Students learn in microeconomics that the demand curve for a good, which shows the relationship between the price of a good and the quantity of the good that consumers demand-i.e. are willing, ready, and able to purchase-has a negative slope.
The UNICEF estimates that an average of 353,000 babies are born each day around the world. The crude birth rate is 18.9 births per 1,000 population or 255 births globally per minute or 4.3 births every second (as of Dec. 2013 estimate).
According to the March of Dimes, neural tube defects happen in about 3,000 pregnancies each year in the United States. About 1,500 babies are born in the U.S. with spina bifida, the most common NTD, according to the National Institute of Child Health and Human Development.