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

The low level of pregnancy-associated plasma protein A (PAPP-A) has relationship with unfavorable outcomes in neonates. We aimed to evaluate the association between thickness and size of placenta in singleton pregnant women.

In this prospective cohort study, we investigated 102 women in 18-23 weeks and PAPP-A level at gestational age in 11 to 14 weeks with 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 exposed group and others to non-exposed group. Placental thickness and size were assessed during second trimester by ultrasound examination and described as abnormal high thickness if the thickness was > 4 cm or more than 50% of placental length and abnormally small size when the maximum length was < 10 cm. Then, placental thickness and size of the two groups were compared.

Sixty-eight patients had PAPP-A >0.5 and 34 patients had PAPP-A ≤0.5. 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 in another group was 12 and 7 cases, respectively (P=0.023). The sensitivity and specificity of PAPP-A.

Based on the results, the size and thicknesses of placenta in women with a low level of PAPP-A (≤0.5) were abnormal.