Abstract

Background: Accurate determination of gestational age is essential for prenatal care, guiding pregnancy monitoring and management. Although ultrasonographic fetal biometry is the standard method for estimating gestational age, its accuracy decreases with advancing gestation, variations in fetal position, and fetal anomalies. Adequate placental growth is essential for optimal fetal development. This study aimed to evaluate placental thickness using ultrasound to estimate gestational age. Methods: This cross-sectional study, conducted between December 2024 and April 2025 at Kilimanjaro Christian Medical Centre, included 206 pregnant women with gestational ages of 14–40 weeks. Placental thickness was measured at the level of the umbilical cord insertion using a 3.5–5 MHz ultrasound transducer. Standard fetal biometric parameters, including head circumference, biparietal diameter, abdominal circumference, and femur length, were recorded. Data were analyzed using SPSS version 25 with Pearson’s correlation, regression analysis, and analysis of variance.
Results: The mean maternal age was 31 years, with most participants aged 26–34 years. The majority were multiparous (61.2%), had regular menstrual cycles (77.2%), and over half had a body mass index ≥ 30. Placental locations were anterior (48.1%), posterior (34%), fundal (14.1%), and lateral (3.9%). Placental thickness strongly correlated with gestational age (r = 0.960, p < 0.001) and all fetal biometric parameters. Regression analysis indicated high coefficients of determination (R² = 0.898–0.913, p < 0.001). Anterior placentas were, on average, 2.9 mm thicker than posterior placentas.
Conclusion: Placental thickness may serve as a reliable parameter for estimating gestational age in the second and third trimesters.

Key words: Ultrasonography, placenta thickness, gestational age estimation, second trimester, third trimester pregnancy