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How to Calculate your pregnancy weight gain
Written by Adejumoke Arinola
Fact Checked by Mindsmaking Professionals24th February, 2025
Why Weight Gain Occurs During Pregnancy?
Weight gain during pregnancy is a natural and necessary process that supports the health of both the mother and the developing baby. It is caused by various physiological changes, including fetal growth, increased blood volume, and hormonal shifts. Understanding why this occurs can help expectant mothers manage weight gain appropriately and ensure a healthy pregnancy.
Factors Contributing to Pregnancy Weight Gain
- Growth and Development of the Baby
A significant portion of pregnancy weight gain comes from the growing baby. By the time of birth, the fetus typically weighs between 6 to 9 pounds (2.7 to 4 kg).
- Increased Blood and Fluid Volume
- The mother’s blood volume increases by 30-50% to supply oxygen and nutrients to the baby.
- Additional fluids, including amniotic fluid, contribute to weight gain.
- Placenta Formation
The placenta, which connects the mother to the baby and provides essential nutrients and oxygen, adds about 1 to 2 pounds (0.5 to 1 kg) to overall weight.
- Uterine and Breast Enlargement
- The uterus expands significantly to accommodate the growing fetus.
- The breasts enlarge in preparation for breastfeeding, adding several pounds.
- Increased Fat Stores
- Pregnancy hormones promote fat storage to provide energy for fetal development and breastfeeding.
- Fat accumulation primarily occurs around the abdomen, hips, and thighs.
- Amniotic Fluid and Other Supportive Structures
- Amniotic fluid, which cushions and protects the baby, adds around 2 pounds (1 kg) to weight gain.
- Additional maternal tissue growth, including muscle and connective tissue, contributes to the overall increase.
Is Excess Weight Gain During Pregnancy a Concern?
While weight gain is necessary, excessive weight gain can increase the risk of:
- Gestational diabetes
- High blood pressure
- Complications during delivery
- Postpartum weight retention
Managing Healthy Weight Gain
To maintain a healthy weight gain:
- Follow a balanced diet rich in protein, whole grains, healthy fats, and vegetables.
- Engage in regular physical activity like walking or prenatal yoga (as advised by a doctor).
- Monitor weight gain through prenatal check-ups.
How much weight gain is considered normal during pregnancy?
The amount of weight gain considered normal during pregnancy depends on a woman's pre-pregnancy Body Mass Index (BMI). The American College of Obstetricians and Gynecologists (ACOG) and the Centers for Disease Control and Prevention (CDC) provide the following guidelines:
Recommended Weight Gain During Pregnancy
Underweight -BMI Range <18.5, Recommended Total Weight Gain 28-40 lbs (12.7-18.1 kg), Rate of Weight Gain in 2nd & 3rd Trimesters 1-1.3 lbs (0.5-0.6 kg) per week
Normal weight - BMI Range 18.5-24.9, Recommended Total Weight Gain 25-35 lbs (11.3-15.9 kg), Rate of Weight Gain in 2nd & 3rd Trimesters 0.8-1 lb (0.36-0.45 kg) per week
Overweight - BMI Range 25-29.9, Recommended Total Weight Gain 15-25 lbs (6.8-11.3 kg), Rate of Weight Gain in 2nd & 3rd Trimesters 0.5-0.7 lbs (0.23-0.32 kg) per week
Obese - BMI Range ≥30, Recommended Total Weight Gain 11-20 lbs (5-9 kg), Rate of Weight Gain in 2nd & 3rd Trimesters 0.4-0.6 lbs (0.18-0.27 kg) per week
Why Does Weight Gain Vary?
- Multiple pregnancies (twins, triplets, etc.) require more weight gain.
- Women with higher BMIs should gain less weight to minimize health risks.
- Weight gain is not linear—it is minimal in the first trimester and increases in the second and third trimesters.
Breakdown of Pregnancy Weight Gain
On average, total pregnancy weight gain is distributed as follows:
- Baby: ~7-8 lbs (3.2-3.6 kg)
- Placenta: ~1.5 lbs (0.7 kg)
- Amniotic fluid: ~2 lbs (0.9 kg)
- Uterus growth: ~2.5 lbs (1.1 kg)
- Breast tissue: ~2-3 lbs (0.9-1.4 kg)
- Increased blood volume: ~4 lbs (1.8 kg)
- Fluid retention: ~3-4 lbs (1.4-1.8 kg)
- Maternal fat stores: ~6-8 lbs (2.7-3.6 kg)
What moms say about pregnancy weight gain
"My body is doing something amazing!" – Some moms appreciate the changes as a sign of their body's strength.
"I didn’t expect to gain this much!" – Others are surprised by how much weight they gain, even when following guidelines.
"I feel beautiful and powerful." – Some women love the way their bodies look during pregnancy.
"I can’t wait to get back to my pre-pregnancy weight." – Many moms feel pressure to "bounce back" after birth.
"Cravings got the best of me!" – Some moms find it hard to resist cravings, leading to more weight gain than expected.
"It’s all worth it for my baby." – Even those who struggle with weight changes often focus on the reward of meeting their little one.
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