About Pregnancy And Weight Gain – How Much Weight Should I Gain?


Weight gain during pregnancy is something that concerns every woman. We all have that fear of not being able to lose the weight after baby is born.

In hindsight, knowing now that it was going to be a battle trying to lose that weight, I would have been a lot more concerned about my weight gain during my pregnancies. I gained a lot of weight during my first pregnancy but managed to lose most of it before my second pregnancy. Unfortunately I gained even more the second time and I have been overweight since. My weight has fluctuated but my BMI (body mass index) has remained in the overweight range.

So What Is Considered “Normal” For Gaining Weight During Pregnancy?

How much weight should you gain?

It is important to accept that you will put on some weight, but there is no one-size-fits-all recommendation for gaining weight during pregnancy.  How much weight you need to gain depends on:

  • Your pre-pregnancy weight and BMI (body mass index) and
  • Your health

The focus on celebrity pregnancies in which they look fantastic both during their pregnancy and almost immediately after giving birth, does make it hard for a first time mom-to-be to maintain a realistic perspective.

Just remember that every woman is different, our body shapes are very different and pregnancy affects us in different ways.  Some eat healthy diets and still gain too much weight while others eat what they want and still stay naturally slim.

According to the American College of Obstetricians and Gynaecologists Committee Opinion (Number 548, January 2013), the Institute of Medicine Weight Gain Recommendations for Pregnancy is:

For a single baby:

  • If your pre-pregnancy BMI is less than 18.5 (underweight): Gain 28 to 40 pounds(12½ to 18 kg)
  • If your pre-pregnancy BMI is 18.5 to 24.9 (normal): Gain 25 to 35 pounds (11½ to 16 kg)
  • If your pre-pregnancy BMI is 25 to 29.9 (overweight): Gain 15 to 25 pounds (7 to 11½ kg)
  • If your pre-pregnancy BMI is 30 or greater (obese): Gain 11-20 pounds ( 5 to 9 kg)

For twins:

  • If your pre-pregnancy BMI is less than 18.5(underweight): Discuss with your doctor
  • If your pre-pregnancy BMI is 18.5 to 24.9 (normal): Gain 37 to 54 pounds (17 to 25 kg)
  • If your pre-pregnancy BMI is 25 to 29.9 (overweight): Gain 31 to 50 pounds (14 to 23 kg)
  • If your pre-pregnancy BMI is 30 or greater (obese): Gain 25 to 42 pounds (11 to 19 kg)

Use these tables as a general guide to what you should gain during pregnancy.

What is Body Mass Index (BMI)?

Based on your height and weight, the BMI is a simple way of determining if your weight falls within the healthy (normal), underweight, overweight or obese categories (for over 18 years of age).

Healthy Diet

The BMI calculation cannot differentiate between body fat and muscle mass, therefore it has limitations in athletes and bodybuilders in that it can overestimate their BMI. Similarly it can underestimate BMI in the elderly.

The BMI calculation is also not used in pregnant women as it will overestimate their BMI. Therefore the weight gain guideline for pregnancy is based on your pre-pregnancy BMI.

How do you calculate BMI?  BMI is calculated by dividing your weight (kg) by your height squared (m²) or weight (lb) divided by height squared (inches) multiplied by 703.

This BMI calculator will give you both options and is a lot easier than doing the maths.

Pregnancy Weight Gain By Trimester:

This may be an easier way of accessing and monitoring your weight gain during pregnancy.

In general, the average woman should gain about 2 to 4 pounds (1 to 2 kg) during the first three months of pregnancy and 1 pound (500 g) a week during the remaining months.

So for the first trimester, most pregnant women do not gain much weight especially if they are struggling with morning sickness and therefore you can expect to only gain around 2 to 4 lbs. (1 to 2 kg).

Once the second trimester starts, the fetal growth starts in earnest and therefore you can expect your weight gain to be steady throughout the second and third trimesters.

