The premarital checkup rate in China increased to nearly 60 percent of all new couples in 2016, after a series of measures taken in recent years to encourage the exams as a way to help reduce birth defects, China's top health authority said.

In 2016, 59.7 percent of all couples who married in China had a premarital checkup, with diseases spotted in more than 930,000 people that could affect birth, the National Health and Family Planning Commission wrote in response to written questions from China Daily.

Premarital checkups, which target diseases that could affect the health of couples or their offspring, can help with early diagnosis and treatment and to promote reproductive health, reduce birth defects and improve the population's overall health, the commission said.

Premarital checkup rates declined sharply in China once the exams became voluntary with the adoption of a new regulation in 2003. The rate declined to 2.9 percent in 2005 and rebounded to 41 percent in 2011 and to 48.4 percent in 2012, figures previously released by the commission showed.

Birth defects had increased amid a declining rate of premarital checkups, records show. The incidence of congenital heart diseases in China in 2011 was 3.56 times that in 2000, according to a report released by the commission in 2012.

Qin Geng, chief of maternal and child health at the commission, said the number of babies born with defects every year in China was estimated at 900,000.

With the adoption of the universal second-child policy since the start of 2016, a rising number of couples are trying to have a child, including groups considered to have higher risks such as women older than 35. Some medical experts have called for more ways to encourage checkups to reduce health risks for both women and children.

Of the 90 million women eligible to have a second baby, 60 percent are 35 or older, according to the national commission.

Liu Wenxian, a cardiologist at Anzhen Hospital in Beijing, said that with the policy an increasing number of women with risky conditions, such as cardiovascular disease, are giving birth at hospitals.

"Some of them are in such serious condition that we advise them not to put their health at risk and have a baby likely to have birth defects," he said. "We recommend all couples have a checkup before marriage and pregnancy, although it is no longer mandatory."

In recent years, the commission has increased investment in promoting premarital checkups. It launched a pilot project in 2012 that includes free premarital checkups that initially covered the Guangxi Zhuang autonomous region and Hainan and Yunnan provinces, it said.

The project, aimed at reducing the incidence of Mediterranean anemia, an inherited blood disease that can be fatal for children, had covered 10 provinces, municipalities and autonomous regions in southern China that are more severely hit by the disease, the commission said.

With financial support from local governments, residents in 18 provinces, municipalities and autonomous regions, including Beijing, Shanghai, Anhui and Hunan, can now undergo free premarital checkups, it said.

Through promotional efforts in other areas, such as the Guangxi Zhuang autonomous region and Fujian province, the premarital exam rate has risen to more than 90 percent, the commission said.

In Beijing, the rate declined from 100 percent in 2003 to as low as 5 percent in subsequent years, and rebounded to about 10 percent in 2016 after various promotional efforts, according to the Beijing Commission of Health and Family Planning.

Nationwide, major conditions covered by premarital checkups include inherited diseases, certain infectious diseases and mental diseases such as schizophrenia, according to a regulation released by the commission.

HIV tests are not mandatory, but local governments can decide whether to include them in their checkup programs, the regulation said.