PAPP‐A and free β‐hCG measured prior to 10 weeks is associated with preterm delivery and small‐for‐gestational‐age infants

Abstract

To evaluate whether measuring pregnancy-associated plasma protein A (PAPP-A) and free β-human chorionic gonadotrophin (β-hCG) before 10 weeks of gestation affect the association between these biomarkers and adverse pregnancy outcomes. Singleton pregnant women (9450) who attended the prenatal screening program, Aarhus University Hospital, Denmark, were included. Maternal serum levels of PAPP-A and free β-hCG were measured between week 8 and 13 weeks and 6 days. The risk of preterm delivery (<37 weeks) and small for gestational age (SGA) (<the fifth centile) was evaluated in relation to PAPP-A and free β-hCG < 0.4 multiples of the median, stratified according to early (<10 weeks) or late (≥ 10 weeks) biochemical testing. A stronger association between low PAPP-A and SGA was found with early serum sampling compared to late, but the difference was not statistically significant [odds ratio (OR) 3.2 vs 1.8; P value = 0.11]. This difference did not apply to PAPP-A and preterm delivery. For free β-hCG, a stronger association with preterm delivery was found with early testing (OR 1.9 vs 1.1; P value = 0.31), whereas this difference was not found regarding SGA. Biochemical testing before 10 weeks does not affect the association between low PAPP-A and free β-hCG and adverse pregnancy outcomes. Whether the association is actually stronger with early testing, requires further study.