FETAL ADRENAL GLAND BIOMETRY: A POTENTIAL PREDICTOR OF PRETERM BIRTH

Background: Preterm birth is an important challenge in obstetrics and contemporary perinatology in India. Timely recognition, intervention and appropriate management is integral in curbing the upsurge in its incidence and consequent poor perinatal outcome. This study was conducted taking into account the potential mechanism of preterm labor: premature activation of the placental-adrenal endocrine axis wherein elevation of maternal cortisol leads to an increased production of placental corticotrophin releasing hormone which causes an increase in dehydroepiandrosterone produced by the fetal zone of the adrenal gland and its enlargement. This activates a cascade leading to early loss of uterine quiescence, consequently causing cervical modelling, ripening and preterm birth. Aim and Objectives: To assess fetal adrenal gland volume and fetal zone enlargement on ultrasound and evaluate its efficacy in the prediction of preterm birth.  Methods: This was a hospital based prospective study in which pregnant women with an uncomplicated live singleton pregnancy between 28 to 34 weeks of gestation were subjected to obstetric ultrasonography wherein fetal adrenal gland volume and fetal zone enlargement was measured. They were then followed up until their delivery, whether term or preterm and its correlation with fetal adrenal gland parameters was assessed.   Result: Corrected fetal adrenal gland volume showed the highest sensitivity of 90.0% and a specificity of 96.7% with a cut off value of 632.50 mm3/kg while fetal zone enlargement showed a sensitivity and specificity of 72.7% and 60.9% respectively.  Conclusion: This study concludes that fetal adrenal gland biometry can be used as a noninvasive, cost effective and potential new marker for the prediction of preterm birth.