I've always heard that anything +/- 2cm away is considered ok. If you are measuring significantly smaller at your next visit, you might want to check it out though (ie, get an u/s and check baby's growth, check fluid level, etc.). Fundal height can vary based on baby's position, mama's "maternal cushioning" (fat
), etc. And fundal height doesn't always correlate with baby's size. In both pregnancies, my babies have measured at least 2 weeks ahead via u/s, yet my fundal height measures right on.