Healthy Weight Gain Throughout Pregnancy

One of my other biggest questions and concerns before we met with a doctor was how much weight I should be putting on and when that should happen. I can’t consider myself to be a slender build, but I don’t really consider myself to be overweight either. If you look at my BMI (26.2) technically I am classified as “overweight,” which has ALWAYS bothered me. I’m built like an athlete. I have big, muscular thighs and butt, which hugely increase my weight. And no, I’m not thin either. I certainly have a little layer of cushioning. My husband and I actually calculated my % body fat a few days ago and it turned out to be 29.1% which is right smack dab in the middle of average for a female. So lets just say I’m comfortable with my weight right now (pre-pregnancy that is).

This first chart depicts healthy and unhealthy BMIs based on your height and weight.


This second chart shows healthy and unhealthy body fat% for both men and women based on your age.


Now, all that being said, when I was in college, I spent a semester abroad in Spain. And I was absolutely miserable. I cried every night, and often during the day. The diet there was heavily meat based (which I find repulsive) and very high in fats, so I was basically eating a really high calorie diet for 3 months. And to top it off, it was cold, rainy and cloudy almost every day that we were there, which I never do well with. Needless to say, I put on about 40 pounds within a 3-month window while I was gone. When I came home, my mom literally did not recognize me, and my grandma asked if I got knocked up while I was gone J Pretty awful. So one of my biggest fears since then has been putting weight back on. I’ve been pretty lucky and have definitely worked hard to avoid it both by diet and exercise. But being pregnant brings a whole new set of weight-based concerns for me. So here’s some research on how much you should put on and when!

I found a couple things to be helpful when looking at this. First, splitting up weight gain by trimester was useful for me. It helped me to understand how many calories I should eat a day which was a big part of my diet plan. Second, looking at the differences between healthy BMI v. over or underweight BMI’s and how that changes weight estimations. A cool study in 2015 looked at weight gain of a random sampling of mothers in the US representing 79% of annual births. It found that 47.5% of all mothers have excessive weight gain during pregnancy. That’s a lot! These numbers were based on weight gain of 28–40 pounds for underweight women, 25–35 pounds for normal-weight women, 15–25 pounds for overweight women, and 11–20 pounds for obese women based on their BMI. Here’s the graph and article that goes with it. Click here to see more specific breakdowns by pre-pregnancy BMI and state.


The concern with excessive weight gain with pregnancy is two-fold for me. One, I don’t want to be a heavy mom (especially because I already know how much more work it is to move when you’re overweight!), and two, there are some serious complications that are correlated with excessive weight gain. Some of these complications include, high gestational birth weight as well as risk of birth injuries (such as brachial plexus injuries) and increased risk of C-section (4% increased risk per 1KG of pregnancy weight gain over the IOM upper limit). This specific study also found that weight gain in the 2nd trimester was more strongly associated with fetal growth than weight gain in the first or third trimester.


  • You should be eating no more calories than whatever is recommended for your weight. Here is a great calculator to see how many calories you should be eating to maintain your body weight. It is not recommended to attempt to lose weight during any point of pregnancy.
  • Or use this site to help calculate your BMI.

First Trimester

  • It is recommended that you continue to eat the same number of calories during the first trimester as you were pre-pregnancy
  • Some sources suggest that by the end of the first trimester you may eat up to 150 calories more than your normal.
  • Throughout the first trimester you should gain from 0-6ish pounds (depending on the source). Many sources say it is not uncommon for women to even lose a pound or two due to severe morning sickness and food aversions.

Second Trimester

  • During the second trimester it is recommended that you eat around 300-340 extra calories a day
  • This should equate to gaining ½ to 1 lb per week for a total of 14 pounds in the second trimester

Third Trimester

  • During the third trimester it is recommended that you eat 450-500 extra calories a day
  • This should equate to gaining between ¾ and 1 lb per week for a total of 10-14 pounds

Total pregnancy gain by pre-pregnancy BMI

  • If you started pregnancy at a healthy BMI (18.5-24.9), you should aim to gain between 25-35 lbs.
  • If you started pregnancy at an underweight BMI (< 18.5) you should aim to gain 28-40 lbs
  • If you started pregnancy at an overweight BMI (25-29.9) you should aim to gain 15-25 lbs
  • If you started pregnancy at an obese BMI (> 30), you should aim to gain 11-20 lbs
  • If you are carrying twins, aim to follow the following
    • Healthy pre-pregnancy BMI – gain 35-45 lbs
    • Underweight pre-pregnancy BMI – gain 40-50 lbs
    • Overweight pre-pregnancy BMI – gain 31-50 lbs
    • Obese pre-pregnancy BMI – gain 25-42 lbs


The IOM guidelines have basically been standard for the past 30 years.

IOM Guidelines    
Weight for height category Recommended total gain in kg’s Recommended total gain in lbs
Low (BMI < 19.8) 12.5-18 27.6-39.7
Normal (BMI 19.8-26) 11.5-16 25.4-35.3
High (BMI > 26) 7-11.5 15.4-25.4

Worried you’ll never be able to lose it after birth? Here’s the breakdown of where all of that weight goes. Great to know that as soon as you give birth, you typically lose around 9-12 lbs. Half way there already!

  • For a typical 30 pound weight gain
    • Baby – 7.5 lbs
    • Placenta – 1.5 lbs
    • Amniotic fluid – 2 lbs
    • Uterine enlargement – 2 lbs
    • Maternal breast tissue – 2 lbs
      • That seems huge!!!
    • Maternal blood volume – 4 lbs
    • Fluids in maternal tissue – 4 lbs
    • Maternal fat and protein storage (important for breast feeding) – 7 lbs

I also really liked this website because it let you plug all of your numbers in and then tells you if you’re on track for weight gain or not.




Margerison-Zilko, Claire E. Et. al. “Trimester of Maternal Gestational Weight Gain and Offspring Body Weight at Birth and Age 5.” Matern Child Health J; 2012: 16.
Abrams, Barbara et. al. “Pregnancy weight gain: still controversial.” Am J Clin Nutr, 2000; 71.


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