I’m Pregnant But Not Gaining Weight — Is That Normal?

There is no set standard for weight gain during pregnancy — this depends on the mom’s pre-pregnancy BMI, number of babies, and any medical conditions present. No weight gain during the first trimester may be average. In general, moms are expected to gain 1 pound per week from the second trimester onwards. Morning sickness, loss of appetite, and medical conditions are some reasons why moms might not gain any weight. Consequences include premature delivery, a small or malnourished baby, frequent infections for the baby, and developmental delays. Moms should eat healthily, drink enough water, and be proactive with their diet to gain enough weight.

Many first-time moms-to-be may be very conscious of their pregnancy journey and with good reason!

We want to ensure a safe delivery and a healthy baby (or babies).

One common concern is weight gain — what is too much or too little? But sometimes, a mother might find herself with no weight gain at all. Is this normal?

Average weight gain in pregnancy

There is no set standard for how much weight gain is appropriate for all moms.

The expected weight gain depends on how much you weighed before your pregnancy started. This is specifically called your pre-pregnancy body mass index (BMI).

The Institute of Medicine (US) and the National Research Council (US) have released guidelines for the average increase in weight throughout pregnancy, depending on the mother’s BMI.

The trend is as follows: the higher the BMI, the lower the weight gain needed.

Pre-pregnancy BMI (in kg/m2)Average weight gain
< 18.5 (underweight)27.5 – 39.5 lbs (12.5 – 18 kg)
18.5 – 24.9 (healthy weight)25.5 – 35 lbs (11.5 – 16 kg)
25 – 29.9 (overweight)15.5 – 25.5 lbs (7 – 11.5 kg)
≥ 30 (obese)11 – 20 lbs (5 – 9 kg)

This table is for mothers who have a healthy weight (normal BMI), have only one baby in their womb, and do not have any medical complications during pregnancy.

Moms who are overweight, underweight, or have multiple pregnancies might need to consult with their healthcare provider to determine how much weight they should gain throughout pregnancy.

The first trimester (1-3 months)

Surprisingly, not all moms are expected to gain weight during the first three months of their pregnancy.

It’s actually normal not to gain weight. For moms who do gain weight, it can go as high as 5 pounds (or 2 kilograms) for the whole first trimester.

During this period, moms don’t need to worry about “eating for two.”

The second and third trimesters (4-9 months)

According to the American College of Obstetricians and Gynecologists, starting the second trimester, some weight gain is expected.

For the second trimester, moms will need at least 340 calories daily. This increases to 450 calories per day during the third trimester.

On average, they will gain 1 pound every week during these two stages.

Reasons why pregnant women might not be gaining weight

Many mothers worry about not gaining weight, especially during the first trimester. There are several reasons why this happens:

1. Morning sickness

A woman is covering her mouth as she is experiencing morning sickness during her early pregnancy

One significant factor is morning sickness: occasional episodes of vomiting will make it challenging to keep food in the stomach for nutrient absorption.

Some moms have morning sickness so severe that it develops into a medical condition that may need hospitalization — hyperemesis gravidarum.

2. Loss of appetite

Pregnancy leads to changes in hormone levels in the body. This affects each mom uniquely.

For example, while others may have food cravings, some might not have any appetite at all.

Also, because of frequent nausea and vomiting during the first few months of pregnancy, moms might also not want to eat much.

3. Fast metabolism

Very few women are blessed with a fast metabolism — this makes it difficult for them to gain weight.

While this is an advantage in their pre-pregnancy years, it may cause worry during pregnancy itself.

4. Medical conditions

Having certain medical conditions before or during pregnancy can affect weight gain.

Talk with your ob-gyn to find out more about this and to have you and your baby screened. 

Consequences of too little weight gain in pregnancy

As much as 21% of mothers do not gain enough weight for pregnancy. Unfortunately, this directly affects the baby’s growth and development.

Most moms who gain too little weight have babies who are:

  1. Premature
  2. Small for age (low birth weight)
  3. Developmentally delayed
  4. More prone to infections or other illnesses

To-do’s to gain enough weight during pregnancy

Whether you’re steadily gaining weight now or struggling to get a few extra pounds, there are some ways to help increase your weight.

1. Eat healthy

A pregnant woman is eating an apple after doing some light excersises on a yoga mat

This is a simple but important rule. A healthy and balanced diet is more important and impactful than taking vitamins and pregnancy supplements.

With that being said, it’s still essential that you take your daily prenatal vitamins and supplements, especially when these are advised by your healthcare provider.

Stock up on fruits and vegetables, in particular.

Sources of healthy fats are essential as well — eat more fatty fish (thoroughly cooked!) and nuts.

2. Choose water

Pregnancy cravings are hard to battle, but every now and then, moms-to-be have to watch what they take in — including drinks.

Prioritize drinking water above sodas and sugary drinks.

Having enough water will keep you (and your baby) from becoming dehydrated.

3. Don’t forget breakfast

Pregnant women, at some point, are prone to nausea and vomiting.

Having an empty stomach for most of the morning will only further trigger the vomiting episodes. Eat vegetables and fruits (like bananas), yogurt, or wholegrain foods.

4. Be proactive with your eating habits

Stimulate your appetite every morning by eating a piece of bread or a healthy biscuit within the first 15 minutes of waking up.

If you’ve developed any dislike for certain foods or smells, then keep your distance and avoid them as much as possible.

Pregnant women are also encouraged to have healthy snacks in between meals.


Is it okay not to gain weight during pregnancy if you’re overweight?

Some experts say that, in general, women with a BMI of at least 40 may not need to gain any weight.

It’s best to consult with your ob-gyn because the recommended weight gain may differ per person, depending on the presence of other medical conditions.

Is it okay to lose weight during pregnancy?

Losing weight, intentionally or not, is a no-no during pregnancy.

Even if you have enough nutrient stores in your body, this will not be enough for both you and your baby if you start to lose weight while pregnant.


While it may be alright not to gain weight during the first 3 months of pregnancy, moms should start gaining weight during the second and third trimesters.

Morning sickness, loss of appetite, and medical conditions are important causes of lack of weight gain.

Have regular prenatal checkups with your ob-gyn to find out if you’re gaining weight adequately and how to ensure you get enough of those pounds.

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Sarah is a healthcare writer, motivated by her love of reading books while growing up. She took up human biology and further studies in medicine, in order to fulfill her passion for helping kids. While she isn't a biological mother yet, she has taken two young dogs, named Indy and Obi-Wan, under her wing. She would love to someday travel the world and meet kids from different cultural backgrounds.

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