Medians for second-trimester maternal serum markers: geographical differences and variation caused by median multiples-of-median equations

Abstract

Belgian marker medians versus gestational time are found to show a pattern that is similar to that in the literature. The log-linear equation is observed to give a good fit and can be suggested as a tool for calculating median MoM values for Belgian laboratories that use Access biochemical prenatal markers.

Comparison of two different sites of measurement for transabdominal uterine artery Doppler velocimetry at 11–13 weeks

“…Right PI, left PI and mean PI were calculated for each examination. They were reported as multiples of the median (MoM) for gestational age in order to eliminate the gestational age effect21; medians for each week of gestation were calculated using our own data. Correlation coefficients (ρ) between Site A and Site B measurements and between first‐ and mid‐trimester findings were calculated using non‐parametric analysis (Spearman's rank correlation).…”

Normative Values of Second-Trimester Maternal Serum Markers Using an Automated Assay Platform for Down Syndrome Screening

“…Each of four serum markers had a similar pattern of change during the second trimester of pregnancy among various ethnic groups. 7,9,10,13 Nevertheless, unique normal values were reported among different ethnic groups. Higher levels of serum AFP, hCG, and Inh A and a lower level of serum uE3 in our population were observed in comparison of those in the Caucasian groups.…”

Evaluation of Down's syndrome screening population data sets by simulation: analyser-specific parameters may be superior to meta-analysis-derived parameters

“…33210, 33500 and 33570 with their corresponding calibrators) were used on the Beckman Coulter Access base, Access2 and Unicell DxI analysers to measure mid-trimester AFP, HCG and uE 3 results. The origin of the Belgian data studied was described in previous papers (7,8). A dataset of 862 requests derived from women being screened for Down's syndrome associated pregnancy, composed of selected pregnancies deemed to be normal based on triple test results and genetic analysis of amniotic cells in doubtful cases, was examined in a retrospective study.…”

“…A subset of 752 second-trimester results for AFP, HCG and uE 3 , with complete demographic information such as maternal weight, gestational age and age at expected day of delivery, was used to establish Gaussian population statistics of the markers, such as the mean, standard deviation (SD) and correlation coefficients between the markers. All results were expressed as MoM values, corrected for weight as described ear-lier and transformed to a log 10 scale (7,8). Normality of the distribution of the weight corrected log 10 values of the serum markers was tested with the Kolmogorov-Smirnov test.…”