Prenatal screening in the first trimester of pregnancy

Appropriate biochemical parameters in first-trimester screening for Down syndrome

“…There have been nine published first-trimester parameter sets based on at least PAPP-A and free -hCG (Spencer et al, 1994;Macintosh et al, 1994;Brambati et al, 1994;Wald et al, 1996;Krantz et al, 1996;Berry et al, 1997;Forest et al, 1997;Haddow et al, 1998;Wheeler and Sinosich, 1998). Even the largest set Krantz et al (1996) 0.1300 (483) 0.0527 (22) Forest et al (1997) 0.1300 (500) 0.0425 (18) Berry et al (1997) 0.0557 (227) 0.1757 (52) Haddow et al (1998) 0.0630 (3169) 0.0110 (48) Wheeler and Sinosich (1998) 0.0586 (673) 0.0550 (17) Tsukerman et al (1999) 0.0576 (1291) 0.0480 (29) Krantz et al (1996) 0.0849 (483) 0.0546 (22) Berry et al (1997) 0.0835 (10 600) 0.0101 (54) Forest et al (1997) 0.0624 (500) 0.0277 (18) Haddow et al (1998) 0.0756 (3169) 0.0096 (48) Wheeler and Sinosich (1998) 0.0708 (673) 0.0237 (17) Tsukerman et al (1999) 0.0870 (11 659) 0.0041 (29) de Graaf et al (1999) 0.0724 (255) 0.0683 (37) Mean c 0.0824 (31 435) 0.0014 (502) AFP van Lith (1996) (13 series b ) 0.0378 (9093) 0.0059 (233) Berry et al (1997) 0.0493 (10 600) 0.0152 (53) Forest et al (1997) 0.0377 (500) 0.0175 (18) Tsukerman et al (1999) 0.0511 (13 477) 0.0235 (29) de Graaf et al (1999) 0.0376 (255) 0.0065 (37) Mean c 0.0467 (33 925) 0.0095 (370) uE 3 van Lith (1997) (6 series) 0.0315 (3329) 0.0449 (116) a Excluding Macintosh et al (1994) as later found to include data from other series in meta-analysis. b Excluding Forest et al (1995) as data included in Forest et al (1997).…”

“…We extended a previous meta-analysis of first-trimester PAPP-A and free -hCG (van Lith, 1996) and another for AFP and uE 3 (van Lith, 1997). These overviews, which used the same search strategy as adopted here, were brought up to date to include nine further first-trimester series (Scott et al, 1996;Krantz et al, 1996;Casals et al, 1996;Spencer et al, 1997;Berry et al, 1997;Haddow et al, 1998;Wheeler and Sinosich, 1998;Tsukerman et al, 1999;de Graaf et al, 1999) and a recent extended version of a previous series (Forest et al, 1997). For first-trimester PAPP-A, individual MOM values could be extracted from 12 of the series, including five from a pooled analysis (Cuckle, 1994) and one where a subset of results had been published separately (Hurley et al, 1993).…”

One-stop clinic for assessment of risk of chromosomal defects at 12 weeks of gestation

“…Additionally, each marker showed a small but significant negative correlation with maternal weight (PAPP-A, r = -0.278; free b-hCG, r = -0.146). After combining free b-hCG and PAPP-A with maternal age in mathematical models, it has been estimated that the detection rate of trisomy 21 is about 60% at a 5% screen-positive rate [43][44][45][46][47][48][49][50][51] .…”

First trimester serum concentrations of placental proteins in singleton and multiple IVF pregnancies: implications for Down syndrome screening

“…This protein was soon confirmed to be an excellent early pregnancy marker for this pathology [4,10,20]. In first trimester screening, besides PAPP-A the hCG molecule, or now mostly its free b subunit since it was found to be slightly superior to the intact dimeric molecule [28,29], are quantified. Hormonal stimulation may have a similar or higher impact on first than on second trimester marker levels as a consequence of the timing of the treatment before pregnancy arises.…”