LiveLighter: Weight, fertility & pregnancy health

Download the PDF (147 KB)

Produced by LiveLighter for Fertility Week 2015
Last updated September 2015

The prevalence of obesity is increasing at alarming rates in Australia. Obesity in both females and males significantly increases the risks of infertility and is associated with greater usage of costly fertility treatments.

If you are trying to get pregnant, or are going to start trying, achieving a healthy weight or getting closer to it increases your chance of conceiving (getting pregnant) and having a healthy baby. These facts can assist in your family planning and help with your efforts towards achieving a healthy weight.

What is the ideal weight for conception?

The ideal weight for conception is different for everyone. Body mass index (BMI) is a number based on your height and weight. The healthy BMI range is between 18.5 and 24.9. If you don’t know your BMI, you can find out at the LiveLighter website.

Being overweight

Compared with women in the healthy weight range, women who are carrying extra weight are less likely to conceive. They are also more likely to take more than a year to get pregnant. Being overweight can affect your fertility by causing hormonal imbalances and problems with ovulation (releasing an egg from the ovaries). Obesity is also associated with Polycystic Ovary Syndrome (PCOS), a common cause of subfertility or infertility. See the Your Fertility website and the Jean Hailes Foundation for Women’s Health website for more information on PCOS.

The environment in which eggs and sperm develop also influences the future baby’s health. Having a lot of extra body fat is harmful to this environment. Getting into shape before conception increases the chance of the baby being healthy at birth and into adulthood.

Not only does obesity increase the likelihood of infertility, it is well documented that obesity and excess weight gain during pregnancy is associated with an increased risk of adverse maternal and foetal outcomes. A number of pregnancy complications are associated with the mother being overweight or obese. This includes increased risk of miscarriage, high blood pressure, pre-eclampsia, gestational diabetes, infection, blood clotting, need for induction of labour, Caesarean birth and stillbirth. Babies born to overweight or very overweight mothers have increased risk of childhood obesity and long term health problems.

If your BMI is above the healthy range it is important to remember that even a modest weight loss will increase your chance of conceiving and having a healthy baby.

Being underweight

Having a BMI under 18.5 is considered underweight. Being underweight can reduce a woman’s fertility by causing hormone imbalances that affect ovulation and thereby the chance of getting pregnant. Compared to women in the healthy weight range, underweight women are more likely to take more than a year to get pregnant. If you are underweight and trying to conceive, an accredited practicing dietitian can help you put on weight. Dietitians Association of Australia (DAA) and Better Health Channel have helpful information for gaining weight.

Weight and male fertility

Being very overweight, can also affect a man’s fertility. For men, getting into shape at least three months before conception can improve the chance of conception and the health of the future baby.

Getting ready for pregnancy

If you are planning to get pregnant it is best to start a healthy eating and exercise plan now to increase the odds of getting pregnant and having a healthy baby. By making healthy changes to your diet and increasing your daily physical activity, you’ll be on your way to a healthy weight.

– Small steps to a healthy weight:Swap sugary drinks and alcohol for waterEat fast food less often and make healthier choices when you canMake half your plate vegetables at lunch and dinner

– Use a smaller plate to help reduce your portion sizes

– Get moving every day

– Fit in regular physical activity like walking to the shops, taking the stairs and walking with a friend

– Spend less time sitting by getting up regularly while using a computer or mobile device and swapping ‘screen time’ for other activities

– Choose healthy snacks like fruit, low fat yoghurt or a small portion of plain nuts

– Choose reduced-fat dairy and lean meat

– Set a realistic weight goal- it can help you feel motivated and active. Aiming for weight loss, 0.5-1 kg per week is a good goal

– Start a healthy eating and exercise plan together with your partner to increase the odds of getting pregnant and having a healthy baby.

It’s good to remember that making these lifestyle changes are good for you, even if they don’t lead to weight loss or you are already a healthy weight. For more help on how to get started you may want to look at the LiveLighter top tips, healthy recipes or the meal and activity planner.

Please note: This fact sheet is about losing weight before getting pregnant. If you’re already pregnant and want to lose weight it’s important to talk to your doctor or a dietitian first.