What is the best pre-pregnancy diet to optimise fertility?

This is a guest post by Registered Dietitian, Claire Pettit of CP Nutrition

For anyone trying to have a baby, I’m sure you will have seen the wealth of suggestions and advice available on the internet about how to improve your chances of getting pregnant.

Although we all want to do the best we can to improve the chance of conceiving, some of these suggestions are idealistic and misleading and not supported by scientific evidence. 

And for some, what should be a beautiful phase of life when trying to have a baby, turns out to be a stressful and guilt-ridden time, which doesn’t go to plan.

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How common is infertility?

Around 1 in 7 couples struggle with infertility (being unable to conceive within 1 year of trying) in the UK [1], so despite it still being somewhat of a taboo subject of discussion, it is not an uncommon problem.

Although this article concentrates mainly on female fertility, it is important to realise that fertility issues can affect both females and males with males being responsible for 20-30% of infertility cases [2] and so if you are trying to conceive, then addressing both partners risk factors is essential. After all, it takes two to tango!

What impacts female fertility?

Although nutrition is an important part of preparing your body for a healthy pregnancy, we must not forget that there are many other factors at play which may have an impact. This includes:

AGE: Women are born with all their eggs and as we age the quantity and quality of our eggs decline. They decline gradually until we reach our mid 30’s when the decrease gets much steeper. So, as we get older our fertility goes down.

GENETICS:  There is a link between certain genetic markers and hormone levels that suggests our reproductive lifespan may be very nearly fixed by our genetics, and it is well known that chromosomal abnormalities and genetic diseases can decrease fertility [3]. These are, however, outside of our control, but if you have a family history of genetic disorders then it may be worth discussing this with your GP.

YOUR MEDICAL CONDITIONS: There are links between conditions such as Polycystic ovarian syndrome (PCOS), coeliac disease, diabetes, endometriosis, anaemia, and thyroid disease (to name but a few), and infertility, so if you have any of these conditions or are worried about your fertility then it is best to see your GP to be assessed.

YOUR MEDICATIONS: Some medications can interfere with various aspects of fertility like ovulation, implantation of the egg and functioning of the fallopian tubes. If you are on any regular medications, then it is best to discuss this with your GP before you begin trying to conceive.

ANY PREVIOUS PREGNANCIES: Having been pregnant already means you are less likely to have trouble getting pregnant compared to couples who haven’t had a pregnancy yet.

IF YOU SMOKE: Smoking reduces your chances of pregnancy by 40%, so if you are a smoker then it may be a good idea to get help with stopping.

YOUR ACTIVITY LEVELS: Studies show exercise boosts fertility, reducing risk of ovulation problems and risk of miscarriage. In addition, if you are regularly active then you are less likely to have pregnancy related side effects like back pain and swollen ankles, and furthermore, being fit helps you to cope better with childbirth.

SEXUAL ACTIVITY: It may seem obvious, but timing and frequency of sexual intercourse affects your chance of a successful pregnancy, with higher chances if you have sex regularly (2-3 times per week) rather than once per week.

YOUR BODY SIZE: Much of the existing research on fertility considers those who are overweight or obese to be at a higher risk of infertility, however, being underweight actually carries the highest risk of infertility [4]. Many guidelines suggest that being within the healthy BMI range of 20-25kg/m2 may improve your chances of conception, and therefore some weight gain or weight loss might be appropriate.  Having said that however, you don’t need to focus on weight to ensure your diet contains all the nutrients required for maximum fertility. You can get pregnant and be under or over-weight, what’s important is your reproductive function, having a regular period, ensuring your body is receiving all the building blocks for a healthy pregnancy to occur.

What is the best way to eat for optimum fertility?

There are several factors to consider, work your way through this list and see what you might need to work on.

First of all…. make sure you are eating enough

If you are not consuming enough calories then reproductive function is one of the first things to suffer, with women experiencing a loss of their period, known as amenorrhea, in times of low-calorie intake and starvation [5].

