The use of prenatal ultrasound has become controversial as it is increasingly being performed for business and social interests rather than for medical use. This nonmedical use of the modality has violated the US FDA guideline. Ultrasound scans have been proven to increase temperature in insonated tissue and their effects have been investigated via phantom and animal experiments. Absorption coefficient of the bone is the highest compared with any other structure. Thus, exposure to ultrasound, especially during osteogenesis, can cause significant damage to developing foetus. Twenty-two pregnant does of known gestation were enrolled in the control and experimental groups. No exposure was given to the control group while the experimental groups were exposed accordingly to the prenatal ultrasound in the 1st, 2nd and 3rd stage for 30, 60 and 90 minutes respectively. A total of 142 subjects aged between 1 and 5 months were analysed for bone strength. The Tb.Th of the experimental group was reduced significantly as compared to the control group. Po, TMD and empty lacunae were higher in the experimental group. It is thus concluded that one-time prenatal ultrasound can affect bone strength in young subjects.