When Leigh Milner was expecting her first baby, she knew exactly how she wanted her labour to go. Her birth plan included an epidural for the pain and she was hoping, she says ruefully, for “all the drugs”. But that is not how things worked out. Milner, 33, a BBC presenter, ended up giving birth to Theo at Princess Alexandra hospital in Harlow last month with nothing but paracetamol for pain relief, in what she calls a positively “Victorian” experience.

Having been induced at 38 weeks due to pre-eclampsia, a potentially risky pregnancy complication that causes high blood pressure, labour progressed very fast and she soon realised she needed something to help her cope while she waited for her epidural. “The pain was just unbearable, my whole body was shaking – I didn’t know where I was, I was kind of slipping in and out of consciousness,” she says.

At this point, many women would take a gulp of gas and air, the bedside mix of oxygen and nitrous oxide familiar to mothers as the commonest form of pain relief in labour. But at the Princess Alexandra, along with a handful of other hospitals across south-east England, supplies were temporarily suspended when Milner gave birth in February after the hospital found excessive levels of nitrous oxide (which can pose a longterm health risk to midwives) in the air on the ward.

“I kept begging over and over again – ‘I need something for pain relief’ – and the only thing they could give me was paracetamol because they didn’t have gas and air. I was quite frightened, I didn’t know what else to do,” says Milner. It was only when she reached the labour ward that staff told her there wasn’t time for an epidural. She delivered Theo while being prepped for an emergency caesarean and was left “writhing in pain” for hours afterwards, while her husband, Chris Berrow, looked after the baby. “It seemed like it would never end – it was a mess from start to finish. I understand they have to keep the staff safe, but they also need to support women giving birth,” says Milner, who is keen to talk openly about the experience because of what she sees as a broader expectation that women in childbirth should just grit their teeth and bear it. “There’s a kind of ‘get on with it’ attitude. And yes, I have a lovely healthy baby boy and I would do it all again for him, don’t get me wrong. But I don’t think we can just keep saying to mothers: ‘At least you have a healthy baby, move on, it’s fine.’ Birth is painful, but it shouldn’t be traumatic.”

Seventy-six per cent of women who gave birth in England last year used gas and air at some point in labour, according to the Care Quality Commission (CQC) watchdog. It doesn’t so much remove the pain as make it more bearable. But it is popular because women can help themselves as necessary, it works quickly and it doesn’t slow down contractions (which stronger opioid painkillers such as pethidine can). While some women use it only as a stepping stone to something stronger, others build their hopes of a “natural” birth with minimal intervention on it. But as Milner found, concerns over air quality, particularly in older maternity units, mean that it cannot currently be taken for granted in some parts of England.

Research shows that while inhaling gas and air (known as Entonox) in labour is perfectly safe for mothers and babies, long-term cumulative exposure – for example in midwives working day after day on badly ventilated wards, with gas accumulating in the atmosphere – may carry health risks. Over time it can affect the ability to absorb vitamin B12, damaging nerves and potentially causing anaemia. Some studies have associated occupational exposure with fertility problems and risk of miscarriage, although research is not conclusive.

Last November, the William Harvey hospital in Ashford, Kent, restricted access to gas and air after detecting high levels of nitrous oxide on the unit (it’s since been restored). Weeks later, Basildon University hospital in Essex temporarily suspended gas and air, saying previous tests had shown “an issue” with levels of nitrous oxide on the maternity unit. Some staff in the unit are reportedly considering legal action against the Mid and South Essex NHS foundation trust that runs the hospital, and the Health and Safety Executive is investigating.

Ipswich hospital also suspended gas and air use last December, but reintroduced it after installing new ventilation, and in late February, North West Anglia NHS foundation trust temporarily suspended gas and air at maternity units in Peterborough and Huntingdon following air-quality tests. Meanwhile, Watford general hospital avoided a break in Entonox provision after recording high levels in its maternity unit by installing machines to extract the gas. (Princess Alexandra hospital, where Milner gave birth, says it now has three temporary gas-and-air units available, with permanent ones coming soon.)

Pain relief in labour is an emotive subject, laced with guilt and arguments about whether suffering is an essentially “natural” part of childbirth or something nobody would be expected to endure in other fields of medicine. Even before the current problems with gas and air, some mothers struggled to have the birth they wanted. In 2019, the CQC found more than a third of women switched from their planned form of pain relief in labour, mostly for medical reasons, but in 3% of cases because there was no anaesthetist available (only anaesthetists can give epidurals) and in 19% of cases because there was no time for what they had wanted.

For those whose labours come on suddenly, gas and air may be the only option. “It takes the edge off and makes you feel calmer,” says Kathie, a mother of two daughters from Suffolk, whose labours both took two and a half hours from start to finish, with no time for an epidural. “It also makes you feel less anxious because it gives you something to do – even the act of having the gas mask and breathing in gives you something else to concentrate on.” It helped her to feel less out of control, she says, when things were moving frighteningly fast. But if gas and air can be a godsend for mothers, it carries potential hidden dangers for those looking after them.

