A cross-sectional study of the correlation between placental thickness, gestational age, and foetal biometric...

Foetal Biometric Parameters (FBP)-based pregnancy dating is vital for monitoring foetal growth. However, the FBP measurements that provide the most reliable gestational age estimations are taken during the first and early second trimesters ultrasound scans, which are often missed in resource-limited settings, necessitating alternatives. This study examined correlations between placental thickness, gestational age, and FBP measurements among pregnant women in the second and third trimesters at Muhima District Hospital and Remera Health Centre in Rwanda.

A cross-sectional study was conducted on 138 pregnant women with singleton pregnancies dated between 14 and 40 weeks. Placental thickness was measured at the umbilical cord insertion level using ultrasound. Pearson's correlation and linear regression analyses were used to evaluate the relationship between placental thickness, gestational age, and foetal biometric parameters measurements.

A strong positive correlation was observed between placental thickness and gestational age (r = 0.976, p < 0.001). Significant correlations were also noted with biparietal diameter (r = 0.882), p < 0.001; head circumference (r = 0.952), p < 0.001; abdominal circumference (r = 0.967), p < 0.001; and femur length (r = 0.953), p < 0.001. The derived regression equation for gestational age estimation was PT = 0.1 + 1.05 × GA.

Placental thickness strongly correlates with gestational age and foetal biometric parameters, suggesting its potential as a supplementary tool for gestational age estimation. However, longitudinal studies in diverse populations are needed to validate these findings.

Incorporating placental thickness measurement into routine antenatal ultrasound protocols improves the accuracy of gestational age and delivery date estimation, especially when early scans are missed or the last menstrual period is unknown or unreliable for Naegele's rule-based estimations.