How much weight can I gain when I'm pregnant? 

Rebecca McPhee
Dietitian Member of the DAA


3 Minutes

Gaining weight during pregnancy is natural and a vital part of your baby’s development and prepares you for breastfeeding. Whilst losing weight is not recommended during pregnancy, careful attention still needs to be made not to gain too much. 

Studies show that gaining too much weight during pregnancy and too quickly, increases your risk of health problems including diabetes during pregnancy, called Gestational Diabetes, high blood pressure and having a caesarean. We also know from research that even for women in the healthy weight range, a weight gain of more than 2.5% of their body weight prior to pregnancy was associated with 2.7-times higher risk of developing gestational diabetes compared with healthy weight women who did not gain any weight. Gestational diabetes, also puts you and your baby at risk of developing type 2 diabetes in the future. 

 

How much weight is enough? 

The right amount of weight you gain during pregnancy is not a one size fits all approach. It really depends on your BMI (Body Mass Index) before pregnancy. The general rule is that if you are above a healthy weight before pregnancy, you should aim to gain less weight than those who are a healthy weight. Your BMI is calculated as your weight (kg) divided by your height (m)².  

 

Below are recommendations from the Institute of Medicine for total and rate of weight gain during pregnancy, by pre-pregnancy BMI: 

 

Pre-pregnancy BMI 

Total weight gain in kg 

Rates of weight gain* 2nd and 3rd trimester in kg/week 

Underweight (< 18.5 kg/m2) 

12.5 – 18.0 

0.51 (0.44 – 0.58) 

Normal weight (18.5 – 24.9 kg/m2) 

11.5 – 16.0 

0.42 (0.35 – 0.50) 

Overweight (25.0 – 29.9 kg/m2) 

7.0 – 11.5 

0.28 (0.23 – 0.33) 

Obese (≥ 30.0 kg/m2) 

5.0 – 9.0 

0.22 (0.17 – 0.27) 

Weight gain during pregnancy: recommendations for Asian women, by pre-pregnancy BMI 

Pre-pregnancy BMI 

Total weight gain in kg (during pregnancy) 

Weight gain per week in kg (after 12 weeks) 

<18.5 

12.5-18.0 

0.5 

18.5-22.9 

11.5-16.0 

0.4 

23-27.5 

7.0-11.5 

0.3 

>27.5 

≤ 7.0 

  

Reference: Institute of Medicine, 2010 

 

Where does pregnancy weight gain go? 

Ever wondered where the rest of your pregnancy weight goes?! On average, a baby weighs in at around 3 to 3.6 kilograms. That makes up for some of your pregnancy weight gain. What about the rest? Here's a sample breakdown:

  • Larger breasts: 0.5 to 1.4 kilograms 

  • Larger uterus: about 0.9 kilograms 

  • Placenta: about 0.7 kilograms 

  • Amniotic fluid: about 0.9 kilograms 

  • Increased blood volume: about 1.4 to 1.8 kilograms 

  • Increased fluid volume: about 0.9 to 1.4 kilograms 

  • Fat stores: about 2.7 to 3.6 kilograms 

 

How do I prevent gaining much weight? 

How to manage your pregnancy weight will vary from woman to woman. However the following tips are sure ways to help you gain weight at a steady pace.  

 

1. Follow the Australian guideline to healthy eating for pregnancy 

 

Food Group 

Number of serves 

Example of serving size 

Vegetables, legumes/beans 

½ cup cooked vegetables  
½ cup cooked or canned* beans, peas or lentils 
1 cup green leafy or raw salad vegetables 
½ cup sweet corn 
½ medium potato or other starchy vegetables  
1 medium tomato 

Fruit 

1 medium fruit, such as apple, banana, orange 
2 small fruits, such as apricots, kiwi fruits or plums 
1 cup diced or canned fruit (no added sugar)  

Grain (cereal) foods, mostly wholegrain and/or high-fibre varieties 

8 1/2  

1 slice bread, ½ medium roll or flat bread (40 g) 
½ cup cooked rice, pasta, noodles, barley, buckwheat, semolina, polenta, burghul or quinoa 
½ cup cooked porridge, 2/3 cup wheat cereal flakes, ¼ cup muesli 
3 crispbreads 
1 crumpet, small English muffin or scone 

 

Lean meats and poultry, fish, eggs, tofu, nuts and seeds and legumes/beans 

 

3 1/2  

65 g cooked lean meats, such as beef, lamb, veal, pork, goat or kangaroo  
(90–100 g raw) 
80 g cooked lean poultry, such as chicken, turkey (100 g raw) 
100 g cooked fish fillet (115 g raw) or one small can of fish 
2 large eggs 
1 cup cooked or canned* legumes/beans, such as lentils, chickpeas or split peas 
170 g tofu 
30 g nuts or seeds, nut/seed paste* 

 

2. Have a plan 

Do you ever find that when you go to the supermarket without a shopping list, a lot of the non essentials come back with you?! Write out a shopping list before you go and plan a week's worth of meals. You will be surprised at how much money you will also save! 

 

3. Watch the extras 

Discretionary foods, often called 'sometimes' or 'treat' foods are where the kilojoules can pile up and contribute to extra weight gain. Discretionary foods are high in saturated fat and sugars and should be kept to occasioanlly. Basing your diet around the 5 foods groups and planning meals will leave little room for temptation!   

  

4. Get moving 

Including daily physical activity during pregnancy is completely safe as long as you exercise with caution and don't overdo it. Regular physical activity is important for your physical health and wellbeing. Aim for at least 30 minutes most days. 

 

5. Keep in contact with your Doctor 

It is not uncommon for some women to lose weight in the first trimester due to morning sickness. Your Doctor will monitor your weight and if you are struggling to gain the recommended weight for your BMI, an Accredited Pracitising Dietitian can provide you with the advice you need. 

 

6. Keep positive  

Keeping healthy is not just about nutrition and exercise, it is also about having a positive mindset and feeling relaxed. If you are finding it all a little overwhelming, try some of these ideas to calm a worried mind: read a book, go for a walk in the fresh air, meditate, call a friend who you know will make you laugh and give you sound advice, listen to music or get out in the garden. Don't forget to make the most of favours and ask family and friends for help.  

 

In summary 

  • The amount of weight gained during pregnancy depends on your pre-pregnancy BMI. The guidelines set by the Institute of Medicine will outline the amount that is right for you 

  • Gaining too much weight and too quickly can increase your risk of developing gestational diabetes, high blood pressure or having caesarian  

  • Focus your diet around the five food groups and include daily physical activity 

  • Keep in contact with your Doctor if you are worried about gaining too much  or not enough weight 


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