Pregnancy is one time when standard ideal weight calculations do not apply. Your body is growing a human, and that requires additional weight. But how much weight gain is healthy? Too little can harm your baby's development; too much increases risks for both of you.
This guide breaks down the current medical recommendations for pregnancy weight gain, explains what the extra weight consists of, and provides practical tips for staying within healthy ranges throughout your pregnancy journey. If you're trying to conceive, our ovulation calculator can help you find your fertile window, and once pregnant, the pregnancy due date calculator will help you track your progress.
Why Pre-Pregnancy Weight Matters
Your recommended weight gain during pregnancy depends heavily on where you started. Women who begin pregnancy underweight need to gain more; women who begin overweight or obese need to gain less. This is because your body already has (or lacks) fat stores that affect how much additional energy reserve you need for pregnancy and breastfeeding.
Before getting pregnant, knowing your ideal weight and BMI helps you understand which weight gain category applies to you.
Recommended Weight Gain by Pre-Pregnancy BMI
The following guidelines come from the Institute of Medicine (IOM) and are endorsed by the American College of Obstetricians and Gynecologists (ACOG):
| Pre-Pregnancy BMI | Category | Recommended Total Gain | Weekly Gain (2nd/3rd Trimester) |
|---|---|---|---|
| Under 18.5 | Underweight | 28-40 lbs (13-18 kg) | 1-1.3 lbs |
| 18.5-24.9 | Normal | 25-35 lbs (11-16 kg) | 0.8-1 lb |
| 25.0-29.9 | Overweight | 15-25 lbs (7-11 kg) | 0.5-0.7 lb |
| 30.0+ | Obese | 11-20 lbs (5-9 kg) | 0.4-0.6 lb |
For Twin Pregnancies
Carrying multiples requires more weight gain:
- Normal BMI: 37-54 lbs
- Overweight: 31-50 lbs
- Obese: 25-42 lbs
Where Does the Weight Go?
Pregnancy weight gain is not all fat. Here is approximately where those 30 pounds go for a woman at healthy pre-pregnancy weight:
| Component | Weight |
|---|---|
| Baby | 7-8 lbs |
| Placenta | 1-2 lbs |
| Amniotic fluid | 2 lbs |
| Uterus growth | 2 lbs |
| Breast tissue | 2 lbs |
| Increased blood volume | 4 lbs |
| Extra fluid | 4 lbs |
| Fat stores | 7-8 lbs |
| Total | 29-32 lbs |
The fat stores serve an important purpose: they provide energy reserves for breastfeeding and recovery. This is why some weight gain beyond the baby and pregnancy tissues is necessary and healthy.
Trimester-by-Trimester Guide
First Trimester (Weeks 1-12)
Expected gain: 1-5 pounds total
Weight gain in the first trimester is typically minimal. Many women actually lose weight due to morning sickness. This is generally not a concern unless weight loss is severe or prolonged.
What is happening:
- Baby is tiny (about the size of a lime by week 12)
- Placenta is forming
- Blood volume begins increasing
- Hormonal changes may cause bloating (not true weight gain)
Calorie needs: No additional calories needed in the first trimester. Focus on nutrient-dense foods and managing nausea.
Second Trimester (Weeks 13-26)
Expected gain: About 1 pound per week (less if overweight/obese)
This is when most women start gaining weight more steadily. Morning sickness typically subsides, appetite returns, and the baby grows rapidly.
What is happening:
- Baby grows from lime-sized to about 2 pounds
- Amniotic fluid increases
- Breast tissue develops
- Blood volume continues expanding
Calorie needs: Approximately 340 extra calories per day (equivalent to a small meal or two snacks).
Third Trimester (Weeks 27-40)
Expected gain: About 1 pound per week (less if overweight/obese)
Weight gain continues at a similar pace, though it may slow in the final weeks. Some women gain more in the early third trimester and less toward the end.
What is happening:
- Baby gains most of its birth weight
- Fat stores increase for breastfeeding
- Fluid retention often increases
- The baby "drops" into position late in pregnancy
Calorie needs: Approximately 450 extra calories per day.
Risks of Gaining Too Much
Excessive weight gain during pregnancy is associated with:
- Gestational diabetes: High blood sugar that develops during pregnancy
- Preeclampsia: Dangerous high blood pressure condition
- Larger baby (macrosomia): Increases risk of difficult delivery and C-section
- Preterm birth: Baby born before 37 weeks
- Postpartum weight retention: Difficulty losing weight after delivery
- Future obesity: Both mother and child have higher long-term obesity risk
Risks of Gaining Too Little
Insufficient weight gain also carries risks:
- Low birth weight baby: Under 5.5 pounds, associated with health problems
- Preterm birth: Baby born too early
- Developmental issues: Baby may not get enough nutrients for optimal growth
- Breastfeeding difficulties: Inadequate fat stores can affect milk supply
Tips for Healthy Pregnancy Weight Gain
Eat Nutrient-Dense Foods
Pregnancy is not the time to "eat for two" in terms of quantity, but it is the time to focus on quality. Every bite should count nutritionally.
