While you can expect to gain weight throughout pregnancy, most of it will occur in the second and third trimesters. In fact, you don’t need to take in any additional calories during the first three months.
That said, there’s no one-size-fits-all recommendation, and it’s OK to gain a little weight during the first trimester. Here’s what you should know about first trimester weight gain.
How much weight should I gain in the first trimester?
If you’re starting at a healthy weight, you only need to gain between 1 to 4 pounds during the first trimester. (This number is a little more for those carrying twins.) Since your blood volume will be increasing during this time, you might gain a few pounds without upping your calorie intake.
Having said that, some people don’t gain any weight (or may even lose a bit!) the first few months, thanks to morning sickness or food aversions. This is usually nothing to worry about unless it continues through the second trimester and into the third.
And if you gain a little more than the recommended amount, don’t worry too much. Some people gain more early on and then stall for a few weeks, while others won’t start gaining weight until the second trimester.
Why don’t I need to gain much during the first trimester?
The main reason you don’t need to gain much weight early on is that your baby starts out microscopic. And by the end of the first trimester, a fetus is only about 2.5 inches long. At this stage, “eating for two” is more like “eating for 1.002.”
Gaining weight is more important during the second and third trimesters. From weeks 13 and beyond, you can expect to gain about a pound a week until you give birth. This usually comes out to around 340 extra calories a day in the second trimester and then 450 extra calories in the third. If you’re starting out underweight or overweight, your healthcare provider might recommend gaining slightly more or less than a pound a week.
In the end, it’s best not to stress over every pound and calorie. As long as you follow your nutrition targets and check in regularly with your healthcare provider, you should be good to go.
Reviewed by the Ovia Health Clinical Team
- “Weight Gain During Pregnancy.” Centers for Disease Control and Prevention (CDC). CDC. December 7, 2020. https://www.cdc.gov/reproductivehealth/maternalinfanthealth/pregnancy-weight-gain.htm.
- Mayo Clinic Staff. “Pregnancy weight gain: What’s healthy?” Mayo Clinic. Mayo Clinic. January 4, 2020. https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/pregnancy-weight-gain/art-20044360.
- “Weight Gain During Pregnancy.” March of Dimes. March of Dimes. September 2020. https://www.marchofdimes.org/pregnancy/weight-gain-during-pregnancy.aspx.