It is a truth universally acknowledged that you don't ask a woman if she's pregnant. Ever. But it's also considered good manners to offer a pregnant woman a seat on public transport, so how can these two pieces of modern sensibility exist in concert with one another?
You should give up your seat to a pregnant woman but you can't make any assumptions or ask if she's pregnant. It's a conundrum.
Standing up for an extended period of time can be uncomfortable – and sometimes downright dangerous – for pregnant women. Body parts can ache. Balance can be lost. Blood pressure can drop.
As someone who has fainted on a bus while pregnant – not once, but twice – I gave up suffering early on and became comfortable loudly asking people to give me their seats. But surely there has to be an easier way.
New York City is the latest place to offer a solution: the Metropolitan Transportation Authority is offering "Baby on Board" badges to pregnant women, in the hope that people will see the badges and offer their seat.
The badges are free, although they take three weeks to be sent out from the time they're ordered, so you'd need to plan ahead.
It could be just what the city needs - New York was, of course, where one woman travelled daily on the subway throughout almost two entire pregnancies before being offered a seat. When one man finally noticed she was standing while eight months pregnant and gave her his seat, she awarded him the 'Decent Dude' trophy she'd had made for exactly that situation.
When it comes to badges, however, New York's program isn't the first: London has run a similar program on its Underground service since 2005 for pregnant women and parents with strollers. It has proven to be immensely popular.
South Korean transport authorities have come up with a much more high-tech – and perhaps more dignified – way for expectant mothers to be offered a seat. The Pink Light program involves pregnant women carrying sensors that activate pink lights next to priority seats on trains.
The sensors, which operate on Bluetooth technology, have six months of battery life and need to be carried outside a woman's handbag for the signal to be strong enough. When a woman carrying a sensor boards a train the pink light near the priority seat lights up, alerting anyone sitting there and reminding them to offer their seat.
In the meantime, Australia has no programs to encourage people to offer their seats to pregnant women. But as public transport becomes busier and more crowded – especially in our capital cities during peak hour, perhaps it's time we did.