If a pregnant woman wants a shorter labour, preparing the father-to-be for the process is key.
That's the claim of the UK's first male antenatal educator Dean Beaumont, who says labour is likely to be quicker if an expectant dad is fully informed about the birth process and his partner's wishes, and supports her to the best of his ability.
In his new book The Expectant Dad's Handbook, Beaumont stresses that during childbirth, the father-to-be has two main roles - to be his partner's protector and advocate.
If he fulfils these roles, he can help shorten labour, Beaumont promises.
This, he says, is because protecting the woman and making sure her wishes are heard is linked to less production of the hormone adrenalin, which he describes as the "enemy of labour".
Adrenalin kicks in when the mother is frightened, he says, and can slow the birthing process because it neutralises the hormone oxytocin, which relaxes the woman and helps labour.
"I call adrenalin the grizzly bear, and I teach dads what could possibly lead to its production, and stress that their role is to protect the environment around mum and make sure she doesn't worry about anything," says Beaumont.
"A prepared dad has it within his power to make labour shorter and more comfortable, but on the flip-side, an ill-prepared dad can actually make labour longer, with worse outcomes."
Such crucial advice is just one of many dad-centred nuggets in the handbook, which father-of-two Beaumont hopes will provide all the practical and emotional information expectant fathers and new dads need to be the best father possible.
"There are books for fathers but they seem to feel there has to be an over-the-top humour element," he says.
"What I always felt was missing was a down-to-earth book about a dad's role during pregnancy, labour and baby's early days, from a male perspective."
He says the guide is very factual and not over-medicalised, pointing out: "Dads don't need to know how a pelvis works. What they need to know is what their role is and how to best support their wife or partner and be the best dad they can."
Beaumont, whose wife Steph is expecting their third child this summer, wrote the book after founding DaddyNatal, a programme which gives men information and support to prepare them for their role in childbirth and as a father.
He created the programme after his first child, Oren, was born and he couldn't shake the guilty feeling that he hadn't done enough to help his wife during the birth.
The former building plastics company manager went on to complete a childbirth education diploma before founding DaddyNatal.
At DaddyNatal classes and in the book, Beaumont talks about neonatal baby development and new baby care from a dad's perspective, as well as outlining how men can best support mums through pregnancy and labour.
In addition to being the mother's protector, the father-to-be should also be her advocate, making sure her wishes are heard and understood by others, stresses Beaumont.
This means a couple should have already discussed birth preferences and decided what birth choices they both think they'll be happy with.
But Beaumont stresses that if a couple can't agree, the woman's wishes come first.
He says expectant mothers might ask dads-to-be to read one of their pregnancy or parenting books, but many only flick through because most of what's in there isn't relevant to dads.
"Sometimes mums and dads aren't on the same wavelength, and don't fully understand what the other's going through," he says.
"If men see a loved one in pain, our natural reaction is to want to fix it. But during birth, this could be detrimental if you don't understand what's going on.
"Dads can try to guess what's happening, and they may end up asking for an intervention that mum doesn't want - they might almost push pain relief, for example, on the mum."
To the undoubted satisfaction of many mothers, he admits: "As a man, I don't claim for one second to actually comprehend what a woman's going through, even with my background.
"So what chance has a poor dad going through it with his partner for the first time got?
"I want to give him roles to stop him trying to fix things, and that's where being a protector and advocate comes in."
Beaumont stresses he's not trying to get dads to take control of birth, but rather to take control of themselves and support mums.
After baby's born, he points out that the father's understanding and knowledge about issues such as breastfeeding and postnatal depression is crucial.
"Dads want to be involved, but it's not as natural for us," he says.
"We do make mistakes with our newborn babies, and because mum is trying very hard as well, she wants dad to do it her way instead of accepting that both can do it their own way.
"Part of our male psyche is that if we're criticised we tend to withdraw, and give up because we feel like we can't do it right.
"We do things differently, and if that was accepted it would make life a lot easier."
:: The Expectant Dad's Handbook is published by Vermilion, priced £10.99. Available now.