The Relationship between the Level of Pregnancy-Associated Plasma Protein A and Placenta Size and Thickness

Abstract

Background: The low level of pregnancy-associated plasma protein A (PAPP-A) has a relationship with unfavorable outcomes in neonates. This study aimed to evaluate the association between the thickness and size of the placenta in singleton pregnant women. Materials and Methods: In this prospective cohort study, 102 women were investigated in 18-23 weeks and PAPP-A level at the gestational age in 11-14 weeks with a singleton pregnancy who referred to Al-Zahra Hospital, Rasht, Iran, between 2017 and 2018. Serum PAPP-A of pregnant women was measured in the first trimester of pregnancy. Patients who had PAPP-A ≤ 0.5 Multiple of the Median (MOM (were dedicated to an exposed group and others to a non-exposed group. Placental thickness and size were assessed during the second trimester by ultrasound examination and described as abnormal high thickness if the thickness was > 4 cm or more than 50% of the placental length and abnormally small size when the maximum length was < 10 cm. Then, placental thickness and size were compared between the two groups. Results: PAPP-A levels of > 0.5 and ≤ 0.5 were recorded in 60 and 34 patients, respectively. Women with low levels of PAPP-A in the first trimester had an increased incidence of abnormal placental thickness in 13 cases and small placental size in 7 cases, whereas this number was 12 and 7 cases, respectively, in the other group (P = 0.023). The sensitivity and specificity of PAPP-A < 0.55 were 72.3 and 56% for abnormal placental thickness, respectively; the sensitivity and specificity of PAPP-A < 0.55 were 69.3 and 57.1%, respectively, in the assessment of abnormal placenta size. Conclusion Based on the results, the size and thicknesses of the placenta were abnormal in women with a low level of PAPP-A (≤ 0.5).