Placental 11B-Hydroxysteroid Dehydrogenase Type 2 mRNA Levels in Intrauterine Growth Restriction versus Small-for-Gestational-Age Fetuses

INTRODUCTION: The objective of this study was to evaluate placental 11B-hydroxysteroid dehydrogenase type 2 (11B-HSD-2) mRNA levels in intrauterine growth-restricted fetuses (IUGR) as compared with small-for-gestational-age (SGA) fetuses according to clinical criteria. MATERIAL AND METHODS: Placental levels of 11B-HSD-2 mRNA levels were measured in SGA (birth weight <10th centile) and gestational-age-matched, appropriate-for-gestational-age (AGA) births. SGA was classified as IUGR (birth weight <3rd centile or <10th percentile with abnormal uterine artery Doppler or cerebroplacental ratio) or non-IUGR SGA. After RNA extraction, mRNA levels were determined by reverse transcription and quantitative PCR. RESULTS: A total of 38 placentas were analyzed (20 AGA and 18 SGA). Among the SGA pregnancies, 13 qualified as IUGR. The activity of 11B-HSD-2 in IUGR pregnancies [0.105 (SD 0.328)] was significantly reduced compared to non-IUGR SGA [0.304 (SD 0.261); p = 0.018] and AGA [0.294 (SD 0.328); p = 0.001]. These differences remained significant after adjusting for potential confounders (such as smoking or maternal cortisol levels). Activity levels did not significantly differ between non-IUGR SGA and AGA. DISCUSSION: IUGR fetuses had reduced 11B-HSD-2 activity in comparison with SGA and normally grown fetuses. This finding provides opportunities to develop new placental biomarkers for the phenotypic characterization of fetal smallness.