- Protein: Aim for 75-100 grams daily from lean meats, fish, eggs, dairy, legumes
- Folate: Essential for neural tube development - leafy greens, fortified cereals, beans
- Iron: Supports increased blood volume - lean red meat, spinach, fortified cereals
- Calcium: For baby's bone development - dairy, fortified plant milks, leafy greens
- DHA: For brain development - fatty fish, DHA-fortified eggs
Stay Active
Unless your doctor advises otherwise, moderate exercise during pregnancy is safe and beneficial:
- Aim for 150 minutes of moderate activity per week
- Walking, swimming, and prenatal yoga are excellent choices
- Avoid contact sports, activities with fall risk, and exercising on your back after the first trimester
- Listen to your body and modify as needed
Stay Hydrated
Hydration is especially important during pregnancy. Dehydration can cause contractions, constipation, and worsen swelling. Calculate your needs with our Water Intake Calculator - pregnant women typically need 8-12 cups daily.
Track But Do Not Obsess
Weigh yourself weekly at the same time (morning, after using the bathroom). Track trends rather than daily fluctuations, which can vary by several pounds due to water retention, digestion, and other factors.
Address Cravings Wisely
Cravings are normal, but constant indulgence leads to excessive gain. Strategies include:
- Allow small portions of craved foods rather than fighting cravings entirely
- Find healthier versions of craved foods when possible
- Ensure you are eating enough at meals so cravings are not driven by hunger
- If craving non-food items (pica), tell your doctor immediately - this can indicate nutritional deficiency
When to Talk to Your Doctor
Contact your healthcare provider if:
- You gain more than 3 pounds in one week (could indicate fluid retention/preeclampsia)
- You lose weight after the first trimester
- You are significantly under or over recommended weight gain
- You have severe morning sickness preventing adequate nutrition
- You develop unusual cravings for non-food items
Postpartum: Returning to Your Ideal Weight
After delivery, you will lose weight in stages:
Immediately After Birth
You will lose approximately 10-13 pounds right away (baby, placenta, amniotic fluid, some blood and fluid).
First Few Weeks
Additional fluid weight drops as your body releases the extra blood volume and water retention. This can be another 5-10 pounds.
Gradual Return
The remaining weight - primarily fat stores - takes longer to lose. Most women return to within a few pounds of pre-pregnancy weight by 6-12 months postpartum.
Breastfeeding Considerations
Breastfeeding burns approximately 300-500 extra calories daily, which helps with weight loss. However, it also increases hunger and fluid needs. Wait until at least 6-8 weeks postpartum before actively trying to lose weight, and ensure adequate calorie intake (typically 1,800-2,000 minimum) to maintain milk supply.
Learn more about BMR during pregnancy and postpartum to understand your calorie needs during this time.
After Pregnancy: Finding Your New Ideal Weight
Your body may settle at a slightly different weight after pregnancy, and that is normal. Factors include:
- Permanent changes in hip width and breast tissue
- Changes in muscle mass and distribution
- Metabolic changes from pregnancy and breastfeeding
- Age-related metabolism shifts
Use our Ideal Weight Calculator as a general guide, but be patient with your body. It took nine months to gain the weight; give yourself at least that long to lose it.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Every pregnancy is different. Always follow your healthcare provider's specific recommendations for your situation.
Frequently Asked Questions
How much weight should I gain during pregnancy?
It depends on your pre-pregnancy BMI. If you started at a healthy weight (BMI 18.5-24.9), aim for 25-35 pounds total. Underweight women should gain 28-40 pounds, overweight women 15-25 pounds, and obese women 11-20 pounds according to current guidelines.
When do you gain the most weight during pregnancy?
Most weight gain occurs in the second and third trimesters. In the first trimester, you might gain only 1-5 pounds total. After that, expect to gain about 1 pound per week for healthy-weight women, though this varies by pre-pregnancy BMI.
Is it safe to diet during pregnancy?
Restrictive dieting during pregnancy is not recommended as it can deprive your baby of essential nutrients. However, if you are gaining too much, focus on nutrient-dense foods and appropriate portion sizes. Always work with your healthcare provider on any weight concerns.
What happens if I gain too much weight during pregnancy?
Excessive weight gain increases risks of gestational diabetes, preeclampsia, difficult delivery, and having a larger baby. It also makes postpartum weight loss harder. If you are gaining faster than recommended, speak with your provider about adjusting your eating habits.
How quickly should I lose pregnancy weight after delivery?
Most women lose about 10-13 pounds immediately after birth. After that, aim for gradual loss of 1-2 pounds per week if breastfeeding, waiting until 6-8 weeks postpartum to actively diet. It typically takes 6-12 months to return to pre-pregnancy weight.
