Most pregnant women gain between 25 and 35 pounds over the course of a full-term pregnancy, though the right amount depends on your weight before conception. The guidelines used by doctors today come from the National Academy of Medicine (formerly the Institute of Medicine) and are based on your pre-pregnancy BMI.
Recommended Weight Gain by BMI
Your starting weight is the single biggest factor in how much you should gain. The current guidelines, reaffirmed by the American College of Obstetricians and Gynecologists as recently as 2023, break it down like this:
- Underweight (BMI below 18.5): 28 to 40 pounds
- Normal weight (BMI 18.5 to 24.9): 25 to 35 pounds
- Overweight (BMI 25 to 29.9): 15 to 25 pounds
- Obese (BMI 30 to 39.9): 11 to 20 pounds
The ranges are wide for a reason. A normal-weight woman who is 5’2″ and one who is 5’10” will have different needs even if their BMIs are similar. Your provider will help you find a target within the range that makes sense for your body.
Where the Weight Actually Goes
It can feel like the number on the scale is climbing fast, but only a fraction of that weight is body fat. Here’s a rough breakdown of where about 30 pounds ends up at the end of pregnancy:
- Baby: 7.5 pounds
- Placenta: 1.5 pounds
- Amniotic fluid: 2 pounds
- Uterus growth: 2 pounds
- Breast tissue: 2 pounds
- Extra blood volume: 4 pounds
- Maternal fat stores: 7 pounds
That accounts for about 26 pounds before you even include the extra fluid your body retains, which can add several more. The fat stores aren’t wasted weight. Your body banks that energy specifically to fuel breastfeeding and recovery after delivery.
How Gain Is Spread Across Trimesters
Weight gain isn’t steady from week one. During the first trimester, most women gain only 1 to 4 pounds total, and some actually lose weight due to nausea. The real climb happens in the second and third trimesters, when you can expect to gain roughly a pound per week if you started at a normal weight (slightly less if you started overweight or obese).
Calorie needs reflect this pattern. In the first trimester, you don’t need any extra calories beyond what you normally eat, roughly 1,800 per day for most women. That rises to about 2,200 per day in the second trimester and around 2,400 in the third. The old advice about “eating for two” overstates it significantly. The extra calories in the second trimester are roughly equivalent to a peanut butter sandwich and a glass of milk.
Weight Gain With Twins
Carrying two babies changes the targets substantially:
- Underweight: 50 to 62 pounds
- Normal weight: 37 to 54 pounds
- Overweight: 31 to 50 pounds
- Obese: 25 to 42 pounds
The higher targets reflect the demands of growing two placentas, carrying more amniotic fluid, and supporting a larger blood volume. Women with twins also tend to deliver earlier, so gaining enough weight in the second trimester is especially important for fetal development.
Why Staying in Range Matters
A large meta-analysis of data from 1.6 million women, published in the BMJ, found clear risks on both sides of the recommended range. Gaining too little is linked to higher rates of preterm birth, low birth weight, and respiratory problems in the newborn. Gaining too much raises the likelihood of cesarean delivery, high blood pressure disorders during pregnancy, and having a larger-than-average baby, which itself increases the chance of birth injuries and NICU admission.
These are population-level risks, not guarantees. Plenty of women who gain a few pounds outside the guidelines have uncomplicated pregnancies. But the further you stray from the range, the more the odds shift. If you notice your gain is tracking well above or below the targets at a prenatal visit, that’s worth a conversation rather than a worry spiral. Adjusting eating patterns and activity levels in the second trimester can often bring things back on track.
Losing the Weight After Delivery
About 11 to 13 pounds come off immediately at birth, once you account for the baby, placenta, amniotic fluid, and some blood loss. Over the next few weeks, another 4 to 5 pounds of retained fluid typically disappear on their own as your blood volume returns to normal and your uterus contracts back to its original size.
That still leaves the fat stores your body set aside. For women who breastfeed, those 5 to 6 pounds are gradually used up over the first six months. Most women who gained within the recommended range return to their pre-pregnancy weight somewhere between 6 and 12 months postpartum, though the timeline varies widely and is influenced by sleep, activity level, and whether this is a first or subsequent pregnancy.