Most pregnant women need about 1,800 calories per day in the first trimester, rising to around 2,200 in the second and 2,400 in the third. That works out to roughly 300 extra calories per day compared to pre-pregnancy needs, though the increase isn’t spread evenly across all nine months.
Calorie Needs by Trimester
Your body doesn’t need much extra fuel in early pregnancy. During the first trimester, the energy cost of building new tissue is only about 85 extra calories per day, which is barely a snack. Most of the heavy lifting happens later, when the fetus is growing rapidly and your body is expanding its blood volume, building the placenta, and storing energy for breastfeeding.
Here’s how calorie needs typically break down for a normal-weight woman carrying one baby:
- First trimester: about 1,800 calories per day (little to no increase over pre-pregnancy)
- Second trimester: about 2,200 calories per day (roughly 285-340 extra)
- Third trimester: about 2,400 calories per day (roughly 450-475 extra)
These numbers assume a normal pre-pregnancy weight and moderate activity level. The total extra energy cost of a full pregnancy is roughly 77,000 calories, with the bulk of it concentrated in the second and third trimesters when fat and protein are being deposited at the highest rates. About 80% of fetal protein deposition happens in the third trimester alone, which is why calorie needs peak during those final months.
How Your Starting Weight Changes the Math
Your pre-pregnancy BMI is the single biggest factor in determining how many extra calories you actually need. Women who start pregnancy at a higher weight already have larger energy reserves, so the recommended increase is smaller. The CDC provides these calorie adjustments for women who begin pregnancy with obesity (BMI of 30 or above): no extra calories in the first trimester, about 200 extra per day in the second trimester, and about 400 extra per day in the third.
Weight gain targets also shift based on BMI:
- Underweight (BMI under 18.5): 28 to 40 pounds total
- Normal weight (BMI 18.5 to 24.9): 25 to 35 pounds
- Overweight (BMI 25.0 to 29.9): 15 to 25 pounds
- Obese (BMI 30.0 to 39.9): 11 to 20 pounds
These ranges come from the Institute of Medicine and are used by the CDC as the current standard. Gaining within these ranges is associated with the lowest risk of complications for both the mother and baby. Gaining too little can restrict fetal growth, while gaining too much raises the risk of gestational diabetes, high blood pressure, and a larger baby that complicates delivery.
Carrying Twins or Multiples
If you’re pregnant with twins, you need roughly double the calorie increase of a singleton pregnancy, not double the total calories. Brigham and Women’s Hospital recommends adding 300 calories per baby in the first trimester, 340 per baby in the second, and 452 per baby in the third. For twins, that means an extra 600 calories per day early on, climbing to about 900 extra by the end of pregnancy.
Weight gain targets for twins are also significantly higher. A normal-weight woman carrying twins should aim for 37 to 54 pounds total, compared to 25 to 35 for a single baby. Women starting pregnancy overweight should target 31 to 50 pounds with twins, and those with obesity should aim for 25 to 42 pounds.
Where Those Extra Calories Go
It’s easy to assume the extra food is all going to the baby, but the fetus accounts for only part of the equation. Your body deposits protein across several tissues: about 42% goes to the fetus, 17% to the uterus, 14% to your expanded blood supply, 10% to the placenta, and 8% to the breasts. Fat storage follows a similar pattern, with your body banking energy reserves throughout pregnancy (11% in the first trimester, 47% in the second, and 42% in the third).
Your basal metabolic rate, the energy your body burns just to keep functioning, also rises as pregnancy progresses. By the final month it can be noticeably elevated above pre-pregnancy levels. This is your body working harder to circulate a larger blood volume, maintain a higher core temperature, and support a fully developed fetus. After delivery, metabolic rate drops back to normal within about a week and a half.
What to Eat, Not Just How Much
Calorie quantity matters, but so does composition. Current guidelines recommend at least 175 grams of carbohydrates per day during pregnancy (some researchers have proposed raising that to 220 grams to account for the placenta’s glucose needs). Carbohydrates should make up roughly 45% to 65% of your total calories, with the remainder split between protein and healthy fats.
Protein needs rise significantly during pregnancy, particularly in the second and third trimesters when fetal tissue is growing fastest. Whole grains, lean meats, eggs, legumes, and dairy products are practical ways to hit both your protein and carbohydrate targets without relying on empty calories. The “eating for two” idea is technically true, but the second person only needs a few hundred extra calories, not an entire second meal. An extra 300 calories looks like a cup of yogurt with fruit and granola, or a slice of whole-grain toast with avocado and an egg.
Active Women and Calorie Adjustments
The baseline recommendations of 1,800, 2,200, and 2,400 calories per trimester assume a moderately active lifestyle. If you were very active before pregnancy and continue exercising (which is generally encouraged for uncomplicated pregnancies), you may need additional calories beyond these numbers to avoid an energy deficit. There’s no single formula for this, but tracking your weight gain against the recommended ranges is the most practical way to tell if you’re eating enough. If your weight gain falls below your target range, you likely need more fuel. If it’s consistently above, you may be overshooting.
The quality of those extra calories matters more during pregnancy than almost any other time. Your body is building an entire organ (the placenta), expanding your blood volume by nearly 50%, and constructing a fully formed human being. Nutrient-dense foods do that work far more effectively than processed snacks with the same calorie count.