Background: The placenta plays important nutritional, metabolic and endocrine roles that ensure proper foetal growth and development. Since placental growth occurs throughout pregnancy, its measurement can be correlated with the growth of the foetus. This study determines the relationship between placenta thickness and foetal growth. Methods: Four hundred and twenty healthy singleton pregnancies were sonographically examined between 15 and 40 weeks gestation at the Radiology Department of the University of Benin Teaching Hospital Benin-City. Placental thickness was measured perpendicularly at the level of cord insertion. The measurements were correlated with foetal gestational ages obtained from the crown rump length, biparietal diameter and femur length. Results: The age range of study subjects was 18-43 years (mean 29.2+1.6 years). Their parity ranged from 0-7 (mean: 1.50+1.6). Placenta thickness ranged from 26.6 ±2.51 mm at 15 weeks to 39.2 + 5.69 mm at 40 weeks. There was linearity of measurements throughout gestation. Pearson′s correlation analysis showed a coefficient of +0.632 between placental thickness and gestational age. There was a statically significant association between placental thickness and gestational age (P=0.000), and between estimated gestational age and foetal biomedical parameters, (p=0.000). Conclusion: Our data demonstrate a relationship between placental thickness and estimated foetal gestational age. However, more longitudinal studies are recommended to support these observations.