A reassessment of biochemical marker distributions in trisomy 21‐affected and unaffected twin pregnancies in the first trimester

To estimate the difference between levels of the two biochemical markers pregnancy‐associated plasma protein‐A (PAPP‐A) and maternal serum free β‐human chorionic gonadotropin (free β‐hCG) in twin pregnancies relative to singleton pregnancies and establish an improved screening procedure for chromosomal abnormalities such as trisomy 21 in twin pregnancies.

[1]  C. Comas,et al.  Early first‐trimester free‐β‐hCG and PAPP‐A serum distributions in monochorionic and dichorionic twins , 2012, Prenatal diagnosis.

[2]  D. Wright,et al.  First‐trimester combined screening for trisomy 21 at 7–14 weeks' gestation , 2010, Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology.

[3]  L. Chitty,et al.  Fetal Size and Dating: Charts Recommended for Clinical Obstetric Practice , 2009 .

[4]  N. Tørring.  Performance of first-trimester screening between gestational weeks 7 and 13. , 2009, Clinical chemistry.

[5]  M. Blankenstein,et al.  Early first‐trimester free β‐hCG and PAPP‐A serum distributions in monochorionic and dichorionic twins , 2009, Prenatal diagnosis.

[6]  N. Uldbjerg,et al.  Improved performance of first‐trimester combined screening for trisomy 21 with the double test taken before a gestational age of 10 weeks , 2008, Prenatal diagnosis.

[7]  K. Kagan,et al.  Screening for trisomies 21, 18 and 13 by maternal age, fetal nuchal translucency, fetal heart rate, free beta-hCG and pregnancy-associated plasma protein-A. , 2008, Human reproduction.

[8]  K. Kagan,et al.  Screening for trisomy 21 by maternal age, fetal nuchal translucency thickness, free beta‐human chorionic gonadotropin and pregnancy‐associated plasma protein‐A , 2008, Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology.

[9]  K. Kagan,et al.  A mixture model of nuchal translucency thickness in screening for chromosomal defects , 2008, Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology.

[10]  K. Kagan,et al.  Screening for trisomy 21 in twin pregnancies in the first trimester: an update of the impact of chorionicity on maternal serum markers , 2008, Prenatal diagnosis.

[11]  N. Wald,et al.  Prenatal screening for Down syndrome and neural tube defects in twin pregnancies , 2005, Prenatal diagnosis.

[12]  K. Nicolaides,et al.  Screening for trisomy 21 in monochorionic twins by measurement of fetal nuchal translucency thickness , 2005, Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology.

[13]  K. Spencer,et al.  Age‐standardisation when target setting and auditing performance of Down syndrome screening programmes , 2004, Prenatal diagnosis.

[14]  K. Nicolaides,et al.  Screening for trisomy 21 in twins using first trimester ultrasound and maternal serum biochemistry in a one‐stop clinic: a review of three years experience , 2003, BJOG : an international journal of obstetrics and gynaecology.

[15]  K. Nicolaides,et al.  A first trimester trisomy 13/trisomy 18 risk algorithm combining fetal nuchal translucency thickness, maternal serum free β‐hCG and PAPP‐A , 2002, Prenatal diagnosis.

[16]  K. Nicolaides,et al.  First trimester prenatal diagnosis of trisomy 21 in discordant twins using fetal nuchal translucency thickness and maternal serum free β‐hCG and PAPP‐A , 2000, Prenatal diagnosis.

[17]  K. Spencer.  Screening for trisomy 21 in twin pregnancies in the first trimester using free β‐hCG and PAPP‐A, combined with fetal nuchal translucency thickness , 2000, Prenatal diagnosis.

[18]  Mark Woodward,et al.  Epidemiology: Study Design and Data Analysis , 1999 .

[19]  H. Cuckle.  Down's syndrome screening in twins , 1998, Journal of medical screening.

[20]  K. Nicolaides,et al.  Screening for trisomy 21 in twin pregnancies by maternal age and fetal nuchal translucency thickness at 10–14 weeks of gestation , 1996, British journal of obstetrics and gynaecology.

[21]  K. Nicolaides,et al.  The lambda sign at 10–14 weeks of gestation as a predictor of chorionicity in twin pregnancies , 1996, Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology.

[22]  I. Timor-Tritsch,et al.  Early and simple determination of chorionic and amniotic type in multifetal gestations in the first fourteen weeks by high-frequency transvaginal ultrasonography. , 1994, American journal of obstetrics and gynecology.

[23]  J. Fleming,et al.  A CRITICAL EVALUATION OF SONAR “CROWN‐RUMP LENGTH” MEASUREMENTS , 1975, British journal of obstetrics and gynaecology.