TRANSVAGINAL CROWN-RUMP LENGTH MEASUREMENTS OF 224 SUCCESSFUL PREGNANCIES WHICH RESULTED FROM GAMETE INTRAFALLOPIAN TRANSFER OR IN-VITRO FERTILIZATION

The crown-rump lengths (CRL) of 224 pregnacies which resulted from gam ete intra-Fallopian transfer (GIFT) or in-vitro fertilization (IVF) we re assessed two to four times in the first trimester. The results were compared with some of the published articles which assessed CRL in sp ontaneous and induced pregnancies. The range of CRL measurements from this study was generally smaller than the previously published data, a lthough all women went on to deliver normal fetuses at full term weigh ing > 2.5 kg. It was not possible to identify a clear reason for this finding, but factors which might have been relevant included populatio n differences, more accurate estimation of ovulation/conception time, the exclusive use of vaginal ultrasonography in this study and variati ons in the embryonic implantation/development times. There is a need t o review the commonly used CRL charts in view of the increasing use of transvaginal ultrasonography and the increasing number of pregnancies with known ovulation/conception times. Each centre should aim to esta blish the normal CRL range for its own population.