For couples struggling to get pregnant, it can be upsetting to hear stories of a friend’s boundless fertility or to see a pregnant woman appearing around every second corner. It’s enough to make you think conception is easy for everyone except you.
That’s far from true: one in five couples experience some trouble in trying to conceive. There is increasing evidence, however, of the important role diet plays in fertility, and a growing recognition of the changes couples can make to optimise the chances of conceiving.
There is considerable evidence, for example, that body weight has a significant impact on subsequent fertility. Time to conception is twice as long for obese women (a body mass index of 30 or more) and four times as long for underweight women (a BMI less than 19) than for women of normal weight. It is well-known that the best way to achieve a healthier body weight is to embrace a healthy diet and lifestyle. But what’s less appreciated is that three simple diet and lifestyle improvements can also significantly improve the chances of conceiving: cutting out caffeine, alcohol and tobacco.
Some studies suggest that for people who consume more than two alcoholic drinks a day, the risk of infertility increases 60%. Likewise, consuming more than 250mg of caffeine – about two cups of coffee – a day may halve the chances of conception in a given time frame, according to a 2008 paper by the American Society for Reproductive Medicine. And, unsurprisingly, smoking also increases the risk of infertility.
Yet a recent study by dietitian Alice Redward – a member of Professor Wayne Cutfield’s team at the University of Auckland’s Liggins Institute – presented at the 2012 Fertility Society of Australia conference, had some startling findings. Among New Zealand women having in-vitro fertilisation (IVF) treatment at Fertility Associates clinics, some 51% were consuming alcohol and 87% were consuming caffeine one month before treatment. More worryingly, during IVF treatment around a third of the them were still consuming some alcohol.
Cutfield leads a clinical research group that looks at how environmental influences early in life can affect our growth, development and long-term health. He stresses that the mother’s diet and lifestyle are crucial both to the long-term health and the very existence of the child, as life begins when an egg developed inside the mother’s ovary is fertilised by sperm and both eggs and sperm take several months to mature. “Beyond fertility, arguably even more important is the question of what does it all mean for the lifelong health of that offspring,” Cutfield says.
Some women do get pregnant while eating an unhealthy diet, but ultimately their offspring will pay the price with an increased risk of long-term health problems such as insulin resistance, which creates a greater risk of diabetes, abdominal fat and hypertension.
Worse still, “the fetus can grow up to be an adult who transmits these health problems to their offspring. So it potentially has a long shadow.”
Alcohol should be avoided when trying to conceive, not least because there’s no safe limit of alcohol intake when you’re pregnant. Ideally caffeine intake should be reduced as much as possible, too, says Cutfield. In the Liggins Institute study, he says, “we found in that phase leading up to conception, women had not appreciably changed those lifestyle habits, and I think it’s part of that perception or illusion that pregnancy isn’t really happening yet. That’s not a unique finding to us”.
He says the women were given clear advice about avoiding alcohol and tobacco in the preconception phase, so it’s particularly surprising that this group, who were highly motivated to conceive, didn’t follow recommendations aimed at improving their fertility and potentially reducing the risk of harm to their unborn child.
The Liggins Institute study also found 17% of New Zealand women undergoing IVF weren’t consuming enough folic acid – the recommended dose is 800 micrograms a day for at least four weeks before conception and 12 weeks after conceiving to reduce the risk of neural-tube defects. Many of these women were taking advice from people such as staff in health-food shops, rather than from qualified healthcare practitioners. Consequently, some women were misinformed and believed their diet contained enough folic acid when in fact it didn’t, Cutfield says.
Although evidence linking folic acid supplementation to a reduced risk of neural- tube defects is clear-cut, it’s far more difficult for scientists to determine exactly what diet is optimal or perfect for fertility. “You’d need a cast of thousands – it would just be an impossibly large study to do,” says Cutfield, who believes the only feasible way of determining exactly which dietary components will optimise fertility and the health of the fetus would be for scientists to conduct an international multi-centred large study – which to date hasn’t been attempted.
Nevertheless, evidence suggests that just following the most basic guidelines for a healthy diet is likely to be beneficial for fertility. Yet the women’s diets in the Liggins Institute study were low in fibre and calcium; the amount of energy the women gained from carbohydrate-rich foods was below health recommendations; and their intake of sodium, total fat and saturated fat was higher than recommended.
