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Co‐variables in first trimester maternal serum screening
Author(s) -
de Graaf Irene M.,
Cuckle Howard S.,
Pajkrt Eva,
Leschot Nico J.,
Bleker Otto P.,
van Lith Jan M. M.
Publication year - 2000
Publication title -
prenatal diagnosis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.956
H-Index - 97
eISSN - 1097-0223
pISSN - 0197-3851
DOI - 10.1002/(sici)1097-0223(200003)20:3<186::aid-pd776>3.0.co;2-a
Subject(s) - pregnancy associated plasma protein a , medicine , gestation , pregnancy , obstetrics , parity (physics) , fetus , down syndrome , trisomy , birth weight , gestational age , statistical significance , gynecology , first trimester , biology , physics , particle physics , psychiatry , genetics
The objective of this study was to determined the influence of maternal weight, maternal smoking habits, gravidity, parity and fetal gender on the level of maternal serum marker used in first trimester screening for Down syndrome. A total of 2449 singleton unaffected pregnancies from two centres were studied. Maternal serum free β‐human chorionic gonadotrophin (hCG) and α‐fetoprotein (AFP) concentrations had been measured in all pregnancies, and pregnancy associated plasma protein (PAPP)‐A levels had been measured in 924. All results were expressed as multiples of the gestation specific median (MoM) values after regression, using each centre's own medians. Information on maternal weight was available in 2259 pregnancies, on self‐reported current cigarette smoking in 1364 (of whom 117 (8.6%) were smokers), on gravidity in 1371, parity in 1303 and fetal gender in 253. All three markers showed a statistically significant negative association with maternal weight ( p <0.0005) and in the subsequent analyses MoM values were weight adjusted using standard methods. The median PAPP‐A level in smokers was 0.81 MoM, a significant reduction ( p <0.005); free β‐hCG was also reduced (median 0.89 MoM) but not significantly ( p =0.17), and AFP was unaltered. The median AFP level in primagravidas was highly significantly greater than that in gravid women ( p <0.0005). In PAPP‐A the reverse effect was seen but it did not reach statistical significance ( p =0.15) and there was no effect for free β‐hCG. Results of a similar magnitude and direction were found for parity. The median level of free β‐hCG was higher ( p =0.0005), and the median AFP lower in female pregnancies. Maternal weight and, for PAPP‐A, maternal smoking are important first trimester screening co‐variables. Gravidity, parity and fetal gender also seem to influence one or more first trimester markers. Copyright © 2000 John Wiley & Sons, Ltd.