Expectant women have to exhale with added force to get vocal cords to vibrate and get the sound out. That reduced flexibility can make it trickier to hit high notes, so some pregnant singers avoid them altogether. Actually, one of Dr. Kwak’s patients, an opera singer, has not noticed any difference in vocal quality while pregnant. In menopause, estrogen levels plummet as levels of androgens, male sex hormones, rise, which can lead to swollen vocal cords. Those kinds of changes can also affect a pregnant woman if she breast-feeds after giving birth.

Source: New York Times February 23, 2017 18:19 UTC