MONDAY, Sept. 29, 2003 (HealthDayNews) -- Difficult economic conditions in a country may result in fewer male than female births, says a study from the University of California, Berkeley.
Ralph Catalano, a professor of health policy and management, found a link between economic problems and a decline in male births in East Germany. His study appears in the September issue of Human Reproduction.
Catalano analyzed birth records in West and East Germany from 1946 to 1999. In 1991, the ratio of male to female births in East Germany dropped to its lowest levels since World War II. He found there were about 800 fewer male births than expected.
In 1991, East Germany was adjusting from the collapse of Communism and making the transition to a free market economy.
"There has been a longstanding theory in biology that says stressed populations yield fewer males than otherwise expected," Catalano says in a news statement.
"It's a phenomenon that has been reported in herd animals responding to famine or drought. The change in the ratio of male to female births in Germany suggests that similar mechanisms may be at work in humans," he says.
This reduced male birth rate has been seen in other cases where a human population is under stress. For example, there was a temporary decline in male births after the 1995 earthquake that hit Kobe, Japan.
Catalano says his study is the first to analyze human sex ratios over a long period of time. But he cautions that his findings about East Germany may not be definitive.
"What happened in East Germany is so unusual, it may not be applicable to other situations. The people were experiencing economic stress, but they were also grappling with dramatic cultural, political and societal changes as well," he says.
Here's where you can learn more about the U.S. birth rate.