Leah Hazard is an NHS midwife in Scotland, an activist and the author of Womb: The Inside Story. She has been approached by several midwives in recent weeks about the impact high Entonox levels at work may have had on them, she says: “There’s a genuine feeling of frustration, anger and fear because some of the midwives have had real issues with their health and fertility – and, in some cases, B12 deficiency. They are looking back and feeling really quite angry about it. I’ve also spoken to midwives who haven’t tried to start a family yet but have been working in labour wards and are worried some damage may have been done.”

While hospitals have been criticised for suddenly suspending services, Hazard points out that it is unreasonable to expect midwives to risk their own health. “You would never say: ‘Why don’t builders just keep working on that building with asbestos for a few weeks longer?’ It’s primarily a service by women for women, and [midwifery] was always a role deemed to be warm and fuzzy, and docile. There’s an assumption that we should just put up and shut up.”

Since the potential risks from Entonox – also used in dental surgeries and, more rarely, operating theatres – have been known for decades, she argues, hospitals should have prioritised ventilation before now. The Health and Safety Executive investigation into what happened in Basildon may shed some light on why problems are only now emerging in a number of hospitals.

The Royal College of Midwives has also argued that the current crisis reflects a lack of what Dr Suzanne Tyler, executive director for services to members, called “proper investment” in maternity services, which have long suffered from chronic understaffing and creaking old buildings. “This issue has arisen because of poor ventilation in delivery suites and labour wards – but this is just the tip of the iceberg. We know of crumbling walls, ceilings being held up by props and even sewage flowing on to wards. During Covid-19, a lack of decent ventilation, and appointments taking place in tiny rooms, meant that birth partners were unable to attend scans.”

For many midwives, Hazard says, the fact that the risk from Entonox is seemingly highest in older hospitals with poor ventilation revives unhappy memories of the pandemic. “We were well aware then that we were often working in badly ventilated rooms, not shiny new buildings. Many of us caught Covid and have been very ill,” she says. For many midwives, these new worries about safety are “the last straw”. But staff are also, she says, concerned about the impact of painkilling methods being withdrawn on the women they look after.

In theory, there are plenty of alternatives, from “natural” options such as hypnosis and water births to stronger opioids such as pethidine. But Hazard says there is no exact equivalent to gas and air. “They all have their own specific profiles in terms of risks and benefits – it’s not like you can say, ‘Really sorry, we don’t have any gas and air, but why don’t you have some morphine?’ That’s a totally different step up the ladder. Or: ‘Sorry, why don’t you have the birthing pool?’ Well, not everybody wants to give birth in water.”

The National Childbirth Trust (NCT), which has been fielding calls from worried pregnant women, is advising those in affected areas to ask their midwives about other methods, or see if they can switch to another hospital. For those seeking epidurals, who might normally use gas and air while waiting for the anaesthetist to get to them, the NCT’s practice manager, Val Willcox, says wards should always have enough anaesthetic cover to meet epidural demand, but women “might want to think about other strategies for coping with contractions” if there is a wait at busy times. Non-medical interventions – deep breathing, massage and hypnosis – are the next most common form of pain relief after gas and air, followed by Tens machines, which use electrical pulses to relieve pain.

It is crucial to resolve the uncertainty on some maternity wards because having some sense of choice and control during labour is key to wellbeing both in childbirth and early motherhood, says Francesca Treadaway of the campaigning charity Birthrights. “Giving birth is a life-changing event – it’s seismic – and birth is your introduction to parenthood. How the birth goes affects how you feel postnatally, too,” she points out. “You do have rights over your treatment, whether that’s giving birth or having another kind of operation. When choice is taken away from you, that’s traumatic.”

Birthrights has taken several calls in recent weeks about gas and air, she says – some women only realised it had been withdrawn from their local hospital after reading about it on social media. Treadaway is particularly concerned about the impact on pregnant women who had their first babies during the pandemic, on labour wards operating under severe covid restrictions, and who may be carrying difficult memories from that time into a second pregnancy. “At best, you are going in with a degree of apprehension.”

Six weeks on from Theo’s birth, Milner is recovering well and clearly besotted with her son. But her distressing experience on the labour ward did, she says, colour their first days together. She is keen to take up the hospital’s offer of a “birth reflections” session to go over and process her experience with a midwife. “I do feel like it kind of robbed me of those nice feelings that you’re supposed to feel, because I’d look at him and feel so happy and so grateful that he’s here, but then I’d start crying because the moment he came into the world was not a happy time. I didn’t have that euphoria, when people say: ‘I looked at him and fell in love.’ I looked at him and felt relief that we both survived.”

• This article was amended on 20 March 2023. An earlier version said that gas and air was restored to some delivery rooms at the William Harvey hospital; it was restored to all delivery rooms.

• Peer supporters at the Birth Trauma Association can be contacted at support@birthtraumaassociation.org.uk or by calling the helpline: 0203 621 6338.

• Do you have an opinion on the issues raised in this article? If you would like to submit a response of up to 300 words by email to be considered for publication in our letters section, please click here.