South Korea installs an alert system on subway cars encouraging passengers to give up their seats to expectant mothers on busy commuter trains.

This technology could make riding the subway a nicer experience for pregnant women.

New smart devices have been installed on South Korean trains as part of the Pink Light campaign.

The devices detect a small sensor called a beacon, that expectant moms carry on their bags. When they are within 2 meters of priority seating, a pink light illuminates, letting passengers know a pregnant woman aboard needs a seat.

35-year-old South Korean pregnant passenger, Hung Choung-Hee, saying:

"Pregnant women are hardly offered seats when taking public transport. However, now people give me the seat after checking the pink light, which makes me feel much better. It has become more comfortable to use public transportation."

500 women in Busan, South Korea's second largest city, participated in trials of the new Bluetooth devices. Officials say the campaign has loftier goals than just helping pregnant ladies commute in comfort.

South Korean director general of Public Communications for Busan Metropolitan City, Kim Boem-Jin, saying:

"The city of Busan faces the challenges of a low birth rate and ageing population that many cities have. As a city operating under the motto of a 'smart city,' we have tried to help and support pregnant women using public transport by utilizing the Internet of Things (IoT) technology."

The city plans to gradually expand the campaign to other commuter train and bus lines.

Its designers think the scheme will be popular with both sexes. After all, it's sometimes hard to tell if a woman is pregnant …so this device could help avoid some really awkward moments.