Jaana Nevalainen

Objectives To evaluate different cut-off values of first trimester pregnancy associated plasma protein-A (PAPP-A) in screening for adverse pregnancy outcomes in a retrospective cohort study. Methods During the study period of 1.1.2014–31.12.2018, total of 23,482 women with singleton pregnancies participated in first trimester combined screening for chromosomal abnormalities. Maternal serum PAPP-A multiple of medians (MoM) levels were measured, and study population was divided into three study groups of PAPP-A ≤0.40 (n=1,030), ≤0.35 (n=630) and ≤0.30 (n=363) MoM. Results Small for gestational age (SGA), preterm birth (PTB) and composite outcome (SGA, hypertensive disorder of pregnancy (HDP) and/or PTB) were more frequent in all three PAPP-A MoM study groups and pre-eclampsia in ≤0.40 and ≤0.35 study groups than in their control groups (p < 0.05). The odds ratio (OR) for SGA varied from 3.7 to 5.4 and sensitivity and specificity from 6.9 to 13.8% and from 95.9 to 98.6%, between study groups. Using PAPP-A ≤0.30 MoM as a screening cut-off instead of PAPP-A ≤0.40 MoM, resulted in approximately 50% reduction in screening detection of SGA and PTB. Conclusions PAPP-A ≤0.40 MoM should be considered as a primary screening cut-off for adverse pregnancy outcomes as approximately 23% will develop either SGA, HDP or PTB. It seems to be the best cut-off to screen for SGA.