A high cesarean section rate in China, particularly in recent years, could affect the new policy that allows all couples to have two children, according to obstetrics and gynecology experts.

After decades of a one-child policy, China adopted the second-child policy this year, and about 60 percent of the women now eligible are age 35 or older, government estimates show.

Pregnancy and baby delivery pose increasing health risks for mothers of that age as well as their newborns, said Li Kui, a professor of obstetrics and gynecology at Peking University First Hospital.

The babies of women in that age group are more susceptible to such conditions as Down syndrome and various birth defects, experts said. Miscarriage and complications during pregnancy also are more frequent for such high risk mothers.

If a woman's first child was delivered via C-section, "the mother faces greater risk when having a second," he said. The scarred uterus from a previous C-section might result in other conditions like placenta previa, in which the placenta lies in the lowest part of the womb and covers the cervix. Women with this problem are at higher risk of life-threatening massive bleeding, Li said.

Cheng Linan, honorary chairwoman of the Chinese Society of Family Planning, advised women who have had C-sections to wait a year or two before another pregnancy.

Pregnant women who expect a low-risk delivery, or those who have not previously had a C-section, won't deliver prematurely and are only carrying one baby in the correct position, should all have vaginal deliveries, Li said.

Currently, "a scarred uterus from previous surgery is the main reason for C-sections at our hospital," he said.

Health authorities in recent years have made great efforts to prevent unnecessary C-sections in China, he added. Currently, about 40 percent of the nation's newborns are delivered via C-section, Li said.

shanjuan@chinadaily.com.cn