For the majority of women trying to conceive dieting is inappropriate because it may mean cutting out foods or food groups which could lead to nutritional inadequacies or deficiencies. So actually, ensuring you are eating well and enough is the backbone to good nutrition for fertility.

Are carbs really evil?

There’s probably the most varied advice around carbohydrates and fertility. You may have heard to cut back on sugar or even cut out carbohydrates altogether! Well, the research actually suggests that having plenty of whole grains and fibre may be beneficial for fertility, so a blanket ban on carbs isn’t the best idea.

What’s more important is choosing the right carbs, and those with a low glycaemic index, or GI, (this is a measure of how quickly individual foods increase your blood sugar) and high in fibre would be the best choices [6,7].  So, this means eating lots of whole grains like oats, quinoa and barley, as well as wholegrain breads, wholemeal pasta, beans and pulses.

There is, however, some recent research to suggest that sugary drinks are detrimental to fertility, so cutting back on sugar-sweetened beverages could be a good idea if these are something that you tend to have [8,9].

What’s the best type of protein?

Most of us already eat plenty of protein, and the research suggests that avoiding high protein intakes may be a good thing for fertility [10,11].

Again, what may be more important is which proteins we choose and going for plant-based proteins over animal proteins may help – so this means focusing on lentils, beans and pulses, as well as nuts and seeds instead of meat, perhaps aiming to go plant-based one or two days a week.

Should I cut back on fat?

Healthy fats and oils play a really important role in reproduction and so having the right fats in your diet is essential when optimising fertility. Having plenty of omega-3 fatty acids and monounsaturated fats, while reducing trans fats appears to have the most benefits [12,13,14].

So, this means plenty of oily fish, avocados, nuts and seeds and cutting back on fried foods and highly processed foods such as burgers, sausages, pies, pastries, cakes and biscuits.

It is important to note though if you are having lots of fish and seafood, be sure to choose options that are low in mercury [15].

What’s the deal with soy?

Another controversial one here, soy has been said to be negative for reproductive health because of its high phytoestrogen content, however the evidence actually suggests that soy could have a positive effect on fertility, especially for those going through artificial reproduction therapy [16,17].

What vitamins and minerals should I take when trying to have a baby?

It is recommended that anyone trying for a baby takes a pre-natal supplement to include 400mcg folic acid, not only in order to prevent neural tube defects such as spina bifida, but also to reduce infertility. In addition you’ll need 10mcg of vitamin D.

Other important micronutrients include iron, choline and iodine, as well as those with anti-oxidant properties such as vitamin C, E, zinc and selenium. For many of these nutrients, your diet can provide you with enough as long as you are having plenty of fruits and vegetables (aim for your 5 or even 10-a-day, if you are feeling adventurous), wholegrains and plant-based foods.

Overall dietary patterns

Overall, the best way of eating when it comes to optimum fertility, seems to be in line with a Mediterranean Diet [18]. This means plenty of wholegrains, unsaturated fats, vegetables, fruits, fish, nuts and seeds, legumes, olive oil, and a low intake of meat.

Is there such a thing as the “fertility diet”?

If you have done your own internet searching around diet and fertility, then I am sure you will have seen the term ‘Fertility Diet’.

The official definition of this comes from some research done in 2007 where a diet made up of lots of mono-unsaturated fats, reduced trans fats, lots of plant based proteins and reduced animal proteins, high-fat dairy, low GI carbohydrates and lots of high fibre whole grains, alongside a multivitamin was found to reduce risk of infertility [4].

Many of these dietary factors are discussed above and would largely make up a Mediterranean style of eating.

Should I become a vegetarian?

Although there is research showing that vegetarian diets have beneficial effects on our health overall, and that having more plant-based proteins may be good for fertility [11], following a vegetarian diet can be restrictive and lead to deficiencies if not planned well, and this may affect menstrual cycles or cause lower oestrogen levels [19].

