Photo/IllutrationNurses ask for signatures for a petition to improve working conditions in Kofu in May 2016. (Asahi Shimbun file photo)

Around half of pregnant nurses are being put at risk of miscarrying or giving birth early because of working night shifts, according to a survey by the Japan Federation of Medical Workers’ Unions.

Chronic understaffing is the major reason that only about 50 percent of pregnant nurses were exempted from working at night, federation officials said.

“It is necessary to improve working environments by taking measures such as increasing the number of staff,” an official said.

The federation conducts the survey every four to five years to investigate nursing staff’s working conditions.

Of about 33,000 workers who responded to the latest survey in May, 3,301 got pregnant after 2014.

Only 26 percent of those nurses reported being in good condition during pregnancy. Thirty-five percent said they experienced premature births or symptoms of miscarriages, and 10 percent had miscarriages.

The results compare unfavorably with another survey from 2015 conducted on working women in various professions by the National Confederation of Trade Unions (Zenroren).

While about 34 percent of respondents to that survey said their conditions were good when pregnant, about 27 percent had premature births or symptoms of miscarriages.