association between papp-a and placental thickness

background: measuring of maternal serum pregnancy-associated plasma protein-a (papp-a) in first trimester can be a way for early detection of adverse prenatal outcome due to faulty placenta.objective: the aim was to determination of association between placental thickness in second trimester with low level of papp-a in first trimester.materials and methods: in this cohort study, serum papp-a of 187 pregnant women was measured in the first trimester of pregnancy. patients who had papp-a ≤0.8 mom were in exposed and others who had papp-a >0.8 defined as unexposed group. the criteria of placental thickness in ultrasound study was thickness of 4 cm or more than 50% of placental length.results: of 187 patients, 87 patients had papp-a >0.8 and 93 patients had papp-a ≤0.8. women with low levels of papp-a in the first trimester, had an increased incidence placental thickness of 34.4%, whereas another group had about 15% (p=0.002). also, papp-a levels had acceptable sensitivity and specificity for placental thickness detection (71.1% and 54.8%, respectively.conclusion: our study showed that serum level of papp-a generally was low (≤0.8) in women with a thick placenta (>4 cm or >50% of placental length). the first trimester of pregnancy measurement of papp-a will be more predictable for healthy placenta.