If you are interested in becoming a vegetarian then it is a good idea to see a Registered Dietitian for guidance on ensuring you are having a well-planned nutritionally adequate vegetarian diet, which may not be detrimental to fertility [20].

Ok, but is there anything I should avoid?

We know that having a lot of alcohol and caffeine can be problematic when you are pregnant, but what about when you are trying to conceive?

Alcohol:

In the UK (and many other countries) the advice is: “if you’re pregnant, or planning to become pregnant, the safest approach is not to drink alcohol at all to keep risks to your baby to a minimum”.

This is because alcohol may affect fertility and reduce the chances of getting pregnant by disrupting menstrual cycles and causing changes in ovulation, as well as decreasing sex drive.

However, there is mixed research out there and so a firm conclusion cannot be made either way.

One thing we know for sure is that alcohol affects the development of the foetus and that heavy drinking can lead to developmental malformations in the unborn baby because alcohol easily crosses the placenta and enters the amniotic fluid to reach the foetus [21]. For this reason, heavy drinking during the peri-conception phase should be avoided. For many couples it takes a while to get pregnant, and you may be pregnant before you realise you are.

Caffeine:

Again the connection between caffeine and fertility is not clear from the research, however it is thought that excessive intakes of caffeine may reduce your chances of getting pregnant and increase risk of spontaneous miscarriage [22] and so recommendation are to play it safe and stick to less than 200-300mg caffeine per day, ideally even as low as 100mg per day. This means limiting your coffee and tea intake, or choosing decaf sometimes, and also cutting back on some soft drinks, energy drinks and chocolate too, when you are trying for a baby.

There is over 200mg caffeine in a coffee shop coffee, 100mg caffeine in filter or pod coffee, 50mg caffeine in a cup of tea and 40mg in a can of cola.

What else can I do?

In addition to nutritional factors, other lifestyle choices are important in improving your fertility. These include:

Being active:

We all know that exercise is beneficial for our health generally, but moderate amounts of physical activity have specifically been shown to increase fertility [23].

It is important however to avoid extreme exercise behaviours, as high intensity activity has the opposite effect and may reduce fertility [24-Fertility Society 2016], as does being inactive and sedentary [25].

Around 30-60 minutes of moderate exercise 4 or 5 times per week (or 150 minutes over 7 days) is the general recommendation for health.

Reducing stress:

Anyone having trouble conceiving will tell you what a stressful time it can be, and unfortunately this stress only adds to fertility problems. Studies have shown that stress and tiredness is associated with reduced fertility, specifically taking longer to conceive, and also that infertility is more common in those with depression and anxiety.

So finding ways to relax, reduce stress and improve your mental health may help achieve a healthy pregnancy [26,27].  

Perhaps start by practicing yoga or mediation as well as trying to get enough sleep.

Stop smoking:

If you are a smoker, then this is the first habit you should change. Smoking reduces fertility by up to 40%, increasing the time it takes to get pregnant and, should you fall pregnant then smoking increases your risk of miscarriage.

Get medical advice:

For anyone with health conditions or symptoms they are worried about, such as diabetes, PCOS, thyroid problems etc or if you are taking regular medications then it is a good idea to arrange an appointment with your GP or gynaecologist to set you up.

Summary

So, if you are ready to start trying for a baby, or you have already started and are struggling, why not work your way through the checklist below which summarises everything recommended above in order to achieve a healthy pre-pregnancy diet and lifestyle:

• Take your prenatal vitamins (these must contain folic acid and vitamin D)

• Have a healthy diet in line with the Mediterranean style way of eating including

o   Plenty of fruit and veg

o   Oily fish

o   Wholegrains, nuts and seeds

o   Plant-based proteins such as beans, pulses and legumes

o   Less meat

o   Less sugary drinks

• Cut back on alcohol and caffeine

• Move your body everyday

• Manage your stress levels

• Quit smoking

• Seek medical advice if you have any concerns about your health impacting your fertility.