Pregnancy weight gain: the ultimate guide

Pregnancy weight gain: the ultimate guide

Pregnancy weight gain is normal, but how much is too much? Here’s what you need to know to guide your nutrition clients through weight gain during pregnancy.

One of the women's most common experiences with pregnancy is naturally occurring weight gain. During this time, gaining weight is crucial, but many women wonder how much is normal and may even seek you out to determine the best foods to eat while pregnant. 

As a nutrition professional, you must provide the right nutrition support to help your clients navigate this time. Not only will this benefit the health of both mom and baby, but it can also mitigate excess weight gain and reduce the risk of pregnancy complications.

In this article, we’re turning to science to better understand how much weight gain is normal, the subsequent health implications, and the best (and worst) foods to eat while pregnant.

Pregnancy weight gain: what is normal?

Weight gain during pregnancy is completely normal. However, too much or too little can have a negative impact on the health of the baby. 


How much weight should you gain during pregnancy?

The U.S. Institute of Medicine (IOM) recommends a weight gain of 11 to 20 pounds (5 to 9 kg) during pregnancy for obese women and 15 to 25 pounds (7 to 11 kg) for overweight women. While the recommended amount of weight gain (or weight loss) for obese pregnant women is still controversial, there have been some revisions for recommended weight gain in the three classes of obesity:

  • Class 1 (BMI of 30-34.9): weight gain of 5 to 15 pounds (2.5 to 7 kg);
  • Class 2 (BMI of 35-39.9): weight gain less than or equal to 10 pounds (4.5 kg);
  • Class 3 (BMI equal to or greater than 40): it has been hypothesized that weight maintenance can be beneficial, but further studies need to be conducted to prove this is true.


Health implications surrounding weight gain

If the mother gains too much weight during pregnancy, this can lead to many complications, such as the risk of miscarriage and stillbirth, gestational diabetes, preeclampsia, cardiac dysfunction, sleep apnea, need for c-sections, and risk of c-section complications. Risks for the baby include birth defects, fetal macrosomia, impaired growth, childhood asthma, and childhood obesity.

Obesity during pregnancy also increases the risk of higher placental weight, vascular dysfunction, inflammation, and changes in placental transporters and mitochondrial activity.

Furthermore, studies have found that 50-60% of overweight or obese women who gain more weight than what is currently recommended are at a higher risk of postpartum weight retention. This can increase future cardiometabolic risks and prepregnancy obesity in subsequent pregnancies.

What's causing the weight gain?

Pregnancy weight gain can arise from both intrinsic and extrinsic factors. Let’s explore these in a bit more detail to better understand what’s causing the weight gain.


Body composition

The average weight of a baby is 7 or 8 pounds (3 to 3.6 kilograms), but that only accounts for some of the weight gain during pregnancy. Here's a sample breakdown of what else contributes to a woman gaining weight:

  • Larger breasts: 1 to 3 pounds (about 0.5 to 1.4 kilogram)
  • Larger uterus: 2 pounds (about 0.9 kilograms)
  • Placenta: 1 1/2 pounds (about 0.7 kilograms)
  • Amniotic fluid: 2 pounds (about 0.9 kilograms)
  • Increased blood volume: 3 to 4 pounds (about 1.4 to 1.8 kilograms)
  • Increased fluid volume: 2 to 3 pounds (about 0.9 to 1.4 kilograms)
  • Fat stores: 6 to 8 pounds (about 2.7 to 3.6 kilograms)

Caloric intake

Weight gain can happen when your clients’ caloric intake exceeds their energy output. 

During pregnancy, the energy needs increase with each trimester, but it may not be as much as your clients think! The myth of “eating for two” often provides an excuse to go overboard on calories, which can lead to excess weight gain. 

In reality, hardly any additional calories are needed in the first trimester, whereas in the second and third trimesters, an extra 300 calories a day may be sufficient.

Best foods to eat while pregnant

Your client’s diet quality will go a long way in determining the health of both mom and baby. While it’s crucial to consume a healthful diet, some nutrients take precedence during pregnancy. Here are some of the best nutrients and foods to eat while pregnant.


Folate and folic acid

Folate (or folic acid) is a B vitamin that has been shown to help prevent major birth defects of the baby’s brain and spine called neural tube defects.

