Question 1
Question 2
Ask unlimited questions for free
The first-known contraceptive was crocodile dung, used in Egypt in 2000 BC. Condoms were also reportedly used, made of animal bladders or intestines.
Approximately 500,000 babies are born each year in the United States to teenage mothers.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
The familiar sounds of your heart are made by the heart's valves as they open and close.
People about to have surgery must tell their health care providers about all supplements they take.
For a complete list of videos, visit our video library