BEIJING - About 5.6 percent of newborns in China have birth defects, with about 900,000 affected infants born each year, according to a Ministry of Health report.

Birth defects have become the second-greatest cause of infant deaths in China, accounting for 19.1 percent of infant deaths, says the report on the prevention and treatment of newborn defects for 2012, issued by the ministry on Wednesday.

Of the babies born with defects, about 30 percent die within 5 years after birth, while another 40 percent suffer lifelong deformities, the report says. About 250,000 newborns have visible defects, it says.

Experts believe the increase in birth defects may be linked to the withdrawal of compulsory premarital health checks in 2003, as well as an increase in the number of women who have their first child at an older age.

The intake of prohibited medicine, increased exposure to radioactivity and drinking have also contributed to the increase, experts say.

Although the percentage of couples who went in for premarital health checks was at a mere 2.67 percent in 2004, it shot up to 41 percent in 2011 after several provinces began providing the service for free or requiring it in order to obtain a marriage license, the report says.

Birth defects are a serious problem in China, particularly in rural areas. Neural tube defects, congenital heart disease, cleft lip and hydrocephalus are among the most common defects.

To curb birth defects, authorities launched a health program in 2009 to provide free folic acid supplements for 12 million rural women of child-bearing age to help prevent birth defects.

World Health Organization statistics indicate that more than 7.9 million children, or about 6 percent of total births worldwide, are born with birth defects each year due to genetic or environmental causes.

Birth defects refer to physical, functional or metabolic abnormalities developed at or before birth.