Rail companies in Tokyo are handing out badges to pregnant women in the hope they prompt commuters to give up their seats on the capital's crowded trains.
Pregnant women have welcomed the move
The badges come in pink and blue and have the words "There is a baby in my stomach" printed on them.
Health officials said people sometimes could not tell if a woman was pregnant, especially in the early stages.
Japan is worried about a population decline and is seeking ways to make pregnancy and having children easier.
Rail officials have been handing out the badges at stations since 1 August.
One commuter welcomed the initiative.
"When I was three months pregnant and got on the train, no-one would really notice me and I couldn't really ask them to give me a seat," Yoshiko Kato told Reuters news agency.
Japan's fertility rate has continued to fall in recent years, hitting a new low in June.
Officials have predicted a serious effect on the economy and have introduced a variety of initiatives to persuade women to have more children.
These have included expanding child-care facilities, improving employment conditions for mothers and even government-sponsored speed-dating.