How does an ultrasound produce an image of a fetus in the mother’s uterus?

Ultrasounds bounce inaudible sound waves off the solid structures in the body to create a 2D image.

The solid structures reflect sound waves, creating a white or gray appearance.

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the "dirty dozen" chemicals banned in an international treaty are formally known as persistent organic pollutants, or pops. the united nations environment program provided this background on what they are and what they can do to humans and wildlife.

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