okay so this has never happened to me before. I went to my 23 week appt and I was measuring 25cm and…

okay so this has never happened to me before. I went to my 23 week appt and I was measuring 25cm and then I went to my 24 week appt and I was measuring 23cm. Has this happened to anyone before? I have always measured agead not behind lol. I did have my glucose test at my 24 week appt and didn't eat anything could that be it?