For the second and third trimesters:

If your pre-pregnancy BMI was less than 18.5, you can expect to gain about 1lb. (½ kg)/week.

If your pre-pregnancy BMI was 18.5 to 24.9, you can expect to gain about 14 ounces (400 g)/week.

If your pre-pregnancy BMI was 25 or above, you should gain less than 10½ ounces (300 g)/week.

This converts into gaining around 3 to 4 pounds (about 1.4 to 1.8 kg) a month until delivery.

Gaining weight slowly and steadily is the better option but do not worry if you gain slightly more or slightly less per week or if you have a few spurts when you gain a few pounds suddenly in a short time, as long as it levels off again.

How Many Extra Calories Do You Need During Pregnancy?

To help your baby get the nutrients he or she needs to grow, you need to eat a healthy well balanced diet.

Do you really need to eat for two?  It is no surprise that you do NOT have to eat for two as the average pregnant woman only needs about 300 healthy extra calories per day (for example, half a sandwich and a glass of skim milk).

Looking at the extra calories needed per trimester:

During the first trimester you only need 100 extra calories a day.

In the second trimester you need 350 to 400 extra calories, and in the third, 450 to 500 extra calories.

This is because as your baby grows, so does his or her nutritional requirements.

The average pregnant woman will therefore require about:

  • 1,800 calories per day in the first trimester
  • 2,200 calories per day in the second trimester
  • 2,400 calories per day in the third trimester

Can I Lose Weight During Pregnancy?

Dieting is not recommended during pregnancy. If your doctor considers your weight to be a health risk to you and/or your unborn baby, he/she may want you to lose weight but this will only be on your doctor’s recommendation and under his/her supervision.

Why Is It Important Not To Gain Too Much Or Too Little Weight During Pregnancy?

Putting on too much or too little weight can result in health problems for your unborn baby and for you.

If you are underweight and do not gain the needed weight for your baby’s growth, your baby may be born earlier or smaller (low birth weight) than expected.

If you are overweight, the risk of pregnancy complications such as gestational diabetes, hypertension, having a large baby or having a premature baby or the need for a caesarean section increases.

To help protect your health and the health of your baby, it is important that you gain or maintain the weight recommended by your doctor.

Discuss your weight with your health care provider and determine what’s best for you during your pregnancy and if you are concerned, ask for assistance in managing your weight throughout your pregnancy (such as a dietician).

Where Does All This Extra Weight Go?

Let’s say your baby is born weighing 7 to 8 pounds (3 to 3.6 kg) what happened to the rest of the weight? Let’s have a look:

  • Baby accounts for 7 to 8 pounds (3 to 3.6 kg)
  • Larger breasts account for about 2 pounds (1 kg)
  • Larger uterus accounts for about 2 pounds (1 kg)
  • The placenta accounts for about 1½ pounds (0.7 kg)
  • Amniotic fluid accounts for about 2 pounds (about 1 kilogram)
  • Increased blood volume for about 3 to 4 pounds (about 1.4 to 1.8 kilograms)
  • Increased fluid volume for about 3 to 4 pounds (about 1.4 to 1.8 kilograms) and
  • Fat stores for about 6 to 8 pounds (about 2.7 to 3.6 kilograms)

After childbirth you can expect to lose around 12 pounds (5 kg). Do not stress if you do not lose weight after delivery. It does take time for your body to recover and with a healthy diet, you should see results, depending on how much weight you gained during your pregnancy. It took 9 months to gain this weight so do not expect it to disappear overnight.

I did not lose any weight immediately after either of my deliveries but did start losing weight over the next few weeks (unfortunately not enough!).

For books on eating plans during pregnancy, please visit Mommy To Be on Pinterest.

If you are looking for a pregnancy weight gain chart for yourself, just choose the one with the correct BMI and print it:
Pregnancy weight gain chart (pounds)
Pregnancy weight gain chart (pounds and kilograms)


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