Pregnancy Weight Gain: How Much Is Too Much?

March 29, 2022

Gaining weight during pregnancy is part of the body’s natural effort to grow a healthy baby. It is essential for your baby’s development. But how much is too much? Or too little? The amount of weight a woman should gain depends on a range of factors, including pre-pregnancy weight and other pre-existing conditions. Every pregnancy is different, so every woman will gain a different amount of weight during those nine months. 

Allowing your doctor to guide your weight gain in pregnancy can alleviate concerns and head off any potential issues before they become serious. 

It’s Not All Fat 

Some of the weight you gain is stored fat, but not all of it. A substantial amount of that new  weight is directly related to the baby’s development and the fact that your body is storing and producing more resources to nourish the growing fetus. 

On average, you can expect to gain up to 5 pounds during the first trimester, followed by an additional 1 or 2 pounds each week during the second and third trimesters. Here’s a way to look at what this extra weight includes: 

  • Average baby – 8 pounds

  • Placenta – up to 3 pounds

  • Amniotic fluid – 2 to 4 pounds

  • Uterus growth – 2 to 5 pounds

  • Breast tissue – 2 to 3 pounds

  • Blood supply – 4 pounds

  • Fat, protein and nutrient storage – as much as 9 pounds 

Not Too Much, Not Too Little — Just Right 

Complications can arise when a woman gains too much or too little weight during her pregnancy. 

Gaining less weight than recommended can:

  • Increase chance of miscarriage

  • Increase risk of premature labor

  • Impact breastfeeding success

  • Increase risk of low birth weight

  • Increase risk of infant illness

  • Increase risk of developmental delays

Gaining more weight than recommended can:

  • Complicate labor and delivery

  • Increase possibility of a C-section

  • Increase risk of developing childhood obesity

  • Increase risk of gestational diabetes 

Gaining Too Much or Too Little? You’re Not Alone 

Only about a third of women gain the recommended amount of weight during pregnancy: 21 percent gain too little and 48 percent gain too much. Determining optimal weight gain depends on your pre-pregnancy body mass index (BMI), which factors in both height and weight. The Institute of Medicine offers a free tool to calculate your BMI. The breakdown of recommended weight gain based on BMI: 

  • Underweight (BMI less than 18.5) – 28 to 40 pounds

  • Normal weight (BMI 18.5-24.9) – 25 to 35 pounds

  • Overweight (BMI 25-29.9) – 15 to 25 pounds

  • Obese (BMI over 30) – 11 to 20 pounds 

If you’re expecting multiples, you’ll be advised to gain more weight than if you were carrying one baby. 

Eating Disorders During Pregnancy 

Body dysmorphia — being overly concerned with perceived flaws or defects with your body — is a common issue. Pregnancy, with its myriad of external changes taking hold on the body, can exacerbate the problem. 

Pregnant women with eating disorders are at higher risk of preterm delivery and low birth weight, as well as potential problems with C-section and postpartum depression. But achieving a healthy pregnancy is possible with the right support system in place. 

Counseling is often recommended if you’ve been diagnosed with an eating disorder or body dysmorphic disorder (BDD) and can help if you feel yourself struggling with weight gain and its effect on your appearance. Therapy combines self-observation, self-acceptance and extensive conversation about what to expect with each stage of pregnancy. An OB-GYN will often work in tandem with a mental health specialist to provide counseling and nutritional guidance

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