But what exactly is hypnobirthing? And how, if at all, does it help women deal with the pain of giving birth and the anxiety that so often surrounds it?
The first thing to know, according to Katharine Graves, a leading practitioner and founder of KG Hypnobirthing, is that the term is wide and generic, and what it means in practice varies greatly. Broadly speaking, it involves breathing, visualisation and relaxation; but Graves says there's far more to it than this in her 12-hour course. Pregnant women will learn how to manage their fear around childbirth, which can in turn help bring about easier labour, she says.
"However much a woman is looking forward to having her baby, there will be a degree of maybe not fear but stress, or she might be suffering from extreme tocophobia [an intense fear of pregnancy and childbirth]. What fear does is change your hormonal response. When you're afraid, you produce adrenaline, and then...you're in the fight or flight response and it cuts out the hormone of oxytocin that makes labour work efficiently. So the work we do to reduce fear is massively important."
She also argues that the father has a very specific role to play in helping the mother during labour. Hypnobirthing can help him to feel confident and calm, as he'll know what is happening, be able to help his partner with relaxation techniques and know what questions to ask the midwife, in what Graves describes as a maternity system that can be "to a degree a conveyor belt" owing to scarce resources.
She likens the work couples do with her and at home before labour to the training an athlete puts in before a race. "The work is done in the days, weeks and months of training," she says.
To this end, couples are sent away from each session with exercises to practise together every day, which take between 10 and 15 minutes. They include two minutes of breathing, visualisations that the father can prompt the mother with while she's doing that, and an MP3 they can listen to when falling asleep at night.
"It sounds simple but it's very powerful," says Graves, who has been teaching hypnobirthing for 15 years. She charges £395 ($800 NZD) for a 12-hour group course and has 800 teachers on her list currently. Her organisation also goes into hospitals to train midwives in the technique.
"When we first started we had a stand at the London Baby Show," she says. "People would see it and give us a wide berth. Within about three years, people would see the same notice and say, 'oh yeah, I think my friend mentioned that, can you tell me some more?' Now every midwife in the country knows of it. It's growing all the time. I would say that we reach as an organisation probably up to 3,000 women a year."
Siobhan Miller, founder of The Positive Birth Company and author of the book Hypnobirthing: Practical Ways To Make Your Birth Better, believes the shift in attitudes has been helped by well-known women speaking out about the benefits of the practice. Angelina Jolie is reported to have used the tools, while fellow Hollywood actress Jessica Alba has spoken about her own experience of hypnobirthing.
"Celebrity endorsement has been huge," says Miller, who points to the growing number of YouTubers and other relatable social media stars also talking about practising hypnobirthing. She says Jessie Ware, the singer-songwriter, was among the 15,000 people a year to do her six-hour online course.
How would she describe hypnobirthing?
"[As] a programme of antenatal education. It seeks to educate women about how their body works on a muscular and hormonal level and [help them] understand how mind and body are connected. The science behind it is quite compelling and going hand in hand with that is trying to teach people to relax, because in our culture we're always on. So things like breathing techniques, they're for life, and essentially they help you to relax. Even when things perhaps don't go to plan...you have those tools to be able to stay calm and you can actually think more clearly."
Some of her hypnobirthing tutorials on YouTube have been watched more than 100,000 times, she says.
Many ordinary mothers speak extremely positively about the practice. "Hypnobirthing really helped me focus," says Jules, a 41-year-old mother-of-two who works in local government. "When the pain got too much, I suddenly remembered the breathing and focused on doing 20 breaths over and over. This took my mind away from the pain."
Tina, a 36-year-old lawyer and mother-of-one says: "It took away some of the intense fear of childbirth I had and it was also something we could focus on that we could both do together, before the baby came."
Others who have practised hypnobirthing sound a more equivocal note. "It did make me less scared about the idea of giving birth in the lead-up, but the focus on natural birth also makes you feel like such a failure if it doesn't end up going that way," says Cara, a 35-year-old mother-of-one who works in communications.
"It slams any sort of medical intervention and goes on about the baby coming when the baby is ready and how baby knows best. If I'd had no interventions, my daughter would have certainly died."
Graves stresses that at KG Hypnobirthing, they learn from the birth reports they receive from mothers who have done the course. "If [a mother] didn't quite get the birth she wanted, we look at it closely and think, 'is there anything we could have done that would have made a difference?' Sometimes it's not something we did or didn't do, but something someone else did that made her unsure of herself and made her agree to an intervention that might not have been necessary.
"We educate women...in order that they can make a choice to have the best birth for them. In our courses we always give a reason, we give logic, we give evidence."
She lists the six "c's" that parents say are important and which hypnobirthing can provide: choices, control, confidence, calm, communication, and - that holy grail of labour that every mother would certainly have if she could - a comfortable birth.
