A growing number of British women are falling pregnant after a one-night stand

This summer's blockbuster romcom charts the story of a girl who has a baby after a one-night stand – a scenario all too familiar to a growing number of British women

If the countless media stories of infertility, IVF, ticking biological clocks and egg-stuffed freezers are anything to go by, you could be forgiven for thinking that natural, or speedy pregnancies are a thing of the past. But this summer's blockbuster romcom, Knocked Up, in which Seth Rogen (Ben Stone) finds his drunken, one-nightstand at his door declaring herself eight weeks pregnant, is a timely reminder that for some people, making babies can be scarily simple.

According to pregnancy advisory serviceMarie Stopes International (MSI), in January this year 13 per cent more women sought abortions than the previous year. Although there is always an increase in January, following all those brief drunken encounters of the festive season, this upturn was sharp enough to cause concern. "The rise was unprecedented," says Caroline Elliott of MSI, "We're observing it throughout the year to see if this is going to be an ongoing trend." One particular trend MSI have observed in the past decade is an increase in the number of single women seeking abortions.

This wasn't an option for Diana Gentile who fell unexpectedly pregnant even though she was on the pill. "It sounds crazy," she says, "but I literally rolled over knowing I was pregnant. It was like I felt a tiny shift in my body and I just absolutely knew." While it wasn't a one-night stand, Gentile had only known the father for four months. "He wasn't someone I'd ever consider to be a suitable life partner. Although we stayed together for much of the pregnancy, he has been completely absent since my daughter was four months old."

In the UK, 81 per cent people of a reproductive age use some form of contraception, and a quarter of all women aged 16 to 49 use an oral one. That's an awful lot of people not wanting to conceive. But a quick, highly unofficial straw poll among friends reveals more than half a dozen surprise pregnancies after short relationships or one night stands – even using a contraceptive. Somehow, it seems the figures aren't adding up.

Inevitably in these cases the father is often an absent one – the few that do stick around after a one-night stand tend to be in the minority. Boris Becker famously fathered a child in a quick-as-a-flash encounter in a restaurant broom cupboard, and received news of the impending baby via his office fax. As he mused later: "How do you build a relationship when you've hardly shared a word but suddenly share a child."

He's right, says Christine Northam from Relate, and fortunately these days there isn't so much pressure to force a romance out of an accidental pregnancy. "Shotgun weddings used to be common ," she says, " but nowadays there's no social stigma about being a single mother, so it doesn't happen. However, we always say it's still worth pursuing contact because the father is part of the child's life."

When 32-year-old Australian, Natascha Mirosch, returned home after a fun-filled holiday on a Greek island to find herself pregnant, she didn't have much choice in the matter as she and the father were separated by continents. "The first few weeks passed in a blur of vomiting, crying and booking and cancelling terminations," she says. "I would buy baby magazines in a fit of optimism, then feel it all crashing down as I contemplated my boozy Bridget-Jones lifestyle." A miscarriage scare at three months gave Mirosch the reality-check she needed, and six months later she gave birth to a son called Noah. It wasn't easy though – first she had to explain away the father to friends and family and then attend ante natal classes all alone. It was during yet another long, lonely night getting up for the baby that Mirosch resolved to write a book for others in a similar situation. Going It Alone, a single woman's guide to pregnancy, was such a success she now has her own website

Another person I spoke to who fell pregnant after a very short relationship, said there are other emotions to contend with. Although during the pregnancy the father stuck by her, when it came to the delivery, she asked him to sit outside the delivery suite – such was the embarrassment of having a virtual stranger, albeit the father – watch her give birth. Then here are all the other things childbirth brings with it – the leaky boobs, the saggy belly, not to mention the continual tiredness and irritability – so a well-established relationship, never mind a brand new one, is going to find that hard.

Single parenting also often goes hand in hand with financial difficulties, a problem which Gentile says she has grappled with. "Money is always tighter than I'd like," she says. "We do okay, but I feel as though I'm always trying to keep my head above water, and it keeps me up at night. It's definitely easier to work out support arrangements in a long-term relationship. Most men, even really good men, aren't particularly interested in raising a kid they made one drunken night with some random chick." *

Jennie Cairns, 40, and her son Oliver, eight months - 'I'd been on the pill for years'

One night I was really drunk and ended up back at my house with this guy from my local. I'd snogged him a few times but nothing serious. When my doctor said I might be pregnant, I thought it was crazy – I'd been on the pill for 20 years, and I'd never had a pregnancy scare. I even did two tests because I didn't believe it the first time.

It seemed like God's will, because I'd previously been in a six-year relationship and not got pregnant. I thought it would be selfish not to have the baby – I had a great job and great friends. I told the father by email, and said I hope you're sitting down for this. He called me straight away and was very cool about it, which was a shock, but nice. He did say if he was choosing a mum he would have picked me. I'm sure he was just being nice, but it made me feel good.

I made it clear I was having this baby with or without him, but I wanted financial support. We weren't about to walk down the aisle, but we did start seeing each other – to discuss things and sort out what we needed for the baby. He was available for the scans, but I chose to go it alone, as I knew in my heart I would be on my own eventually.

Oliver was born on 5 November, 2006. My best friend Helen was there for all 36 hours of hard labour. The father was asking Helen every five minutes if he could come in, but I just kept saying no until 10 minutes before I gave birth. Helen was so calming and kept me under control. She was amazing, I couldn't have done it without her.

Now there's no romantic relationship at all. His father supports Oliver financially: he agreed but I went through the CSA to settle it legally. Oliver looks like him, and is besotted with him.

My mum's been great, and there's a support network of young mums where I live. I work from home two days a week now, but I didn't take maternity leave. I haven't got the desire to go out as much any more, but I get out on one night at the weekend. I'm at the stage where I'd like to settle down – it's a bit lonely after the baby goes to bed. But it would have to be someone special, who'd know no one will ever take over as daddy.