Ultrasonographic Placental Thickness - Its Correlation to Gestational Age

Introduction: Placental growth and maturation with advancing pregnancy is essential for the healthy growth and development of foetus and a correlation between physical measurement of placenta and gestational age is not a very illogical expectation. The present study was undertaken with a view to find out if a correlation exists between gestational age and placental thickness. Aims and Objectives: 1) To study the correlation between placental thickness and gestational age of foetus.2) To determine normal ultrasonographical placental thickness for various gestational ages. Material and Methods: It was an observational study done at the Dept. of Obstetrics& Gynaecology, Dr. S. N. Medical College Jodhpur, Rajasthan. About 333 antenatal mothers with varying gestational ages from 11-40 weeks with known LMP, inclusion criteria satisfied& exclusion criteria verified were subjected to ultrasonographic examination and placental thickness is measured for mothers whose fetal biometry corresponds to LMP and the clinically assessed gestational age. Results: The mean values of placental thickness were calculated for different gestational ages from 11 - 40 weeks. It was observed that placental thickness gradually increased from 14.6 mm at 11 weeks to 38.9 mm at 40 weeks gestation. In our study, the mean placental thickness was slightly in the higher range for the corresponding gestational age up to 19 weeks. From 20 weeks to 36 weeks of gestation the placental thickness in mm almost matched with corresponding gestational age in weeks. After 36 weeks, placental thickness started decreasing by 0.5 to 1 mm to corresponding gestational age till 40 weeks. Conclusion: The measurement of placental thickness is an important parameter for estimation of fetal age. It is helpful in cases where the exact duration of pregnancy is not known where the placental thickness almost matches with gestational age. Including placental thickness into routine fetal biometry might improve pregnancy dating