Fetal Gestational Age Determination Using Ultrasound Placental Thickness In Tertiary Care Hospital Of Central India

Background: Accurate determination of fetal gestational age is essential for monitoring fetal growth, scheduling antenatal investigations and planning obstetric management. Gestational age is commonly estimated from the last menstrual period and conventional fetal biometric measurements. However, these methods may be less reliable when menstrual dates are uncertain or fetal biometric measurements are technically difficult. Ultrasonographic placental thickness may provide an additional simple parameter for estimating gestational age.Aim: To determine fetal gestational age using ultrasonographic placental thickness and assess its correlation with gestational age calculated from the last menstrual period and standard fetal biometric parameters.Materials and Methods: This hospital-based analytical cross-sectional study included 400 pregnant women with normal singleton pregnancies between 15 and 40 weeks of gestation who were referred for routine obstetric ultrasonography at People’s Hospital, Bhopal. Data were collected from 1 April 2024 to 31 December 2025 through consecutive sampling. Ultrasonography was performed using Siemens ACUSON NX2 or Voluson S6 machines. Fetal biparietal diameter, femur length and abdominal circumference were recorded, followed by measurement of placental thickness in millimetres at the level of umbilical cord insertion. Gestational age was estimated by fetal biometry and the last menstrual period. Results: The mean maternal age was 27.89 ± 3.34 years, and 48.25% of participants were aged 18–25 years. Second gravida women constituted the largest parity group at 43.00%. Placental thickness increased progressively from 15.61 ± 0.49 mm at 15 weeks to 39.69 ± 0.81 mm at 40 weeks. The overall correlation between placental thickness and gestational age was strong and statistically significant (r = 0.909, p < 0.00001). Based on fetal biometry, correlation coefficients were 0.884 in the second trimester and 0.998 in the third trimester. Based on the last menstrual period, the corresponding correlations were 0.754 and 0.995, respectively, with all associations being statistically significant.Conclusion: Placental thickness increased consistently with advancing gestational age and showed a strong positive correlation with gestational age estimated by fetal biometry and the last menstrual period. Ultrasonographic placental thickness may therefore serve as a simple, reliable and useful supplementary parameter for fetal gestational-age assessment, particularly during the third trimester