Expected Baby Weight Gain In Pregnancy

Know what the normal baby weight gain in pregnancy should be for every woman. We bring you a range of BMI just before pregnancy and the range of weight gain you should expect. Also see the risks and complications that could arise from an abnormal baby weight gain. 

Baby weight gain in pregnancy: what should it be?

For many mothers, the amount of baby weight gain they would experience in pregnancy could be a source of concern. 

It is very important for both mom and baby that a healthy weight is attained and maintained during pregnancy.

In a study published by Dr. R. Gaillard and his colleagues in The International Journal of Obesity, 5908 mothers and their children were followed up from when the mothers were in early pregnancy until the children were 6 years of age. 

They found that higher weight gain in early pregnancy is associated with:

  • More problems in the mother during pregnancy
  • Heart and metabolic problems in the children from early pregnancy into later childhood.  The children have increased tendency to develop hypertension later in life
  • The kids tend to be overweight or obese in later childhood or early adulthood. 
  • Mothers who gain too much weight in pregnancy are at a greater risk of having babies who are born large for their age. 
  • The mothers tend to have more complications in pregnancy like high blood pressure and difficulty with giving birth. 

The same is true for mothers who are underweight during pregnancy.

The Journal of Obstetrics and Gynecology of December 2006 – Volume 108, Issue 6, on page 1448 reported an original research article by a group of doctors.

  • They consistently found a relationship between low maternal weight gain in pregnancy with early pregnancy loss, spontaneous preterm birth (premature babies). 
  • Mothers who gain too little weight in pregnancy are also more likely to have babies who are small for their age.

How Much baby Weight Should I Gain During Pregnancy? 

In the 1930’s, doctors erroneously advise pregnant women to put on no more than 15 pounds or about 7 kg during pregnancy. This led to an increase in children born with low birth weight and poor brain development. 

Over the years, there are piles of evidence to show that a normal baby weight gain in pregnancy for a healthy mother and baby development should be between 25 to 35 pounds or 11 to 16 kg. 

About 3 to 6 pounds is usually gained in the first trimester of pregnancy (the first 3 months) and then another 15 to 25 lbs added in the second and third trimester, at a rate of about 1 pound per week.

This healthy baby weight gain comes from:

  • The weight of the baby itself  - 7 to 8 pounds or 3.2 to 3.6 kg
  • Fat gained as part of normal metabolic, nutritional and protective development in pregnancy – 6 to 8 pounds or 2.7 to 3.6 kg
  • Blood and body fluid increase in the mother – 5 to 7 pounds or 2.3 to 3.2 kg
  • Increased weight or the pregnant uterus  – 2.2 pounds or 1 kg
  • Placenta – 1.5 pounds or 0.7 kg
  • Amniotic fluid in which the baby swims – 2 pounds or 0.9 kg
  • Increased breast size in pregnancy – 1 to 3 pounds or 0.45 to 1.4 kg

Off all the above, what tends to change for most mothers is the amount of fat accumulated due to their diet and lifestyle during pregnancy. 

Whether you are underweight, have normal weight, overweight or obese just before you are pregnant, the following is a guide to the amount of baby weight  you can expect to put on. 

How Much Baby Weight Should I Gain During Pregnancy? 

How much weight to put on during pregnancy?

For many women, it is very confusing to hear that you should not put on too little or too much weight on during pregnancy, yet you should be eating for two!

How can I eat for two and not put on too much baby weight? 

Eating for two refers more to the consciousness that once you are pregnant, you should pay attention to what you eat in terms of choosing healthy safe foods in pregnancy, rather than eating more. 

As part of your first prenatal (also called antenatal) visit, your doctor or healthcare provider would usually discuss with you what to eat in pregnancy as well as your expected baby weight gain in pregnancy for your particular body mass index just before you became pregnant or in the first few weeks of pregnancy. 

Body Mass Index or BMI, if the value that shows what your weight is for your height.  It is calculated by dividing your weight in kilogram by the square of your height in meters (BMI = Weight in kg ÷ Height in m2 ).

A normal BMI is between 18.5 to 24.9

If your BMI is below 18.5, you are considered underweight. If your BMI is between 25 and 29.9, that is categorized as overweight and a BMI above 30 is considered obese. 

The table below shows what your expected weight gain should be depending on your BMI before you became pregnant.  

Range of baby weight gain expected during pregnancy. Photo credit: Alberta Health Services.Range of baby weight gain expected during pregnancy. Photo credit: Alberta Health Services.

There is also an expected range of baby weight gain in pregnancy for twins pregnancy for the different ranges of BMI before pregnancy. 

BMI Before or During Early Pregnancy

18.5  to 24.9

25 to 29.9

30 and above

Expected Baby Weight Gain During TWIN Pregnancy

37 to 54 lbs (16.8 to 24.5 kg)

31 to 50 lbs (14.1 to 22.7 kg)

25 to 42 lbs (11.4 to 19.1 kg)

The expected weight gain during a twin pregnancy for mothers who are underweight - those with BMI below 18.5 is unknown. This is because we don't have enough data to determine this. 

Maintaining A Healthy Weight During Pregnancy

You can attain and maintain a healthy weight in pregnancy by following healthy diet and exercise regimens. Good sleep (7 to 9 hours  of restful sleep), exercise and diet remains the bedrock to achieving and maintaining your health and weight in pregnancy. You can read more on tips to help lose weight in pregnancy if you are overweight in pregnancy or putting on more than the expected baby weight, as well as safe exercises to perform during pregnancy here