Experts strongly recommend pregnant women consume 600 micrograms of folic acid each day. This can be achieved through supplementation or dietary sources like fortified foods, dark green and leafy vegetables, citrus fruits, dried beans, peas, and lentils. 



Calcium is a mineral that contributes to the baby’s bones and teeth. 

It’s recommended that women under 18 have 1,300 mg of calcium per day, whereas those over 19 years old consume 1,000 mg per day. This can be achieved through supplementation or dietary sources like dairy products, broccoli, fortified foods, sardines, anchovies, and leafy green vegetables. 


Vitamin D

Vitamin D works with calcium to help build the baby's bones and teeth and helps promote healthy eyesight and skin.

It’s recommended that all women, regardless of pregnancy status, consume 600 IU of vitamin D per day. This can be achieved through supplementation or dietary sources like fortified foods, mushrooms, and fatty fish such as salmon and sardines.



Iron is a mineral that is important during pregnancy, as it helps red blood cells deliver oxygen to the fetus.

Women who are not pregnant need 18 mg of iron per day, whereas pregnant women need 27 mg per day. This increased amount can be achieved through supplementation or dietary sources like lean red meat, poultry, fish, dried beans and peas, iron-fortified cereals, and prune juice.

Foods to avoid while pregnant

Not all foods are fair game during pregnancy, so you should work with your clients to educate them on what foods to limit or avoid. 

Here are some foods to avoid while pregnant. 

  • Raw fish and eggs: While cooked fish can offer many health benefits, your client must avoid fish that are raw and high in mercury since they can have a higher risk of bacteria contamination. Raw eggs can also contain salmonella, which is a harmful bacteria that can adversely affect the baby.
  • Processed junk foods: Foods like pastries, pies, cakes, sugary cereals, and processed meats can increase your client’s risk of excess weight gain, which may lead to gestational diabetes and other pregnancy complications. 
  • Unwashed produce: Unwashed or unpeeled fruits and vegetables may be contaminated with several bacteria and parasites. 
  • Unpasteurized foods: Foods such as raw milk, unpasteurized cheese and eggs, and soft-ripened cheeses might contain harmful bacteria.

Eating out vs. cooking at home

Food should be enjoyable, not a chore. However, this can change during pregnancy thanks to food preparation and cooking methods used.

Cooking at home is the easiest way to control meals since your client can monitor how ingredients are prepared and cooked, as well as the overall nutrition content of the meal. 

However, eating out at a restaurant can be challenging since your client may not know what ingredients were used or how they were prepared. But this isn’t to say that eating out is off the table for 9 months! You can help your clients enjoy eating at restaurants by educating them on how to read and understand nutrition facts on the different menu offerings. This will help them plan and alleviate stress.  

Should your client exercise while pregnant?

If possible, your client should exercise while pregnant. According to the American College of Obstetrics and Gynecology, pregnant women are encouraged to exercise for 30 minutes a day, most days of the week.

Exercise has been positively associated with a healthy pregnancy, as it helps prevent excess weight gain, gestational diabetes, and the potential complications associated with obesity during pregnancy. It can also improve glucose levels, reduce maternal fat storage, and lower fetal adiposity.  

However, exercise may not be suitable for everyone. Certain situations or medical conditions may hinder someone from exercising, so be sure to work with each client to determine the right amount of physical activity for their needs. 

Body image during pregnancy

The body goes through some major changes during pregnancy and it can be hard for your client to not feel frustrated with pregnancy weight gain. Here are some ways you can help encourage your client with body weight during pregnancy. 

  • Ditch the scale at home. The scale may be triggering, so encourage these clients to avoid the scale at home and have them keep a record of weight changes instead. 
  • Remind them that these changes are normal. Weight gain can be hard for some women to grapple with, so gently remind them that these changes are normal, and are beneficial for the baby’s growth and development.
  • Show appreciation for their body. Instead of being negative about weight gain, encourage your clients to appreciate how their body is changing and what it’s doing. After all, growing a human being is no small feat!


Gaining weight during pregnancy is normal; however, excess weight gain can negatively affect the health of both mom and baby. You can help your clients maintain a healthy weight gain by providing a meal plan rich in iron, calcium, vitamin D, and folate, and encouraging physical activity if appropriate. 



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