Hello! I'm not a medical professional, just the parent of a kid with diabetes. I assume by your 'machine' you mean the glucose meter? The most common reason for such swings in glucose scores is because of residue on your fingers when you test. Make sure you wash your hands well, with particular focus on your fingers, using a non-perfumey soap. Perfume soaps have extra alcohols in them which can cause your blood sugars to falsely show as being high. Ivory soap or plain Dial soap and products like that are best, in my opinion.
Another common reason for such swings is that not all glucose meters are extremely accurate. The standards they have to meet in order to be approved by the FDA are only the standards that a meter had to meet from like 1975. A product can get to market and have varying results. My personal opinion is that OneTouch meters are the best. I don't know what meter you're using (and I hope it's not a OneTouch or my endorsement won't mean much!), but that is a possibility.
That being said, blood sugars are a funny thing, and with the extra hormones running through your system because of your pregnancy you may get unexpected results. That's possible, but not as likely of explanation as one of the first two.
Good luck with your pregnancy!
You may be checking it too close together. Usually you wait at least an hour after checking it to check again. Your sugar will vary a lot. My daughter can check hers like this and it will be a difference. Try waiting an hour after checking it and see if that helps. We were told to check at meals and at bedtime unless she feels like it is low or extremely high. Hope this helps.