Medians and correction factors for biochemical and ultrasound markers in Chinese women undergoing first-trimester screening for trisomy 21.

Abstract

OBJECTIVE:

To establish normative values and distribution parameters of first-trimester maternal serum free beta-human chorionic gonadotropin (beta-hCG), pregnancy-associated 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 beta-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 beta-hCG and PAPP-A median values demonstrated an exponential relationship with gestational age in days. Multivariate regression analysis indicated that free beta-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 beta-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.

• Authors: D S Sahota, T Y Leung, T Y Fung, L W Chan, L W Law, T K Lau
• Journal: Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology (Ultrasound Obstet Gynecol) Vol. 33 Issue 4 Pg. 387-93 (Apr 2009) ISSN: 1469-0705 [Electronic] England
• PMID: 19306471 (Publication Type: Journal Article)
• Copyright: (c) 2009 ISUOG. Published by John Wiley & Sons, Ltd.

Chemical References

• Biomarkers
• Chorionic Gonadotropin, beta Subunit, Human
• Pregnancy-Associated Plasma Protein-A

Topics

• Adolescent
• Adult
• Biomarkers (blood)
• Chorionic Gonadotropin, beta Subunit, Human (blood)
• Crown-Rump Length
• Down Syndrome (diagnosis, diagnostic imaging, ethnology)
• Epidemiologic Methods
• Female
• Fetal Diseases (diagnosis, diagnostic imaging, ethnology)
• Gestational Age
• Hong Kong (epidemiology)
• Humans
• Male
• Maternal Age
• Middle Aged
• Nuchal Translucency Measurement
• Pregnancy
• Pregnancy Trimester, First
• Pregnancy-Associated Plasma Protein-A (metabolism)
• Prenatal Diagnosis (methods)
• Reference Values
• Young Adult