Weight gain is important during the second and third trimesters, and it’s a totally normal, essential part of a healthy pregnancy. But many people do find this aspect of pregnancy challenging. The world we live in is not gentle about weight gain or certain body changes. We’re here to offer support and information around some common concerns and questions regarding weight gain during pregnancy. While it’s best to discuss the details of your pregnancy with your doctor, the steps below may help provide some context for those conversations.
During pregnancy, gaining weight at a “healthy rate” will look different from person to person. Usually people gain more weight in the second and third trimesters. This is when blood volume, breast size, and water retention increase. The baby and placenta also grow more at these stages.
Understanding your pre-pregnancy body mass index, or BMI, is the first step toward getting a sense of what the recommended weight gain is for you. You can calculate your pre-pregnancy BMI using the CDC’s calculator or this formula: Weight (lb) / [height (in)]2 x 703
Example: Weight = 150 lbs, Height = 5’5″ (65″)
Calculation: [150 ÷ (65)2] x 703 = 24.96
Once you know your pre-pregnancy BMI, you can use that number to get a sense of how much weight you might want to gain during your second trimester. Weight gain in the second trimester is a strong indicator of total weight gain at the end of your pregnancy.
- BMI of less than 18.5: 20 lbs. (9 kg) by the end of second trimester
- BMI of 18.524.9: 15-20 lbs. (6.8-9 kg) by the end of second trimester
- BMI of 25-29.9: 10 lbs. (4.5 kg) by the end of second trimester
- BMI of 30 or more: no more than 10 lbs. by the end of the second trimester
While your weight gain may slow down a bit during the third trimester, this is when your little one will gain the most weight. Again, you can use your pre-pregnancy BMI to see how much weight you can expect to gain over the course of your whole pregnancy.
- BMI of less than 18.5: 28-40 lbs (12.7 – 18 kg) total at the end of pregnancy
- BMI of 18.5- 24.9: 25-35 lbs (11.3 – 15.9 kg) total at the end of pregnancy
- BMI of 25-29.9: 15-25 lbs (6.8 – 11.3 kg) total at the end of pregnancy
- BMI of 30 or more: 11-20 lbs (5 – 9 kg) total at the end of the pregnancy
If you’re having twins
As you might imagine, weight gain recommendations shift if you’re having twins. As with the benchmarks above, these values are also based on your pre-pregnancy BMI.
- BMI of less than 18.5: 50-62 lbs (22.7-27.7 kg) total at the end of pregnancy
- BMI of 18.5- 24.9: 37-54 lbs (16.8-24.5 kg) total at the end of pregnancy
- BMI of 25-29.9: 31-50 lbs (14-22.7 kg) total at the end of pregnancy
- BMI of 30 or more:: 25-42 lbs (11.3- 19.1 kg) total at the end of pregnancy
If you’re pregnant with triplets or more, or if you’re looking for some more personal weight gain recommendations, speak with your doctor.
Remember, BMI is a very limited measurement of the human body. It is not an indicator of overall health and cannot predict what is and is not healthy for you as an individual person. If you have concerns about your weight at any point throughout your pregnancy, be sure to talk with your healthcare provider. They can listen to any of your feelings or concerns and advise you on what a healthy weight goal looks like for you. If you find it difficult to bring this up, or are struggling with your body changes during pregnancy, it may be beneficial to connect with a dietician who specializes in the Health At Every Size model.
Reviewed by the Ovia Health Clinical Team
- “Weight Gain During Pregnancy: Number 548 (Reaffirmed 2020).” ACOG. American College of Obstetricians and Gynecologists, 11/10/2020. Web.
- “Weight gain during pregnancy.” March of Dimes. March of Dimes, Sept. 2020. Web.
- Mayo Clinic Staff. “Pregnancy weight gain: What’s healthy?” Mayo Clinic. Mayo Clinic, 1/4/2020. Web.