What is considered ‘overweight’ or ‘obese’?

Your weight can impact your health, so it’s an important measure of your wellbeing throughout pregnancy. The terms ‘overweight’ and ‘obese’ are defined by a calculation of your height and weight, known as the body mass index (BMI). A pre-pregnancy BMI of between 25 and 30kg/m2 means you’re overweight, while a pre-pregnancy BMI of 30kg/m2 or more indicates obesity.

Measuring your BMI helps your health team advise you on how much weight you should gain during a healthy pregnancy.

What are the complications of being overweight while pregnant?

While many overweight women have healthy pregnancies and healthy babies, there are complications linked to being overweight or obese. Common complications of obesity during pregnancy include:

• Gestational diabetes (high blood sugar levels) — being obese or having a family history of gestational diabetes increases this risk.
• Pre-eclampsia — a medical complication of pregnancy that includes high blood pressure, fluid retention and protein in the urine, and is more common in women with obesity.
• Pelvic pain — being overweight means that you are more likely to have pregnancy-related pelvic pain. This may limit you from moving about normally during pregnancy.
• Influenza (or ‘the flu’) can be concerning for pregnant women, and particularly those with obesity.
• Nutritional deficiencies, such as vitamin D or iron are more common among women with obesity.
• Complications during birth and labour are also more common for women with obesity, and pain relief during labour may be more challenging.

How is obesity and weight gain managed during pregnancy?

If you are concerned about your weight or think you may be overweight, ask your doctor or midwife how they can help you.

Like for all overweight and obese people, the best way to limit or prevent excessive weight gain is by managing how much you eat and increasing how much you exercise. A dietitian can help you with a nutrition plan to suit your nutritional needs, your lifestyle and your specific health conditions. Other health professionals who may be able to help you manage your weight include physiotherapists or exercise physiologists.

How will doctors/midwives manage my pregnancy?

If you are overweight or obese and pregnant, you are more at risk of pregnancy complications, particularly if you have other health conditions as well. Your health team is likely to take some extra precautions.

Examples may include:

• discussions around your weight, and advice on how to manage weight gain during pregnancy
• recommendations for nutritional supplements to suit your circumstance
• ultrasound scans
• vaccination against influenza and COVID-19
• glucose tolerance testing for gestational diabetes, which needs to be done early in pregnancy and may be repeated during pregnancy
• more monitoring for pre-eclampsia
• anaesthetic assessment, in case you will need a caesarean section

Speak with your doctor or midwife and ask about how often you should come in for a pregnancy health check, or if you need to see a specialist obstetrician.

Will being overweight/obese affect my baby?

A baby born to a mother who is obese has an increased risk of long-term health issues including childhood and adult obesity. There are also higher rates of birth defects, stillbirths and neonatal deaths among children of obese mothers.

Remember that even a small amount of weight loss has been shown to improve health outcomes for pregnant women with obesity, as well as their babies. It’s never too late to start taking care of yourself.

What can I do to have a healthy pregnancy?

It is important to create a healthy lifestyle for yourself and for your baby by eating well and exercising frequently.

You should eat a range of vegetables, fruit, wholegrain foods (such as wholegrain bread and crackers), low-fat milk products (such as light milk and low-fat cheese), non-fatty meat and oily fish. These foods give you important vitamins, minerals and proteins to keep your body healthy and functioning well. Eating healthy food means you feel less hungry for ‘junk food’. Make sure you drink enough water — pregnant women should ideally drink 6 to 8 glasses of water each day.

All pregnant women should do physical activity. They should exercise for at least 30 minutes, most days of the week. This can be done at one time or in several shorter sessions. Good exercise options for pregnant women include walking and swimming.

Is it safe to go on a diet or lose weight during pregnancy?

A woman with a pre-pregnancy BMI between 18-24.9 (healthy range) should aim to gain between 11.5-16.0kg while pregnant. An overweight woman should aim to gain around 6.8-11.3kg through pregnancy, while an obese woman should ideally only gain 5.0-9.1kg.

Weight-loss medicines (including prescribed, herbal or non-prescribed medicines) are not recommended during pregnancy.

In cases where a pregnant woman has a BMI of 50 or more, minimal to no weight gain is usually recommended. In most cases, weight loss is not advised during pregnancy. While healthy eating is important, the goal for an obese pregnant woman is not to lose weight, but to limit weight gain during pregnancy.

Who can I speak to?

For more information and trusted guidance, speak to your:

• doctor
• obstetrician
• midwife
• dietitian

Speak to a maternal child health nurse

Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week.