Most women who have ever had to express breast milk will recognise the facial expressions of the comedian Amy Schumer in the pictures she has put up on her Instagram account in the past few weeks. There she is, hooked up to her double breast pump, looking tired and a bit bored, and at the same time grateful to be sitting down. As you may expect from Schumer’s work, it’s relatable – more so than the proliferation of more glamorous breast pump selfies from celebrities such as Chrissy Teigen, Pink and Kate Upton.

At least they are all making milk expressing more mainstream, a momentum that has been building for a while. The actor Rachel McAdams was photographed for a magazine last year accessorising her double breast pump with diamonds and a Versace jacket. The TV series The Good Fight recently showed one of the lawyers expressing in her office and, last September, the model Valeria Garcia walked the catwalk at London fashion week “wearing” a breast pump. Amid the random, but pricey, selection of wares that made up the goodie bags for the nominees at the Oscars earlier this year was a breast pump – perhaps the surest sign yet that expressing milk is coming out of the closet and becoming more visible.

Chrissy Tiegen expressing in the car, with her husband John Legend. Photograph: Instagram/johnlegend

In February, the Labour leader Jeremy Corbyn retweeted a news story about breastfeeding working mothers being forced to express in the toilets, adding “so much more needs to be done to make our workplaces welcoming for new mums”. Which isn’t an unusual or controversial opinion, but the accompanying large photograph of a woman using a double breast pump was an uncommon and arresting sight.

Last year, an image went viral of the athlete Sophie Power feeding her three-month-old son on one breast while pumping milk from the other at a rest stop during the 105-mile Ultra-Trail du Mont Blanc race. This year, another ultrarunner, Jasmin Paris, stopped along the 268-mile Montane Spine race – which she won, with hours to spare – to express milk for her 14-month-old daughter.

I have not expressed breast milk while performing such heroics, although I did once do it in the stinky toilets on a moving Southeastern train. Returning to work five months after the birth of my second baby – and having chosen, and been able, to breastfeed – I am having to reacquaint myself with my breast pump. First time around, I had to express to increase my nonexistent milk supply, and my stubborn wish to breastfeed meant I was trapped in a bovine and mostly miserable cycle of feeding, then pumping with the double-attachment hospital-grade machine I had hired, then feeding again.

Once back at work, a less alarming electric pump allowed me to keep breastfeeding (I had soon ditched the manual pump I had tried). My relationship with my Medela pump varies between gratitude and grudge. It has allowed me to continue breastfeeding – and allow other people to take on feeding duties and prevent infections such as mastitis – but the constant sterilising, assembling, transporting, labelling, freezing and defrosting is a hassle.

I am lucky in that I work mainly from home, but I have expressed while commuting, in department stores and pub toilets, while driving (not advised) and, once, sobbing in the ladies’ toilets while on a press junket – with painful, solid boobs and a pump that had run out of batteries – hand expressing into the toilet bowl. And yes, I realise how filthy that sounds. Who knows what the other journalists thought I had been doing when I crept into a group interview, late and stained. That was only four years ago but, as a measure of how much more visible milk-expressing has become, this time around I would ask for a proper place and time to do it.

Using Medela’s breast pump requires constant sterilising, assembling, labelling and freezing Photograph: PR

Breast-pump companies are reporting rises in sales – Medela, the market leader, says sales have grown at roughly 10% a year for the past five years – and tech businesses are taking notice. The first Make the Breast Pump Not Suck hackathon was held by the Massachusetts Institute of Technology in 2014 to improve a machine that had barely changed in several decades; the project, which aims to support breastfeeding innovation, is still going.

The Elvie pump (from the makers of the Elvie kegel trainer) – the one included in the Oscars swag bag – was launched in September last year and the company has raised millions in investment. It already has a strong social media presence, where women share pictures of themselves pumping. The pump is designed to be worn inside your bra, with no wires or tubes and can be controlled by an app on your phone that tells you how you are doing. The maker claims you can pump “at home, at work or on the go”, and even suggests you can “lead the meeting”. Would you want to lead a meeting while a machine drains your breast? I suppose some women might (or might have to). But one of the benefits I have found about breastfeeding, and expressing, is that you get to sit down a lot.

