More than 30 percent of women in Japan are worried about how they will be viewed by their bosses as well as by colleagues at work when taking maternity leave, a survey showed Thursday.

The finding by the foundation supporting families and children comes at a time when Japan is tackling a declining birthrate and shrinking population. The annual number of newborns fell below the 1 million mark for the first time last year.

"It is necessary to create an environment where people can choose various ways of working," said Kai Akiyama, executive director of the foundation, 1 More Baby Oendan (Supporters), which provides information on raising children.

The online multiple choice questionnaire in April that covered 529 working mothers aged between 20 and 39 asked what worries respondents when taking maternity or subsequent childcare leave.

The reaction of their bosses was the top source of such concern, cited by 37.6 percent, followed by how they will be viewed by colleagues at 32.4 percent. About 30 percent also cited an atmosphere in the office that discourages them from taking childcare leave in quick succession.

On ideal conditions that respondents consider important for taking childcare leave, 42.3 percent picked wanting to feel they will not face problems securing a slot in competitive daycare facilities in Japan.

That response was followed by 37.9 percent citing feeling they can extend childcare leave if they cannot secure a daycare slot while 32.7 percent wanted not to fear a negative impact on their career when they return from childcare leave.

As for factors respondents viewed as important when they work from home, 33.0 percent cited the use of daycare centers, 26.1 percent their bosses or colleagues being cooperative with that style of working and 22.4 percent seeking an atmosphere that encourages telecommuting.

Under Japanese law, mothers can leave work for a combined period of 14 weeks before and after delivery and may take childcare leave until their babies turn 1, which could be extended for such reasons as failure to secure daycare services.