Ultrasound measurement of foetal head to abdomen circumference ratio in pregnant Nigerians.

The ratio of foetal head to abdomen circumference ratio has been established in 242 foetuses scanned between 16 weeks and 40 weeks of gestation. The ratio was observed to fall gradually from 1.30 at 16 weeks to 1 at 30-32 weeks, and more slowly thereafter to 0.95 at term. The value of this ratio in differentiating between symmetrical and asymmetrical growth-retarded foetuses and in the management of such pregnancies is discussed.