Healthy Pregnancy Weight Gain by Trimester
Pregnancy weight gain isn't a straight line. Your body's needs change as your baby grows, meaning your weight gain will happen in phases. Understanding the trimester-by-trimester breakdown helps you know what to expect.
Your weight fluctuates throughout the day. For the most accurate tracking, weigh yourself once a week, in the morning, wearing similar clothing.
First Trimester (Weeks 1-13)
During the first trimester, your baby is tiny—by week 13, they weigh about an ounce. Your body is building the placenta and increasing blood volume, but significant weight gain isn't necessary yet.
- Recommended Gain: 1 to 4.5 lbs total for the entire trimester
- Calorie Needs: No extra calories are needed in the first trimester
- Nausea Factor: Many people lose a little weight due to morning sickness. This is usually not a concern if you stay hydrated.
Second Trimester (Weeks 14-27)
As nausea fades and appetite returns, weight gain steadily increases. Your baby begins to pack on fat, and your body stores energy for nursing.
- Recommended Gain: 1/2 to 1 lb per week (depending on pre-pregnancy BMI)
- Calorie Needs: About 300 to 340 extra calories per day
- Where it goes: Increased blood volume, breast tissue, amniotic fluid, and the growing baby
Third Trimester (Weeks 28-40)
Your baby's weight triples in the third trimester. Weight gain continues steadily but may taper off slightly in the final weeks.
- Recommended Gain: 1/2 to 1 lb per week
- Calorie Needs: About 450 extra calories per day
- Fluid Retention: Mild swelling (edema) is common and can cause minor weight fluctuations
Frequently Asked Questions
Yes! Weight gain often happens in "mini-spurts" followed by plateaus. Always look at the overall trend rather than day-to-day changes.
Slight weight loss from morning sickness is common. Focus on hydration and eating what you can tolerate. Talk to your doctor if you lose more than 5% of your pre-pregnancy weight.