Fetal age: Methods of estimation and effects of pathology

Abstract

Accurate identification of fetal age is important in a wide variety of circumstances. Seventeen anthropometric and radiographic measurements were taken on fetuses between 15 and 42 weeks of gestational age, both with and without pathologic conditions. A full evaluation including radiographic, karyotypic, gross anatomic, and histologic examination of the fetus and placenta identified 72 individuals as nondysmorphic with no signs of chronic uterovascular insufficiency. These specimens served as the control group. Based on least-squares regressions of this group, age-estimation equations were calculated for all variables. Six models were adequately described by linear equations; the remaining 11 required a quadratic term. Based on standard error of the estimate (S(y:x)), skeletal measures proved the most accurate age estimators. Pathologic conditions were shown to have an influence on age estimation indicated by high levels of inaccuracy and, in some instances, significant bias.

Radiographic fetal osteometry: Approach on age estimation for the portuguese population

“…The GA had to be converted to weeks, in order to compare the results obtained with the other three equations. Only the femur was compared since this bone is more closely related to fetal length and GA [3,9,13,18,19]. In order to avoid methodological bias, fifteen fetuses of known gestation age not included in the original regression analysis were used to evaluate which formula is the most reliable to estimate GA in Portuguese fetal remains.…”

“…The decision of employing XR measurements was due to the fact that they are more reliable than ultrasound measurements and can easily be used when the subject of study (in forensic context, for instance) retains soft tissues [4,17,18]. This was a retrospective cohort study.…”

“…Yet, the lack of large identified skeletal collections including fetuses precludes the existence of appropriate formulae [8]. Consequently, these tables are mostly based on ultrasonographic measurements [9][10][11][12] that might differ from actual measurements on dry bone [17,18]. Moreover, formulae applicable on dry bones have twosteps and are mostly supported by outdated literature [8,13].…”

A Genomewide Linkage Scan for Quantitative Trait Loci Influencing the Craniofacial Complex in Baboons (Papio hamadryas spp.)

“…This correction factor is based on the formula X ðTH À DÞ= TH, where X is the radiographic measurement, TH is the tube height (a constant 37 in. ), and D is the distance from the object (in this case the cranial midline defined as one-half of head width) to the film (Sherwood et al 2000).…”

Anthropometric Data Analytics: A Portuguese Case Study

“…Regarding anthropometric data analytics, other published papers often approach the validity of different measured variables for conceptual age estimation 6 -10 , and the quantitative standards of those measurements for foetal and neo-natal autopsy 11 . Regression analysis and model fitting are widely accepted and used in this field of work, hence being viewed as reliable tools for knowledge production 12 . Other relevant publications may also be found, discussing the relationship between different methods of analysis and discriminating regression properties, enabling model validation for subsequent selection 13,14 .…”