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Eating a healthy, balanced diet and exercising regularly are two of the best things you can do to improve your overall health and fertility. Both habits contribute to a healthy weight, which increases your chance of a pregnancy and healthy baby.

Women planning a pregnancy should also supplement their diet with folate and iodine – micronutrients that reduce the risk of birth defects such as spina bifida and cleft palate. You can read more about this below.

If you are a man or woman who is overweight or underweight it can take longer to conceive.

Why? For women, it can alter hormone levels that affect the menstrual cycle and egg quality. And for men, it can reduce sperm quality and cause erection problems. Being overweight can also reduce libido (sex drive) for both men and women.

It's not about having a perfect body – just a healthy body, because healthier parents have healthier babies.


A man's weight doesn't affect a couple's ability to have a baby.


On average, men who are overweight or obese are not as fertile as men who are a healthy weight.

  • How can I tell if I’m a healthy weight?

    One way to measure whether you're in a healthy weight range is using the Body Mass Index or BMI. You can enter your height and weight into this BMI calculator to find out your BMI number.

    • A BMI between 18.5 and 24.9 is considered a ‘healthy weight’.
    • A BMI below 18.5 is considered ‘underweight’.
    • A BMI between 25 and 29.9 is considered ‘overweight’.
    • A BMI over 30 is considered ‘obese’.


    You can also measure your waist to indicate whether you have a healthy weight.

  • The facts about weight and fertility

    If you’re not in the healthy weight range, you’re not alone. Most of us carry more weight than our parents and grandparents did when they were our age.

    In 2017-18, two-thirds (67 per cent) of Australian adults were overweight or obese, and obesity is on the rise.

    Many factors contribute to weight gain, including genetics and the environment you live in, so some people gain weight more easily than others. If you want to aim for a healthy weight, assessing your diet and exercise habits can help you get there. You can read more about what a healthy diet consists of, and how much exercise is recommended, below.

  • Weight and male fertility

    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.

  • Weight, female fertility and pregnancy health

    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 you can do

    The good news is, there are changes you can make to aim for the healthy weight range. If you or your partner are overweight or obese, losing even a few kilos can improve your chance of getting pregnant.

    Losing weight is not easy, and it takes commitment and time. But for most people, it is possible. Research shows that if partners get healthier together, there’s a better chance of success. Having support from a partner, family or friend can help you set up healthy lifestyle habits for the future.

    If you are underweight, consult your GP about factors that might be contributing.

    Men who eat a healthy diet and exercise regularly can increase the quality of their sperm. See How to get ready to be a dad and Your Sperm and how to look after them.

  • Ways to make healthier changes
    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.

  • Some medical conditions can affect your weight

  • Polycystic ovary syndrome (PCOS)

    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

    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 (RED-S)

    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.

  • Vitamin and mineral supplements before pregnancy

    Vitamins and minerals (known as micronutrients) are essential for our bodies to function. They occur naturally in the food we eat but can also be taken as supplements.

    A healthy diet is the best way to ensure you're getting the nutrients you need, but it is recommended that women planning a pregnancy supplement their diet with folate and iodine.

    Research shows these micronutrients can reduce the risk of serious birth defects including spina bifida and cleft palate. Some of the following supplements may also help improve fertility. You can talk to your GP for more information about supplements.

  • Folate

    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

    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

    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

    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.