I tried the Elvie pump at home, enjoying the novelty of being able to move around and get on with important tasks such as foraging for snacks. It feels modern – I charged it through the USB port on my laptop – but is expensive at £249 for a single pump. It is not as discreet as Elvie claims. Although it is very quiet, when popped inside your bra it creates the appearance of a noticeably giant breast. I synced it to the free app, which means you can control the pump using your phone, and monitored the use in real time: 12 minutes on one side should have produced 30ml of milk. But it turned out to be wrong – it is only supposed to be an estimate, but when decanted into a measuring jug, there was nearly twice that amount (when you are expressing, you become obsessed with every drop because getting it out is such a bore). I regularly started using the pump on train journeys, and once in a restaurant, although I soon gave up on the app. But if you are the sort of Oscar nominee who enjoys being untethered and monitoring bodily functions, I can see its appeal.

The Elvie breast pump, showing front and back views

And if you are the sort of employer who doesn’t feel like giving your new-mother employees the time and space to express milk, I can also see its appeal. I doubt this was the maker’s intention, but it is easy to see how milk-expressing wearables might become an unwelcome solution to the problem of pumping while working.

If milk-expressing – that reality for many working women who breastfeed – is becoming more visible, legislation is still to catch up. “The law as it stands is inadequate with respect to what employers are required to do to support breastfeeding mothers returning to work, including those who wish to express at work,” says Paula Chan, a specialist employment lawyer at Slater and Gordon. In the UK, there are no rights to paid breaks or even “a basic legal requirement to provide facilities to enable mothers to express milk”, which should include a private room and somewhere to store milk.

“In terms of what employers are required to do, there is a duty to provide a place for breastfeeding mothers to rest, and to carry out a risk assessment of issues, such as working conditions, or risks to the health and safety of the mother or her baby,” says Chan. Employers are also legally required to consider flexible working requests, which a mother might make to accommodate breastfeeding.

According to the 2010 Infant Feeding Survey, almost a third of working mothers had returned to work when their babies were between eight and 10 months old – when they are still very much reliant on milk. Just one in five working mothers – and nearly a quarter in Scotland – said that they were given facilities to feed or express at work.

Ros Bragg, director of Maternity Action, which campaigns for the rights of pregnant women and mothers, says there is concern about the UK’s comparatively low rates of breastfeeding, but this hasn’t translated into any changes in the law that would help breastfeeding mothers returning to work. “It wasn’t addressed in the Taylor review into modern working practices [an independent report submitted to the government in 2017], it’s not part of the recent NHS long-term plan and is simply not visible on the government’s policy agenda,” she says. “We’re often frustrated that the needs of pregnant women and new mothers are not treated as a priority in decision-making by government.”

The model Valeria Garcia appearing on the catwalk wearing an Elvie breast pump at London fashion week in 2018. Photograph: Eamonn M McCormack/Getty Images for Elvie

The UK, unlike many other European countries, she says, is unusual in not having a statutory right to breastfeeding or expressing breaks. “As a result, women who would like to express milk on their return to work are very much reliant on their employer’s good intentions.”

A study this year by Slater and Gordon found that one in three breastfeeding mothers had been forced to use a toilet to express milk. Of the 2,000 working mothers surveyed who had had a baby in the past five years, 18% had had to use a staff room for expressing, 14% had used their car and 11% had had to do it at their desk. Most women – 70% – said their employer didn’t raise the issue before they returned to work, but 29% of women said they had felt too embarrassed to talk about it. As a result, they reported, women experienced leaks, which were embarrassing, and also career-hindering issues such as missing out on important meetings.

When Caroline went back to work as a supply teacher after her first child was born, she would ask where she could express but, going into different schools every day meant people often forgot about her request. On her first day back, she expressed milk in the cupboard in her classroom, sitting on the floor. Now back at work after her second child turned eight months, Caroline is expressing again. This time, she is working in a school where the teachers are with the children all day, so it’s a case of finding a quiet 10 minutes to go and express when she can. Some days she doesn’t get the chance, which can be uncomfortable. “Apart from the toilets, there aren’t any rooms I can lock,” she says. Instead, she uses an empty room and puts a chair in front of the door to stop children walking in. Has she felt embarrassed about asking where she can express? “Yeah, it feels like an odd thing to do – I think particularly at a school with children around, where I’m sitting in a room with my boobs out.”

For many women, expressing is not simply a case of strapping on a pump and getting on with it. Stress will affect the letdown (the reflex that prompts milk to flow) and the amount of milk you can get, says Helen Gray, from the breastfeeding organisation Lactation Consultants of Great Britain. “Feeling private and safe has an effect on your hormone levels. Having a comfortable room and a locked door can make a big difference to mothers who are feeling nervous about having to do this in the workplace.” Ideally, working mothers who are breastfeeding shouldn’t be feeling nervous in the first place. If taboos around breastfeeding have largely been shattered, expressing is still relatively hidden – celebrity selfies and photographs of ultrarunners may help to normalise it, one fluid ounce at a time.