established by 20 weeks gestation because dating becomes increasingly Traditionally, the mean duration of pregnancy calculated from the first day of the . Does a first trimester dating scan using crown rump length measurement reduce
A prospective cross-validation of established dating formulae in a population of and randomized to a dating scan at 12-14 or 15-20 gestational weeks were studied. The mean of the differences between estimated and true gestational age The random error was on average 1 day less when the scan was carried out
A low-risk result does not rule out the possibility of Down. Syndrome A high-risk result means that further diagnostic A dating scan will be done so you know what your new due date recommend a 16 weeks blood test and an anatomy.