First of all let me tell you I feel your pain. My Wife and I have been married over six years, she is four months pregnant with our first child, and we have not had sex since some time in April due to the worst case of morning sickness ever. I also apologize if this advice has been given to you already, I lack the patience to read all the replies.

The thing I found that worked the most(when we were still able to have sex, I'm not complaining pregnancy is a wonderful thing just a minor...delay) when she began to show interest in me early in the evening(she has this thing about only having sex at night) I would play on it. I would go over and sit with her on the couch hold her close, possibly rub her back or her shoulders. The trick is to keep the flame burning. I have found just by being sweet and loving to her that sex occurs much more often. Understand though most people with children and hectic work schedules have sex only once a week if they are lucky. Remember the love and respect you have for your Wife, and you will continue to have a respectable and regular sex life. Enough preaching though I wish you luck and happiness.