Ooooh who might you be?! CONGRATULATIONS on your pregnancy! And like everyone else said, you don't have to worry about staying on SW while being pregnant, it's probably the best diet you can possibly be on both for you and for baby. The only thing I would include is some olive oil every day.
I'm 37 weeks pregnant and so far I've only gained about 11lbs and everytime I've been to the doctor or midwife they've marvelled at how healthy I am and how robust and strong baby is (she's almost 7lbs already!) The doctor described my pregnancy as text book and said he wished every pregnancy could be as straight forward as mine. I was a size 10 when I got pregnant and now I'm a 12, not bad at all! I really attribute a lot of this to my diet and taking vitamins (iron, vit C and calcium). So really you're better off on SW is the BEST thing you can do for yourself. Even if you're not following it to the letter, stick to it as much as you can anyway and you'll be shocked how fit and well you'll feel throughout your pregnancy.
Congratulations once again and I wish you the very best of luck with everything!!