In the early 1970s American women gave birth, on average, to 2.12 children each. By 2018 that number had fallen to 1.73. Jordan Nickerson and David Solomon, professors at MIT, think they have found an interesting factor which help explain this change: America’s increasingly protective child car-seat laws.
Their study examines the effect that car-seat policies may have had on American birth rates. During the 1980s, only the children aged under three had to be secured in child-safety seats. But since then, the requirements have been slowly increased. Today, most places in America make children sit in safety seats until their eighth birthdays. That concern for youngsters’ safety has had the unexpected consequence of fewer three-child families.
In drawing this conclusion they have connected population data with changes in state laws on safety seats. They discovered that stricter laws had no noticeable effects on the rates of births of first and second children, but with a drop, on average, of 0.73 percentage points in the number of women giving birth to a third while the first two were young enough to need safety seats.
The professors also made two other related observations. The reduction they saw was limited to families that did actually have access to a car. And space in the vehicle is the important factor. In pre-safety-seat days, putting three young children into the back of a family car was a perfectly practical advice. Most such cars, though, can comfortably accommodate only two safety seats. So, as the child car-seat laws change, a family must wait longer time for a third child to fit in the car. Sometimes, that wait will mean no third child is ever born.
Unless, of course, the family concerned buys a bigger car. But average families have the obvious reasons not to do so — big cars cost more, and are more costly to run. Interestingly, Dr Nickerson and Dr Solomon found that the third-child deterrent (遏制作用) appears even stronger among wealthier families. As they observe, “large cars may reflect their real status and taste, which may make people unwilling to switch even when they can afford to.”
12. What is the passage mainly about?
A.Changes in American car-seat laws. |
B.Ways to ensure children’s safety in cars. |
C.Influence of car-seat laws on American birthrate. |
D.The connection between cars and American birthrate. |
13. What contributes to fewer three-child families according to Paragraph 4?
A.The space of the family car. | B.The family’s economic status. |
C.The quality of child safety seats. | D.The desire to have a third child. |
14. What can be inferred about big cars from the last paragraph?
A.They are a symbol of wealth. |
B.They are affordable to most families. |
C.They are more popular among richer families. |
D.They are unable to solve child birth rates problem. |
15. How did the two professors reach the conclusion of their study?
A.By comparing data. | B.By making surveys. |
C.By doing experiments. | D.By holding interviews. |