A mother holds her child in front of a wall with photos of babies in Taizhou, Zhejiang province, Nov 17, 2013. Couples will be allowed to have two children if one of the parents is an only-child. Pan Kanjun / For China Daily

BEIJING - Ma Xiaoyi carefully puts away her son's clothes and toys, hoping she can soon fall pregnant and have a second child.

Even her five-year-old son Lin Xuan wants a brother or sister. "He often asks me when his little brother or sister will be born," said Ma, 34.

When his nursery school teacher tells the children to draw pictures for their family, Lin always writes on his work "to my would-be brother or sister".

Ma has kept every drawing. "They'll make a sweet present when the baby is old enough to read."

Ma's husband, Lin Maogeng, is a single child but she is not.

According to a change in family planning policy announced last week, urban couples like Ma and her husband Lin will soon be allowed to have two children -- as long as one of them is an only child.

Demographer Zhai Zhenwu said the new policy would make an estimated 15 million to 20 million couples eligible for a second child. It is a significant change to the country's family planning policy that has been prevalent for more than three decades.

About 50 to 60 percent of these couples are willing to have a second child, Zhai said, quoting a recent poll by National Health and Family Planning Commission.

Having grown up with an older brother, Ma believes having a sibling can help improve a child's personality and development.

"My brother is five years older than me. He was a caregiver, role model and friend when we were children." she said. "I never felt lonely, and our parents never worried about us when they were at work."

Today, Ma often risks being late for work as she has to take her son to nursery. She feels guilty when she has to work overtime and leave Lin with the nanny.

Ma, born in Dalian, a port city in northeast China's Liaoning Province, secured a job in Beijing after she graduated in journalism from university. "It's reassuring to think that my brother's family live only a few blocks away from my parents. Had I been the only child, it'd never have occurred to me to leave my parents."

What makes Ma want another child is the heartbreak she has witnessed, of older parents who have lost their only son or daughter.

For over a decade, her job as a journalist has taken her to sites of earthquakes and other natural disasters, senior nursing homes and hospitals. Ma has witnessed the agony and helplessness of bereaved parents. It upsets her.

"Talking about two children, most people complain about the high living costs and tuition. But if you have witnessed the pains of those bereaved parents, you'd stop worrying about the burdens a second child brings."

Many of Ma's high income peers already have a second child, and have paid a fine of about 300,000 yuan. But for Ma and her husband, both government employees, to violate the family planning policy would have cost them their jobs.

Yang Zhizhu, a former teacher in Beijing, was fired after his wife gave birth to their second child in December 2009. The couple have two girls.

Yang, who taught civil law at China Youth University for Political Sciences, insisted he would safeguard his younger daughters' "right of existence" and refused to pay any fine. He is now an activist calling for the abolition of the family planning policy.

"The new policy change is far from enough to offset China's aging problem," Yang said on his Weibo.com microblogging account. "The country needs to scrap its restrictions on childbirth as soon as possible."