Ultrasound and endocrinological markers of first trimester placentation and subsequent fetal size.

INTRODUCTION

To study the relationship between 2-dimensional placental ultrasound measurements and maternal serum (MS) levels of biomarkers of placentation and in pregnancies presenting with an isolated abnormally high or low birthweight at term, without evidence of placental insufficiency.

METHOD: We performed a population based cohort study of 306 pregnancies delivered at term including 30 presenting with large-for-gestational age (LGA, birthweight > 90th centile) and 17 small-for-gestational age (SGA; birthweight < 10th centile). Antenatal measurements included placental thickness and 2D-volume and MS levels of pregnancy-associated plasma protein A (PAPP-A) and free-beta human chorionic gonadotrophin (fβhCG) at 11-13(+6) weeks of gestation and mid-trimester MS α-fetoprotein (AFP), unconjugated estriol (uE3) and inhibin A levels.

RESULTS

In the subgroup with a normal birthweight (10th-90th centile), there was a significant positive correlation between birthweight and the basal plate surface area (p < 0.001) and 2D placental volume (p < 0.01). In the LGA subgroup, MS PAPP-A was significantly (p < 0.05) higher than in normal controls and there was a significant (p < 0.01) positive correlation with birthweight. There was no significant difference for any of the ultrasound and biomarkers parameters between SGA and the normally grown controls.

DISCUSSION: In uncomplicated singleton pregnancies with a normal birthweight, 2D measurements of placentation are related with fetal size but are not related to subsequent excessive or slow fetal growth. LGA at birth is associated with increased MS PAPP-A at 11-14 weeks of gestation supporting the association between PAPP-A synthesis and early placental growth and development.