Placental thickness in normal singleton pregnancies: correlation with gestational age and variation by implantation site in Kano, Nigeria

Abstract

Placental thickness (PT) is a simple sonographic parameter that reflects placental growth and functional integrity. Published literature presents inconsistent findings regarding the influence of placental implantation site on measured thickness. Objective: This study aimed to sonographically assess the relationship between PT and gestational age (GA), and to determine the variation in thickness according to placental location in normal singleton pregnancies. Methodology: A prospective cross-sectional study was conducted involving 381 pregnant women in the second and third trimesters attending antenatal clinics in Kano, Nigeria. Transabdominal ultrasound examinations were performed, and PT was measured at the level of umbilical cord insertion. Placental location and fetal biometric parameters were documented. Statistical analyses comprised descriptive statistics, Pearson correlation, and one-way ANOVA, with statistical significance defined as p < 0.05. Results: PT exhibited a moderate positive correlation with GA (r = 0.50, p < 0.001). Statistically significant variations in PT were noted across different placental locations (F = 6.46, p < 0.001). The postero-fundal and fundal placentas showed the highest average thickness values (3.69 cm and 3.49 cm, respectively), whereas anterior placentas had the lowest thickness (3.19 cm), indicating a mean difference of about 0.5 cm, which could affect the clinical interpretation of PT
measurements. Conclusion: PT increases progressively with advancing GA and varies significantly depending on implantation site. Placental location should be considered when interpreting PT measurements during routine obstetric ultrasound examinations.