Medians and correction factors for biochemical and ultrasound markers in Chinese women undergoing first-trimester screening for trisomy 21 (original) (raw)
2009, Ultrasound in Obstetrics and Gynecology
Objective To establish normative values and distribution parameters of first-trimester maternal serum free β-human chorionic gonadotropin (β-hCG), pregnancyassociated plasma protein-A (PAPP-A) and fetal nuchal translucency (NT) thickness in Chinese women and to examine the effects of covariates on their levels. Methods Maternal serum free β-hCG, PAPP-A and fetal NT were measured in 9762 women presenting for first-trimester combined screening for Down syndrome at 11 to 14 weeks of gestation. Individuals' markers were converted to multiples of the median (MoM) using expected medians estimated by performing a weighted regression analysis. Multivariate regression analysis was performed to assess the influence of maternal weight, parity, ethnicity, chorionicity in twin pregnancies, smoking, insulin-dependent diabetes and mode of conception on individual marker MoM levels. Results Both free β-hCG and PAPP-A median values demonstrated an exponential relationship with gestational age in days. Multivariate regression analysis indicated that free β-hCG MoM was statistically significantly dependent on maternal weight (P < 0.0001) and chorionicity in twin pregnancy (both monochorionic and dichorionic P < 0.0001), that PAPP-A MoM was dependent on maternal weight (P < 0.0001), parity (P < 0.0001), chorionicity in twin pregnancy (both monochorionic and dichorionic P < 0.0001) and mode of conception (P = 0.002), and that fetal NT-MoM was dependent on maternal weight (P = 0.0006) and mode of conception (P = 0.012). Conclusion Normative values have been generated to allow conversion of NT, free β-hCG and PAPP-A to their MoM equivalents and correction factors have been determined to adjust for maternal and pregnancy characteristics for use in ethnic Chinese women undergoing first-trimester screening for aneuploidy.
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PLOS ONE
Objective To establish normative weight-adjusted models for the median levels of first trimester serum biomarkers for trisomy 21 screening in southern Thai women, and to compare these reference levels with Caucasian-specific and northern Thai models. Methods A cross-sectional study was conducted in 1,150 normal singleton pregnancy women to determine serum pregnancy-associated plasma protein-A (PAPP-A) and free β-human chorionic gonadotropin (β-hCG) concentrations in women from southern Thailand. The predicted median values were compared with published equations for Caucasians and northern Thai women. Results The best-fitting regression equations for the expected median serum levels of PAPP-A (mIU/L) and free β-hCG (ng/mL) according to maternal weight (Wt in kg) and gestational age (GA in days) were: median PAPP À A ¼ e ½8:4454 À 0:01950 ðWtÀ 55Þþ 0:05747 ðGAÀ 87Þ ; and median free b À hCG ¼ e ½3:6409 À 0:01703 ðWtÀ 55ÞÀ 0:03345 ðGAÀ 87Þ : Both equations were selected with a statistically significant contribution (p< 0.05). Compared with the Caucasian model, the median values of PAPP-A were higher and the median values of free β-hCG were lower in the southern Thai women. And compared with the northern Thai models, the median values of both biomarkers were lower in southern Thai women.
Prenatal Diagnosis, 2007
Objective To establish normative values and distribution parameters of first-trimester screening markers, namely, fetal nuchal translucency (NT), maternal serum free β-human chorionic gonadotrophin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A), at 10 to 13 +6 weeks of gestation in Saudi women and to evaluate the effect of co-variables including maternal body weight, gravidity, parity, fetal gender, twin pregnancy, smoking and ethnicity on these markers.
Archives of Gynecology and Obstetrics, 2012
Non-invasive Wrst trimester screening for fetal aneuploidy is based on the consideration of fetal nuchal translucency, biochemical serum markers 'pregnancy associated plasma protein A' (PAPP-A), and 'free beta-humane chorionic gonadotropin' (f -hCG). The blood sera of 168 pregnant women in 11 + 0 to 13 + 6 weeks of gestation were examined by both the COBAS (Roche Holding GmbH, Germany) and KRYPTOR (Brahms GmbH, Germany) immunoassay systems in two quality controlled laboratories. The concentration values were converted into multiple of median (MoM) values and compared through a two-tailed t test. The concentration values of PAPP-A diVered signiWcantly from each other (p < 0.0001). COBAS produced on average 0.09 MoM higher values in comparison to KRYPTOR (CI 95% = 0.06-0.11 MoM). In contrast, the concentration values of f -hCG did not diVer signiWcantly (p value = 0.20). The values produced by COBAS were on average only 0.02 MoM higher in comparison to KRYPTOR (CI 95% = ¡0.01 to 0.05 MoM). Which of the two systems generates the more precise results should be evaluated in a large-scale prospective study with the pregnancy outcomes.
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