MOST people take the ability to get pregnant for granted, yet around one in six UK couples struggle to conceive.

As a result, nearly 50,000 UK women a year try to have a baby through IVF, a fertility treatment which can of course bring great joy - but only after what can often be a nightmare process of hospital appointments, drugs, discomfort, waiting and possible disappointment.

Tru Spencer knows this process only too well, as she went through three cycles of IVF before the birth of her twins.

But the relief and joy that accompanied their arrival didn't diminish how hard the struggle to conceive them was, and now Spencer has written a book, Twin Stars and a Mother From Mars, about her IVF experience, both as a form of catharsis for herself, and also to help other couples thinking of embarking on the rocky IVF road.

"It was really tough," she says, "and I wrote my experiences down to get everything out of my head, like self-medication, and so other people going through IVF knew that what they were feeling was completely normal, and that they're not on their own."

In the book Spencer, now 43, explains how she and her partner James had tests in January 2005 after two years of unsuccessfully trying for a baby. The tests revealed James had a low sperm count and the couple would struggle to conceive. A consultant confirmed they needed fertility treatment - and Spencer admits she went home and cried.

"I knew that we were at the beginning of a hard road. The past few years of trying for a family would be nothing compared to what was to come," she says.

What was to come was seemingly incessant rounds of drugs through nasal sprays and injections to stimulate the production of eggs, numerous scans, sedations for egg recovery, and nervous waits to find out how many eggs were collected and whether they were healthy. Then the healthy eggs were inseminated with James's sperm in the laboratory to form embryos, and in each of the three cycles, healthy embryos were replaced into Spencer.

After the first IVF attempt, she showed faint signs of pregnancy but miscarried almost immediately.

"The feeling of the loss, and knowing that we'd have to go through IVF all over again, was really intense she remembers.

To make matters even worse, she then developed a condition linked to the overstimulation of her ovaries, and was hospitalised for a week.

The second cycle failed completely, but after Spencer changed clinics and had private IVF treatment she finally fell pregnant with twins.

Stanley and Mabel were born by Caesarian section in January 2007, and Spencer recalls: "We were handed both our babies and I was overcome by such indescribable raw emotion.

"All the past years of everything I'd experienced on the way to this moment came straight back.

"Finally, I was able to hold our twins."

She adds: "It's changed me, it really has. It puts everything in perspective."

She says she wasn't prepared for the intensity of the IVF process, and how it hit her emotionally.

"You think you'll be able to cope, but it makes you paranoid," she says.

"But it's absolutely more than worth it - being a parent is fab.

"If you're struggling to conceive and you can't envisage not having a family, then go for IVF if necessary. But be realistic about what you'll have to go through."

The couple had to pay for all three IVF cycles, as although the first two were done by the NHS, the hospital trust's IVF budget had run out.

Overall, the three cycles cost them around £15,000, and Spencer admits: "It made a huge hole in our finances, and we're still sorting that out six years after the twins were born."

Spencer is supporting Infertility Network UK's first Infertility Awareness Week (October 28 - November 3), and the charity's spokesperson Karen Veness, who had her first baby through IVF 15 years ago, says: "You become quite obsessive about it - it can take over your life."

She says two or three IVF cycles is normal for most people, and it's recommended that up to three cycles are provided for eligible couples on the NHS, although Veness says the reality is that it's "a postcode lottery" whether they get them or not.

In fact, Infertility Network UK estimates around 70% of healthcare providers don't offer three cycles.

"A lot of them still see IVF as a bit of a luxury, but I can so tell you it's not," she says.

"Money is an issue, but most people find it somehow."

Veness describes herself as "incredibly lucky" to have become pregnant through her first cycle of IVF, but says she's spoken to women who've been through as many as nine IVF attempts before conceiving.

She describes being told you'll struggle to get pregnant and may need fertility treatment as "a real blow", and says IVF is "truly horrible."

"It takes over your life - you just feel like you can't do something so fundamental," she says.

"You feel rubbish, sad and envious of women who were having babies easily.

"It rocks your world - but it really can be worth it."

:: Twin Stars & a Mother From Mars is published on October 14 by SilverWood Books, priced £9.99.

:: For more information and advice about infertility, visit the National Infertility Awareness Week website at www.niaw.org.uk, or ring the Infertility Network UK helpline on 01424 732361.

:: For additional information, visit the British Fertility Society website at www.britishfertilitysociety.org.uk, and people can also find out more at The Fertility Show at Olympia, London, from November 2-3 (www.fertilityshow.co.uk).