Stephen Mangan: Motherhood is no laughing matter "My job is to portray that huge range of emotions that rush through you while you're watching someone give birth or you're giving birth," he says. Not just the elation and the excitement, but the boredom, misery and terror. "The fact that it's a man giving birth is interesting," he continues. When I first heard the idea, I thought: 'There had better be a good reason for this. It sounds like it could be gimmicky, but once you read the play you realise that swapping the genders throws a new light on the subject. You take it for granted, for example, that women are going to be physically humiliated and compromised, while the men are left standing helpless - or worse, clueless - on the sidelines. Although he conducted some background research on the topic in the expected quarters - visiting National Childbirth Trust classes, talking to pregnant women and midwives - inevitably he's drawing as best he can, with added imaginative input, on recent personal experience. Digging into all that is almost more daunting than any of the physical carry-on, he says. In a way, having a catheter put in you, or your anus interfered with, is easier than opening up your fears and worries. It's the soul-baring that's the hardest thing. Being a man in a woman's situation - and not just any situation, but one of the most emotionally turbulent situations possible - and then showing the audience how that's affecting you is tough. Even though he and the cast, which includes Lisa Dillon as his high-powered wife, have had only a few try-outs ahead of the opening night tonight, he's already experienced the urge to turn upstage, away from the audience. It's so deep and personal. It's a far cry from the emotionally disconnected world of Green Wing, the hallucinogenic Channel 4 comedy in which he played bumptious anaesthetist Guy Secretan, one of a certifiable cluster of medics for whom the hospital patients were as good as invisible. "In a way, you could say we're exploring the powerless in this piece rather than the powerful - and negligent - in Green Wing," he reflects, pointing out that Penhall intends the play to be, in part, a critique of the NHS. I think he feels that the system abuses the fact that women forget what it's like and that you often don't want to talk about the experience or go back and complain because you've got a new baby to deal with. It's as a hypothetical slightly futuristic "what if?," though, that the show will surely stir the most debate. Would Mangan himself go through the ordeal of birth, were such Frankenscience possible? Does he approve in principle? He pauses. I think it would probably be an incredibly valuable thing for a couple to have the ability to do this. We are already living in a world where people are getting other women to have the baby for them - that's no less weird. I think the uptake would be enormous once people had got past the novelty. Would I be prepared to do it? That's another matter. But yes, I suppose so, though I'm spared the decision. At the moment, the idea exists for many people on the level of a joke, even a sick one. If Mangan's over-riding ambition in the coming years is to tackle serious roles and avoid repeating himself - "You can get put in a box very easily" - his immediate goal is to stop audiences having too much of a good time at his character's expense here. "There are a lot of lines that are getting laughs in the second half of the play," he says, rather peeved, "and I'm trying as hard as I can to deliver them in ways that they won't, because the audience are laughing at a man in pain." He sounds almost maternally protective of this one-in-a-million paterfamilias. Yes, he feels for the poor guy. "In a way," he confesses, mock‑solemnly, "I'm actually quite upset that there are any jokes in the play at all." Birthday" is at the Royal Court (020 7565 5000) until Aug 4