SEXUAL DIFFERENCE IN EARLY FETAL CROWN-RUMP LENGTH VERSUS GESTATIONAL-AGE IN PREGNANCIES ARISING FROM IN-VITRO FERTILIZATION

The purpose of this study was to investigate the influence of fetal se x on the crown-rump length (CRL) derived from pregnancies resulting fr om in vitro fertilization without the uncertain conception dating in t he first trimester. With ultrasonography, we performed 334 and 353 exa minations, on 88 male and 102 female fetuses, respectively, The relati onship between gestational age and fetal CRL was explored with regress ion analysis: male CRL (mm) = 1.13 x gestational age (days) - 47.39 (r = 0.97), female CRL = 1.11 x gestational age - 46.44 (r = 0.97). Thes e regression lines were mutually included in the 95% confidence interv als for each other. Our results indicate no statistically significant difference in the CRL between the two sexes, being supportive of using the identical fetal CRL criterion regardless of fetal sex for gestati onal age assessment with ultrasonography in the first trimester of pre gnancy.