By 24 weeks of pregnancy, most people with a normal pre-pregnancy BMI have gained roughly 12 to 17 pounds. That number shifts depending on your starting weight, whether you’re carrying multiples, and how your first trimester went. Twenty-four weeks marks the end of the second trimester, a period when weight gain typically accelerates compared to the slower pace of the first 13 weeks.
Expected Weight Gain by BMI Category
Weight gain recommendations are based on your pre-pregnancy body mass index, and the CDC breaks them into four categories for a single pregnancy:
- Underweight (BMI under 18.5): 28 to 40 pounds total, translating to roughly 14 to 20 pounds by week 24
- Normal weight (BMI 18.5 to 24.9): 25 to 35 pounds total, or roughly 12 to 17 pounds by week 24
- Overweight (BMI 25.0 to 29.9): 15 to 25 pounds total, or roughly 8 to 13 pounds by week 24
- Obese (BMI 30.0 to 39.9): 11 to 20 pounds total, or roughly 5 to 10 pounds by week 24
These mid-pregnancy estimates come from the general pattern of pregnancy weight gain: a small amount in the first trimester (typically 1 to 5 pounds), followed by a steadier rate of about half a pound to one pound per week through the second and third trimesters. If you gained very little or even lost weight during the first trimester due to nausea, your 24-week number may sit on the lower end without any cause for concern.
Why Weight Gain Picks Up in the Second Trimester
The first trimester adds relatively little to the scale. Nausea, food aversions, and the tiny size of the embryo all keep gains modest. Starting around week 14, things change. Blood volume begins increasing substantially, eventually adding 3 to 4 pounds on its own. The uterus grows, the placenta matures, and amniotic fluid accumulates. Your body also starts laying down fat stores, which account for 6 to 8 pounds by the end of pregnancy, serving as an energy reserve for labor and breastfeeding.
By 24 weeks, the baby weighs just over a pound. So most of what you see on the scale is your body doing its job: expanding blood supply, building tissue, and storing fluid. Breast tissue alone can add 1 to 3 pounds over the course of pregnancy, and much of that growth happens during the second trimester.
Weight Gain for Twin Pregnancies
If you’re carrying twins, the targets are significantly higher. The CDC recommends 37 to 54 pounds total for someone starting at a normal BMI, and the gain timeline is front-loaded compared to a singleton pregnancy. By 24 weeks with twins, you may have already gained 24 to 30 pounds or more, and that’s considered appropriate. The ranges for other BMI categories with twins:
- Underweight: 50 to 62 pounds total
- Overweight: 31 to 50 pounds total
- Obese: 25 to 42 pounds total
Twin pregnancies demand faster tissue and blood volume expansion earlier in pregnancy, which is why providers often monitor weight more closely and may set specific gain goals for each trimester.
Risks of Gaining Too Much or Too Little
Staying within the recommended range matters for both you and the baby, and the second trimester is a particularly important window. Gaining significantly more than recommended during this period raises the risk of pregnancy-related high blood pressure. Research published in BMC Pregnancy and Childbirth found that excessive weight gain in the second trimester was associated with roughly 1.5 times higher odds of developing hypertension compared to those gaining within the normal range.
Gaining too little carries its own set of concerns. Insufficient gain during the second trimester is linked to higher rates of abnormal birthweight (about 2.2 times the odds) and an increased risk of preterm delivery, with one study finding the odds of premature birth more than doubled. Inadequate gain was also associated with thyroid-related complications during this period.
These aren’t reasons to obsess over every pound, but they do explain why your provider checks your weight at each prenatal visit. A single weigh-in that falls outside the expected range is rarely concerning on its own. The overall trend matters much more than any individual number.
What Counts as a Normal Pattern
Weight gain during pregnancy is rarely smooth and linear. You might gain 3 pounds in one week and nothing the next. Water retention, meal timing, and even the time of day you step on the scale can create fluctuations of several pounds. What your provider looks for is a general upward trend that roughly matches the expected rate for your BMI category.
A few patterns are worth noting. If you gained very little in the first trimester but are now gaining steadily, you’re likely right on track even if your total looks a bit low at 24 weeks. On the other hand, a sudden spike of 5 or more pounds in a single week, especially with swelling in your hands or face, can signal fluid retention that warrants a closer look. Gradual, consistent gain, even if it doesn’t match the textbook numbers exactly, is the healthiest pattern for most pregnancies.
Where the Weight Actually Goes
It can help to understand that pregnancy weight gain is not primarily fat. By full term, a typical breakdown for someone whose baby weighs 7 to 8 pounds looks like this:
- Baby: 7 to 8 pounds
- Placenta: 1.5 pounds
- Amniotic fluid: 2 pounds
- Uterus growth: 2 pounds
- Breast tissue: 1 to 3 pounds
- Extra blood volume: 3 to 4 pounds
- Extra fluid: 2 to 3 pounds
- Fat stores: 6 to 8 pounds
At 24 weeks, you’re partway through building all of these, with the baby still relatively small and the blood volume and fluid components making up a larger share of your current gain than they will at 40 weeks. The fat stores are accumulating gradually, but the baby’s most rapid growth happens in the third trimester, when you can expect the pace of weight gain to pick up even more.
What to Do if You’re Off Track
If you’re noticeably above or below the recommended range at 24 weeks, small adjustments are more effective than dramatic changes. For those gaining faster than expected, the focus isn’t on dieting or cutting calories. Instead, swapping calorie-dense snacks for nutrient-rich options and staying physically active (walking, swimming, prenatal yoga) can slow the pace without restricting what your body needs.
If you’re gaining less than expected, adding an extra snack or two each day with protein and healthy fats, like nut butter on whole grain toast or a smoothie with yogurt, can help. Some people simply carry smaller and gain less without any issue, especially if they started at a higher BMI. Your provider can use ultrasound measurements to confirm the baby is growing appropriately regardless of what the scale shows.