me, my second child came at 38 and my doctor kept telling me to rest and I didn't believe him. Well, I should have because now I have read research spelling out how important it is to rest and sleep for your brain and body to function properly. Don't cheat yourself. YOu put out so much energy as a mom and somehow our society downplays how hard we work. Rest, rest, rest.