title: Underestimation of gestational age by conventional crown-rump length dating curves.
abstract: Inaccuracies in gestational age assignment based on published crown-rump length data were noted in patients with known ovulation dates. In this study, we tested the hypothesis that crown-rump length data derived from pregnancies with known ovulation dates differ from those of menstrually timed pregnancies. Seventy-two previously infertile women with known dates of ovulation had crown-rump length measurements from 35-79 days postovulation. We transformed the data to menstrual age (gestational age) by adding 14 days to the date of ovulation and compared our crown-rump length values with those of two previous reports. At corresponding crown-rump length values, the gestational ages from our data differed from those in the previous studies. We suggest using crown-rump length dating curves based on ovulation-timed pregnancies because crown-rump length data derived from menstrually dated pregnancies underestimate true gestational age.
authors.forename: S N
authors.initials: SN
authors.lastname: MacGregor
authors.forename: R K
authors.initials: RK
authors.lastname: Tamura
authors.forename: R E
authors.initials: RE
authors.lastname: Sabbagha
authors.forename: J P
authors.initials: JP
authors.lastname: Minogue
authors.forename: M E
authors.initials: ME
authors.lastname: Gibson
authors.forename: D I
authors.initials: DI
authors.lastname: Hoffman
mesh_terms: D005314:Embryonic and Fetal Development; D005260:Female; D005333:Fetus / Q000033:anatomy & histology*; D005865:Gestational Age; D006801:Humans; D010062:Ovulation Induction; D011247:Pregnancy; D014463:Ultrasonography