The Year of the Goat is the cause for a slight decline in the number of newborns in 2015 over previous year, said nation's top health authority.

China had 16.55 million babies born last year, 320,000 fewer than 2014, the Year of the Horse, according to the National Bureau of Statistics.

China began to allow couples with one side being an only child to have a second child in late 2013, which made 11 million couples eligible.

Experts expected back then the policy would bring one million more babies compared with 2014.

Facing the slight decrease last year, some said the policy change could hardly reverse a downward trend of the population.

The National Health and Family Planning Commission, in response, rejected that view in an online statement issued on Wednesday.

The decline is due to the Year of the Goat and the decreasing women of childbearing age, it said.

There is an old Chinese saying "十羊九不全 (shi yang jiu bu quan)", that means nine out of 10 people born in the Year of the Goat are unlucky and will suffer from great misfortune throughout their life.

After that the Year of the Goat, China is expected to welcome 17.5 to 21 million newborns annually in five years, it projected.

In 2015, the number of women aged 15 to 49, deemed to be of childbearing age, fell by five million over 2014.

The group between 20 and 29 years old, considered the reproductive prime, has declined by 1.5 million.