“The whole concept that, in developed society, modern women follow recommendations for diet in pregnancy is not the case,” says Cutfield, who believes the most sensible approach for couples trying to conceive is to focus on following healthy eating recommendations before reaching for alternative health interventions for which there are no proven benefit and a considerable cost involved.
Up to a third of the women undergoing IVF were taking complementary medicines that are unproven in terms of benefits or efficacy, says Cutfield. “It isn’t very sensible to have a poor diet with high saturated fat, low fibre and low carbohydrate levels and then take fish oil and a whole bunch of other things like resveratrol.” Instead, Cutfield recommends those planning a pregnancy focus on a healthy diet and meeting dietary recommendations.
A healthy pre-conception diet should ideally be based on plenty of minimally processed whole foods, including wholegrains, high-fibre carbohydrate foods, lean meats, low-fat dairy products and at least two servings of fruit and three servings of vegetables a day.
OTHER THINGS THAT HELP
Washing your fruit and vegetables thoroughly is also a smart idea. A 2012 study, published in Environmental Health Perspectives, found that couples with higher levels of exposure to PCBs (polychlorinated biphenyls) and other environmental pollutants were likely to take longer to conceive. To minimise the amount of chemicals transferred to your meal, choose glass rather than plastic containers when microwaving food, and remove fat from animal meats, as many environmental pollutants accumulate in fatty tissue.
Removing fat from meat as well as skin from chicken is recommended, as is choosing lower-fat versions of dairy products, and avoiding takeaways, potato crisps, butter and pastry-based items; these all contain significant quantities of saturated fat.
Emerging evidence suggests saturated fats may reduce men’s fertility. A recent Danish study found men who ate the most saturated fat had 41% lower sperm counts. And researchers at Harvard University found higher intakes of full-fat dairy products were associated with abnormally shaped sperm. Although more research is needed to verify these findings, cutting down on saturated fat is still a good idea given its links to both heart disease and cancer.
Nonetheless, low-fat milk and dairy products should still be regularly included in the diet, as they provide a rich source of calcium. And equally important are protein-rich foods such as meat, chicken, fish and vegetarian alternatives, including legumes, tofu, nuts and seeds. As well as providing all-important protein, red meat is a rich source of iron, and oily fish is an excellent source of omega-3 fats.
THE IMPORTANCE OF PROTEIN
The contribution of protein to pre-conception diets was highlighted at the 2012 annual meeting of the American Society for Reproductive Medicine. Researchers reported that among 120 women having IVF, those eating a high-protein, low-carbohydrate diet were more likely to have their fertilised eggs successfully develop to the so-called blastocyst stage and to become pregnant.
In a smaller study involving just 12 women who had failed to fall pregnant after a single round of IVF, researchers advised the women to increase their protein intake and lower their carbohydrate intake. Blastocyst formation increased from 19% to 45% during their second round of IVF following their change in diet; similarly pregnancy rates increased from 17 to 83%.
These findings are considered preliminary and haven’t been published in a peer-reviewed journal, but they do raise interesting questions about whether the proportions of protein and carbohydrates in a diet influence the success of fertility treatments.
The overall picture that emerges is one of a healthy diet rich in fruits, vegetables, wholegrains, lean meats and fish, along with good vegetable-based oils – not dissimilar from a Mediterranean diet. A 2010 study in Fertility and Sterility found having a Mediterranean-style diet was associated with a 40% greater chance of pregnancy through IVF and intracytoplasmic sperm injection (ICSI). Likewise, a Spanish study, published in 2011 in Fertility and Sterility, also found an association between Mediterranean-style diets and less trouble getting pregnant.
Although these observational studies don’t prove this diet improved fertility, as more research is needed, there is nothing to lose and potentially a healthier cardiovascular system to gain by adopting a Mediterranean-style diet. So, try including lots of vegetables, fruit, wholegrains, nuts, seeds or legumes in every meal. And eat fish or seafood at least twice a week; poultry, eggs, yoghurt and cheese regularly; and meats and sweets slightly less often.
Although there is no miraculous dietary cure that will improve fertility, maintaining a healthy weight will certainly improve the chances of conception. Accumulating research certainly points also to a healthy diet playing an important role – although there is no indication yet that one type of diet is superior to another in terms of improving fertility. Instead, couples trying to conceive should focus on putting healthy eating recommendations into practice, says Cutfield. For example, it’s no use knowing you should eat five or more servings of fruit and vegetables a day but not actually doing it.