After new research suggests sunlight boosts fertility in both men and women, experts discuss the natural alternatives to IVF for couples struggling to conceive - including taking sunshine holidays.
By Lisa Salmon.
For couples who are struggling to start a family, the answer could be simple: take a break in the sun.
The latest research shows that sunlight boosts fertility in both men and women by increasing their levels of vitamin D, which helps to balance sex hormones in women and improves men's sperm count.
Many previous studies have also found major benefits from using natural ways to boost fertility, including research from Harvard Medical School which showed that women with ovulation problems who ate healthily and exercised were 80% less likely to experience infertility.
Yet despite the many ways to naturally and cheaply improve fertility, more and more couples are trying the often difficult and expensive assisted conception route.
The latest figures from the Human Fertilisation and Embryology Authority (HFEA) show that in 2010 there were 57,652 assisted conception treatments (IVF or similar) in the UK, an increase of 5.9% on the previous year.
But as the overall pregnancy rates for such treatments stand at just 33.4%, it seems that changes to diet and lifestyle and a relaxing, sunny holiday may give the UK's one in seven infertile couples the best, and certainly the most enjoyable, chance of conceiving.
The most recent review into the fertility-boosting effects of vitamin D, led by Dr Elisabeth Lerchbaum at the Medical University of Graz in Austria, found that in females, sex hormones progesterone and oestrogen were increased by up to 21% and for men, testosterone levels were higher, improving their libido and semen quality.
"As low vitamin D levels are associated with decreased fertility in women as well as in men, increasing levels might improve fertility," says Dr Lerchbaum.
"People could either spend more time outside in the sun - but this might be dangerous because of increased risk for skin cancer - or they could take vitamin D supplements, which is a safe and cheap way to increase vitamin D levels.
"In some couples, such supplementation might be a sufficient treatment to fulfil the desire to have children."
But if extra sunlight or vitamin D pills don't do the trick, there are plenty of other ways to boost fertility, says Diane Arnold, who runs the telephone advice line at Infertility Network UK.
Diet is a major factor and Arnold suggests that couples trying for a baby should eat plenty of fresh fruit, vegetables and wholegrains which help boost the immune system.
"If the immune system's OK you've got a better chance of embryos implanting naturally," she explains.
She also suggests that both men and women should cut down on caffeinated drinks and consume more water and fruit juice, to keep the system flushed out and introduce more vitamins and minerals.
The 2007 Harvard study found that women with ovulation problems who ate less trans-fat and sugar from carbohydrates, consumed more protein from vegetables than from meat, ate more fibre and iron, took more multivitamins, and, surprisingly, consumed more high-fat dairy products and less low-fat dairy products, reduced their risk of infertility by 80% compared to women who didn't try any of the measures.
A lower body mass index (BMI) and exercising for longer periods each day was also associated with the reduced risk, and certainly consultant gynaecologist Dr Jonathan Lord, of the Royal Cornwall Hospital, suggests that while a healthy diet is important, physical activity is even more vital.
"We feel exercise is the crucial thing," he says.
"All the evidence shows that people who take regular, proper exercise have many health benefits, and we suspect fertility is one of them and that's more important than diet itself."
It's not specifically known why exercise is so important for fertility, although it seems to be key to reducing insulin resistance, which creates many fertility problems including polycystic ovary syndrome.
It's also critical that both men and women stop smoking, as it measurably reduces fertility and has negative consequences for any pregnancy, says Dr Lord.
Again, while it's not known exactly how smoking affects fertility, it may be the toxic effect of the smoke, or the impact on embryo implantation or, says Dr Lord, "almost certainly a combination of both".
The official advice, he explains, is also to stop drinking alcohol before conception, but he says: "We don't advise that for our patients - leading a healthy social life is probably more important than trying to do something unrealistic, and drinking in moderation seems to make sense.
"Our advice is to lead as healthy a lifestyle as possible but also as normal a life as possible.
"Being healthy clearly makes sense, as people's systems can then provide all the resources fertility needs. But going too far the other way probably leads to stress and anxiety - there's a law of diminishing returns."
While Arnold says avoiding stress can make a big difference to reproductive health, Dr Lord points out that although stress doesn't help fertility, it's "very much not a barrier" unless it's severe.
He emphasises that it's vital for men who want to father a child to follow healthy lifestyle measures too, pointing out that much fertility advice is focused on women, which is unfair.
"All the evidence is that these measures affect men just as much as women and most of these things can only be a joint effort - one person stopping smoking just wouldn't work."
Dr Lord points out that if couples are on the threshold of infertility, adopting a healthy lifestyle could tip them into being fertile - particularly if they're among the 30% of couples whose infertility is classed as 'unexplained'.
"I think if those couples adopt a healthy lifestyle, they're significantly more likely to have success," he says.
"Ultimately, fertility is a chance event, and the more you can do to put the odds in your favour, the more likely you are to be successful.
"None of these things are an absolute, but they will just shift the goalposts slightly."
He stresses that if a woman isn't producing eggs or has blocked fallopian tubes, or a man isn't producing sperm, the measures won't work. But such cases are rare.
"It's usually a combination of minor factors that are ganging up against a couple, and the things they can alter may well balance it out."
He points out that adopting the healthy fertility measures will, of course, benefit individuals anyway, regardless of the fertility outcome. But if the measures do succeed, a successful, healthy pregnancy is much more likely.
He adds: "It's notoriously difficult to get people to change their lifestyle, but we find our fertility patients are incredibly motivated and they tend to be able to do it.
"What really strikes me is not just that quite a few of them have success, but they nearly always come back and say they feel so much healthier and better about themselves.
"It's not just fertility, it's better all round."
:: For advice on infertility, visit www.infertilitynetworkuk.com or contact the Infertility Network UK advice line on 0800 008 7464