Healthy eating and exercise

On average, men who are overweight or obese have lower sperm quality than men who are a healthy weight. Being underweight can also reduce a man’s sperm quality and therefore his fertility.

Being overweight or obese can cause hormonal changes that reduce fertility and make men less interested in sex. Men who are very overweight are also more likely to have problems getting and keeping an erection. Together, these factors reduce the chance of fathering a child.

Being a healthy weight increases your chance of getting pregnant and reduces the risk of complications during pregnancy.

Being underweight can affect your menstrual cycle, making it harder to conceive. And if you are a woman in the obese BMI category, it can take longer to get pregnant and you have a higher risk of:

• miscarriage
• hypertension (high blood pressure)
• pre-eclampsia
• gestational diabetes
• infection
• blood clotting
• the need for medical intervention to bring on labour (induced labour)
• caesarean birth
• premature birth
• stillbirth

Babies born to women who are obese are more likely than babies born to mothers in the healthy weight range to:

• be larger than normal at birth
• need intensive care after birth
• have a birth defect
• become obese and have health problems in childhood and later in life.

What is healthy eating?

If you want to eat a healthy, balanced diet, try eating a Mediterranean-style diet. The Mediterranean diet has lots of fresh vegetables and fruit, whole grains, legumes, fish and olive oil and very little red meat. It’s linked to good health and recommended by nutritionists. Research suggests it can also boost fertility and reduce the risk of gestational diabetes (diabetes that starts in pregnancy).

To get started on the Mediterranean diet:

• Eat more fruits and vegetables. Aim for seven to 10 servings a day of fruit and vegetables.
• Switch to whole-grain bread, cereal and pasta and try other whole grains, such as bulgur and farro.
• Use healthy fats wherever possible. Replace butter with olive oil in cooking and try dipping bread in flavoured olive oil instead of putting butter or margarine on it.
• Eat more seafood. Eat fish at least twice a week but avoid deep-fried fish.
• Reduce red meat and replace it with fish, chicken, or beans. If you eat red meat, make sure it's lean and keep portions small.
• Enjoy some dairy. Low-fat plain yogurt and small amounts of a variety of cheeses are allowed in moderation.
• Limit foods and drinks with lots of sugar in them, including sweet biscuits, cakes, soft drinks and fruit juice.
• Avoid fried foods such as French fries and doughnuts.
• Avoid processed foods such as crisps and crackers.

Changing your diet can be challenging, so we also recommend:

• Avoiding short-term fad diets or changes that you are unlikely to continue in the future.
• Setting small achievable goals that you can manage (e.g. taking the stairs rather than the lift, using a pedometer or smart phone app to count your steps each day, swapping juice or soft drinks for water).
• Being realistic and building your goals up slowly over time.
• It’s best that women planning a pregnancy avoid eating fish that have high levels of mercury, including ling, orange roughy, shark and swordfish, as it can affect their unborn baby’s health. Find out more at Better Health Channel.

Our healthy weight fact sheet and the LiveLighter website offer tips for getting healthier.

The Dietitians  Association of Australia can help you create your personal healthy eating plan.

The Australian Government’s Healthy Weight website has information about a balanced diet and explains how much exercise is recommended to reach or maintain a healthy weight.

What does regular exercise mean?

Experts recommend being active every day to prevent unhealthy weight gain and to maintain a healthy weight. This can be done by either:

• 2.5 to 5 hours of moderate intensity physical activity each week, such as a brisk walk or swimming.
• 1.25 to 2.5 hours of vigorous intensity physical activity each week – such as jogging, aerobics, fast cycling, soccer or netball.
• an equivalent combination of moderate and vigorous activities each week.

You can also include muscle-strengthening activities on at least two days each week, such as:

• push-ups
• pull-ups
• squats or lunges
• lifting weights
• household tasks that involve lifting, carrying or digging.

Doing any physical activity is better than doing none. If you do no physical activity right now, start by doing some, then slowly build up to the recommended amount.

While studies show that exercise boosts female fertility it is important to note that a large amount of very high intensity exercise may actually reduce fertility and the chance of having a baby with fertility treatment. So, it’s a good idea to avoid very high intensity exercise, such as marathon running, while trying for a baby.

For women, unhealthy weight can be associated with a medical condition called polycystic ovary syndrome (PCOS), a common cause of infertility. PCOS is a hormonal condition that affects up to one in seven women of reproductive age. Early diagnosis, a healthy lifestyle and medication can improve fertility for women with PCOS. Find out more about PCOS here.

Diabetes in both men and women affects the chance of having a baby but it can be controlled to reduce or remove symptoms. Men and women with diabetes should have a health check at least three to six months before trying for a baby to review general health and diabetes management.

For more information about how to manage diabetes before and during pregnancy visit the National Diabetes Services Scheme (NDSS) Pregnancy & Diabetes website (for women) and Andrology Australia website (for men).

Find out more about diabetes here.

Relative energy deficiency in Sport is a syndrome that can affect both male and female athletes. It can affect a woman’s menstrual cycle and fertility. RED-S occurs when a person’s energy intake from food and drinks is insufficient to support the energy expenditure required for bodily functions beyond exercise and sporting activities. One sign of RED-S is weight loss. You can read more about it here.

Folate is a B-group vitamin that supports the baby’s brain and spinal cord to develop properly, during the very early stages of pregnancy. It is difficult for women to get enough folate in their diet. Therefore, it is recommended that women take at least 400 micrograms of folic acid each day, starting at least one month before conceiving, and during the first few months of pregnancy. Your doctor will recommend the right dose for you during pregnancy.

You can get folate through a multivitamin tablet; it’s best to take one specifically for pregnancy or pre-conception because some vitamins, such as Vitamin A, are dangerous if taken in high amounts during pregnancy.

Some studies suggest that folic acid supplementation can improve fertility in some people but it is not yet known if this applies to everyone.

Iodine is also important for the baby’s development. Women planning a pregnancy should supplement their diet with 150 micrograms of iodine each day to support the development of the baby’s brain and nervous system.   

It is not known if iodine supplementation directly improves fertility.

Vitamin D supplements may improve fertility in women and men who are vitamin D deficient.

During pregnancy vitamin D is involved in transferring calcium to the growing baby. You can ask your doctor for advice about testing whether you need vitamin D supplements.

Zinc and selenium can reduce the damaging effects of free radicals. Free radicals are waste products from various chemical reactions in the cells in the body. Substances that produce free radicals include fried foods, alcohol, tobacco smoke, pesticides and air pollutants.

High levels of free radicals can cause health problems. Studies of infertile men have found that zinc and selenium can reduce the damage to sperm caused by free radicals and improve sperm quality. Whether this improves their chance of fathering a child is not yet known but it may be a good idea for men who want to be fathers to boost their zinc and selenium intake. The easiest way to do this is through a healthy diet. Supplements are also available from pharmacies.

It is not known if zinc or selenium supplements improve female fertility.

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