Old superstitions die hard – and in South Korea, beliefs in astrology remain so strong in that fertility rates plummeted and thousands of abortions were performed in 2002 because parents didn’t want to give birth to a daughter in the dreaded Year of the Horse.

To South Koreans, the Year of the Horse is viewed as a particularly bad time to have a girl, Jungmin Lee and Myungho Paik report in the latest issue of Demography. Koreans, as well as people in several other Asian countries, have believed since antiquity that each person is destined to possess certain characteristics depending on where his or her birth year falls in the 12-year astrological cycle.

These beliefs are still so deeply held that couples delay having children in a horse year, induce abortions if they believe their baby will be a girl or deliberately misreport their daughter’s birth year, the researchers found.

Between 1970 and 2003, the overall fertility rate dropped by about 8.9 percent in South Korea in the horse years of 1978, 1990 and 2002, only to quickly rebound, wrote Lee, who teaches at the University of Arkansas, and Paik, a graduate student at the University of Texas. In 2002, fertility declined by 7.5 percent.

“The decrease in fertility in 2002 is, by and large, due to birth timing,” they found. There are approximately 29,900 missing girls or female pregnancies: 86 percent by birth timing, 3 percent by misreporting and 11 percent by abortion – a positive sign, these authors suggest, since more than 20 percent of the fertility decline in 1990 was due to parents deciding to abort female fetuses.