As the countdown to meeting your baby really kicks into gear you may find yourself with a lot on your mind. Your pregnancy weight gain probably won’t be top on your list of priorities. But it is still important and shouldn’t be totally ignored.
In this final stretch to delivery, maintaining a healthy pregnancy weight gain during the third trimester brings with it benefits to you and the baby. It will also make it easier to lose the extra weight later on. Your future self is eternally grateful!
Weight gain in the third trimester – the importance of BMI
As was the case in the second trimester, the amount of weight you need to gain during the third trimester is dependent on your pre-pregnancy Body Mass Index (BMI).
To calculate your pre-pregnancy BMI, add your height and pre-pregnancy weight into the calculator below and it will work out the BMI for you.
You can use the charts below to see the recommendations from the Institute of Medicine on OVERALL weight gain during pregnancy, depending on your BMI.
For specific details for weight gain in the third trimester, read on.
Single Pregnancy
Twin Pregnancy
Weight gain in the third trimester – will you gain or lose weight?
Weight gain in the third trimester should stay pretty steady during the 7th and 8th months.
During the final month the weight gain may start to slow down. You may even find you lose some weight.
This can be due to all sorts of reasons from reduced water weight (less amniotic fluid in preparation for birth, peeing more, sweating more), to a loss of appetite as you struggle to find the space for food in that ever-expanding belly.
(I, for example, lost almost a kilo – around 2 pounds – during the ninth month of pregnancy).
Remember from the second trimester that although you want to aim for a more or less steady weight gain, unfortunately, it doesn’t always happen in a uniform way. So if you don’t gain anything one week, and then gain 1 kg (2 pounds) the next week it shouldn’t be anything to worry about.
However, if you don’t gain anything for 2 weeks in a row during the 7th and 8th months you should check in with your doctor.
If you have any concerns about your weight gain during pregnancy (too much or too little) make sure to discuss it with your healthcare provider.
How much weight should you gain in the third trimester?
The recommendations for third trimester weight gain are the same as for the second trimester. However as mentioned above, you may find the weight gain slows down. The weight gain even stops or you even lose weight during the ninth month.
The calorie requirements during the third trimester are different though, so read on for all the details.
Underweight BMI pre-pregnancy
If you start pregnancy underweight (BMI less than 18.5), it is recommended that you gain around 0.5 kg or 1 pound each week (maybe slightly more) during the third trimester.
The general recommendation is to add around 400 – 600 calories to your diet each day in the third trimester.
Normal BMI pre-pregnancy
If you start pregnancy at a normal BMI (BMI of 18.5 – 24.9) you will gain around 0.5kg or 1 pound each week in the second trimester.
Add around 500 calories to your diet each day during the third trimester.
Overweight or obese BMI pre-pregnancy
For women who start their pregnancy overweight (BMI of 25 – 29.9) or obese (BMI over 30) it is highly recommended to talk to your doctor about your pregnancy weight gain.
As every pregnancy is different, your doctor may have different recommendations for you compared to the guidelines from the Institute of Medicine.
The guideline from the Institute of Medicine is a weight gain of around 0.2 kg or 0.5 pounds per week during the third trimester for women who start pregnancy at an overweight or obese BMI.
Regarding your daily additional calorie requirements: talk to your doctor. They can give you a goal specific to you.
How much weight should you gain in the third trimester if you are pregnant with multiples?
As was the case in the second trimester, if you are pregnant with multiples, the recommendation from the American College of Obstetricians and Gynaecologists is to add an additional 300 calories per day to the numbers above for each fetus.
That means if you are pregnant with twins, and you started your pregnancy at a normal BMI you would need an extra 800 calories per day (500 calories for a single pregnancy plus 300 to account for one additional baby).
For triplet (or more) pregnancies, or if you started your pregnancy at an overweight or obese BMI then please make sure to discuss with your health care provider so that they can give you individual requirements.
Pregnancy nutrition in the third trimester
The third trimester is when you have the highest energy requirements (i.e. you can eat the most), but at some point you may feel that there just isn’t enough space for all that food!
Remember to try to keep your diet full of whole and nutritious foods, to ensure the baby is getting all the nutrients it needs to grow and thrive.
You could consume the additional calories you need in the third trimester by eating lots of small meals each day, or you might prefer to add some healthy snacks.
If abdominal space is proving to be a challenge, then you might want to choose energy rich foods that are not too filling, such as nuts, seeds, oils, avocados – basically anything with a base of healthy fats. These foods are high in calories, but don’t make you feel bloated.
If you started pregnancy at a normal BMI, you need around 500 extra calories each day during the third trimester.
Check out this link for quick meal ideas at around 500 calories.
Or the extra calories could come from having larger portions at each of your normal meals, plus some snacks throughout the day. Good snack options include:
- Fruit
- Chopped up veggies with hummus
- Nuts or seeds
- Trail mix
- Natural yoghurt and granola
- Nut butters
- Dark chocolate (in moderation)
- Eggs
If you want more general information about weight gain during pregnancy, such as where the weight gain comes from and how to keep your weight gain under control, then check out this post:
For information about weight gain during the first and second trimesters, check out these posts:
When to call the doctor
If you are ever concerned with your pregnancy weight gain, you should check in with your healthcare provider.
It is particularly important to check with your doctor if you:
- Experience a sudden jump up in your weight
- Do not gain any weight for more than two weeks in a row (up to the end of the 8th month)
Sudden weight gain, which doesn’t seem to correspond to overeating can be a sign of preeclampsia (pregnancy related high blood pressure) – so it’s always better to err on the side of caution and get it checked.
Conclusion
During your third trimester you will continue to gain steady weight, particularly in the 7th and 8th months.
The 9th month is very different for every woman. Whilst some women will continue to gain weight, others will actually lose weight, so there is no definite right or wrong here.
The amount of weight you need to gain during your third trimester is dependent on your pre-pregnancy Body Mass Index (BMI), and you should aim for this gain to be steady by following the recommendations for additional calorie consumption.
For multiple pregnancies, or if you started your pregnancy with an overweight or obese BMI (BMI above 25), work with your health care provider to determine your individual weight gain goals for each trimester.
Finally, focus on getting those additional daily calories from nutritious foods to feed your body and your baby with all the nutrients it needs to thrive.
How is your third trimester going? Have you managed to keep your weight gain within the recommended guidelines so far?