  • References
    • Adane, A. A., et al. (2018). Maternal preconception weight trajectories are associated with offsprings' childhood obesity. International Journal of Obesity, 24(10), 018-0078.
    • Athukorala, et al. (2010). The risk of adverse pregnancy outcomes in women who are overweight or obese. BMC Pregnancy and Childbirth, 10, 56.
    • Bakos, et al. (2011). Paternal body mass index is associated with decreased blastocyst development and reduced live birth rates following assisted reproductive technology. Fertility and Sterility, 95(5), 1700-1704.
    • Best, D., Avenell, A., & Bhattacharya, S. (2017). How effective are weight-loss interventions for improving fertility in women and men who are overweight or obese? A systematic review and meta-analysis of the evidence. Human Reproduction Update, 23(6), 681-705. doi: 10.1093/humupd/dmx027.
    • Brewer, C. J., & Balen, A. H. (2010). The adverse effects of obesity on conception and implantation. Reproduction, 140(3), 347-364. doi: 10.1530/rep-09-0568.
    • Buck Louis, G. M., et al. (2016). Lifestyle and pregnancy loss in a contemporary cohort of women recruited before conception: The LIFE Study. Fertility and Sterility, 106(1), 180-188. doi: 10.1016/j.fertnstert.2016.03.009
    • Campbell, J. M., et al. (2015). Paternal obesity negatively affects male fertility and assisted reproduction outcomes: a systematic review and meta-analysis. Reproductive Biomedicine Online, 31(5), 593-604.
    • Cheney, K., et al. (2018). Population attributable fractions of perinatal outcomes for nulliparous women associated with overweight and obesity, 1990–2014. Medical Journal of Australia, 208(3), 119-125.
    • Chiu, Y.-H., Chavarro, J. E., & Souter, I. (2018). Diet and female fertility: doctor, what should I eat? Fertility and Sterility, 110(4), 560-569.
    • Cleo, G., et al. (2018). Habit-based interventions for weight loss maintenance in adults with overweight and obesity: a randomized controlled trial. International Journal of Obesity. doi: 10.1038/s41366-018-0067-4.
    • Craig, J. R., et al. (2017). Obesity, male infertility, and the sperm epigenome. Fertility and Sterility, 107(4), 848-859. doi:
    • Day, J., et al. (2016). Influence of paternal preconception exposures on their offspring: through epigenetics to phenotype. American Journal of Stem Cells, 5(1), 11-18
    • Dodd, et al. (2011). Maternal and perinatal health outcomes by body mass index category. Australian and New Zealand Journal of Obstetrics and Gynaecology, 51, 136-140.
    • Fullston, T., et al., The most common vices of men can damage fertility and the health of the next generation. Journal of Endocrinology, 2017. 234(2): p. F1-F6.
    • Gaskins, A. J. (2018). Moving the science forward on dietary patterns and male fertility. Fertility and Sterility. doi:
    • Gesink Law, et al. (2007). Obesity and time to pregnancy. Human Reproduction, 22(2), 414-420.
    • Harrison, C. L., et al. (2017). Preventing obesity across the preconception, pregnancy and postpartum cycle: Implementing research into practice. Midwifery, 52, 64-70. doi:
    • Homan, G. F., Davies, M. J., & Norman, R. J. (2007). The impact of lifestyle factors on reproductive performance in the general population and those undergoing infertility treatment: a review. Human Reproduction Update, 13(3), 209-223.
    • Jackson, et al. (2015). The influence of partner’s behavior on health behavior change: The English longitudinal study of ageing. JAMA Internal Medicine, 175(3), 385-392. doi: 10.1001/jamainternmed.2014.7554.
    • Lan, L., et al. (2017). Systematic review and meta-analysis of the impact of preconception lifestyle interventions on fertility, obstetric, fetal, anthropometric and metabolic outcomes in men and women. Human Reproduction.
    • Luke, B., et al. (2011). Female obesity adversely affects assisted reproductive technology (ART) pregnancy and live birth rates. Human Reproduction, 26(1), 245-252.
    • MacDonald, et al. (2013). Body mass index in relation to semen quality and reproductive hormones in New Zealand men: a cross-sectional study in fertility clinics. Human Reproduction, 28(12), 3178-3187. doi: 10.1093/humrep/det379.
    • Marchi, J., et al. (2015). Risks associated with obesity in pregnancy, for the mother and baby: a systematic review of reviews. Obesity Reviews, 16, 621-638. doi: 10.1111/obr.12288.
    • Mutsaerts, M. A. Q., et al. (2014). Effects of paternal and maternal lifestyle factors on pregnancy complications and perinatal outcome. A population-based birth-cohort study: the GECKO Drenthe cohort. Human Reproduction, 29(4), 824-834. doi: 10.1093/humrep/deu006.
    • Nassan, F. L., et al. (2018). Diet and men's fertility: does diet affect sperm quality? Fertility and Sterility, 110(4), 570-577.
    • Nazem TG, Ackerman KE., et al. (2012). The female athlete triad. Sports Health. 4(4):302-311. doi:10.1177/1941738112439685
    • Petersen, et al. (2013). The influence of female and male body mass index on live births after assisted reproductive technology treatment: a nationwide register-based cohort study. Fertility and Sterility, 99(6), 1654-1662. doi: 10.1016/j.fertnstert.2013.01.092.
    • Practice Committee of the American Society for Reproductive, M. (2015). Obesity and reproduction: a committee opinion. Fertility and Sterility, 104(5), 1116-1126. doi:
    • Salas-Huetos, A., et al. (2017). Dietary patterns, foods and nutrients in male fertility parameters and fecundability: a systematic review of observational studies. Human Reproduction Update, 23(4), 371-389. doi: 10.1093/humupd/dmx006.
    • Salas-Huetos, A., et al., Male adiposity, sperm parameters and reproductive hormones: An updated systematic review and collaborative meta-analysis. Obesity Reviews, 2020. 
    • Salas-Huetos, A., et al. (2017). Dietary patterns, foods and nutrients in male fertility parameters and fecundability: a systematic review of observational studies. Human Reproduction Update, 23(4), 371-389. doi: 10.1093/humupd/dmx006
    • Sharma, R., et al. (2013). Lifestyle factors and reproductive health: taking control of your fertility. [Review]. Reprod Biol Endocrinol, 11(66), 1477-7827.
    • Stephenson J, Heslehurst N, Hall J, Schoenaker DAJM, Hutchinson J, Cade JE, Poston L, Barrett G, Crozier SR, Barker M et al. Before the beginning: nutrition and lifestyle in the preconception period and its importance for future health. The Lancet 2018;10.1016/S0140-6736(18)30311-8.
    • Wright, S., & Aronne, L. (2012). Causes of obesity. Abdominal Imaging, 37(5), 730-732. doi: 10.1007/s00261-012-9862-x.


Page created on: 29/08/2018 | Last updated: 19/07/2024

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