[Sonographic biometry of the fetus-crown-rump-length in the first half of pregnancy].

In 268 pregnant women with known duration of pregnancy the crown-rump-length of the fetus was measured by means of a real-time-scanner. For the period between week 7 + 0 to 20 + 0 normal curves are established. In addition the mean daily incremental rate is given. A maximum increment of 1,9 mm/day was found between week 12 + 0 and 13 + 0. The optimal date for the estimation of the gestational age is the early period between week 7 + 0 an 14 + 0. In this period the 96% confidential range (+/- 2 SD is +/- 7 days. To the end of the first half of pregnancy the precision of the estimation (+/- 2 SD) becomes worse (+/- 10 days). The fetal crown-rump-length could be measured in all cases from up week 7 + 0. Here we see a definite advantage of the real-time-scan-technic-in spite of a diminished precision of measuring - vs the compound-scan-technic.U