Pregnancy Weight Gain: How Much is Normal?

Are the numbers on the scale going up lately? Don’t stress! You’re carrying a baby in your belly, so you’re supposed to be gaining weight. However, putting on more than necessary to isn’t good for mothers or their babies, and neither is losing too much.

Let’s look at weight management strategies for pregnancy, including what weight gain means for your baby’s birth and future development, and the impacts of being overweight or underweight can have on the pregnancy and birth.

Where does the weight gain in pregnancy go?

pregnant woman weight scales

Although the average baby comes into world clocking in at about 7.7 lbs, moms gain more than this during pregnancy. Pregnancy weight gain includes the weight of the placenta (just over 1 lb), the amniotic fluid (around 1.8 lbs), and an increase in breast tissue, uterus, and blood volume (a little over 8.8 lbs combined).

You will also gain weight as your body stores fat to give you the energy you need for breastfeeding. Due to changes in hormone balance, mothers’ bodies also tend to retain more water. All in all, women who began their pregnancy in a healthy weight range are usually expected to gain between 25 to 35 lbs over the course of the pregnancy.

Pregnancy weight gain the healthy way: Check your BMI!

BMI measuring tape note

So, how do you know what’s a healthy weight for you during your pregnancy? Before setting a goal weight, you’ll need to calculate your Body Mass Index (BMI). To find your BMI, divide your weight (in kilograms) by the square of your height (in meters).

For example, imagine a woman who is 5’4” and 125 lbs. That works out to 1.63 m and 56.7 kg.
1.63 x 1.63 = 2.66
56.7 ÷ 2.66 = 21.32
This means her BMI is 21.32 – or effectively, 21.3 – which is in the healthy weight range for her height.

BMI and your ideal weight gain during pregnancy

Weight gain goals

  • BMI <18.5 (underweight): 28 – 40 lbs.
  • BMI 18.5 to 24.9 (healthy weight): 25 – 35 lbs.
  • BMI 25 to 29.9 (overweight): 15 – 25 lbs.
  • BMI 30 and over: 11 – 20 lbs.

The ideal weight gain range depends on the mother’s build before pregnancy, so these numbers are more of a general guide. For example, very healthy athletes may be considered “overweight” due to their high muscle mass.

If you are carrying twins or multiples, you will also need to gain more weight. If your BMI is over 25, consider talking to your doctor about the best way to manage your weight during pregnancy.

How fast should I be gaining weight during pregnancy?

food rusk

The ideal pace of weight gain during pregnancy varies with the mother’s BMI, but in general, those who started their pregnancy in a healthy weight range should aim to gain 2 to 4 pounds during the first three months, and then 1 pound a week for the rest of the pregnancy. However, the pace of weight gain often slows in the final stages of pregnancy, so you may gain less in the last few months.

To break that down more precisely, that means gaining around 4.5 lbs by the time the placenta has finished forming, followed by 11 lbs over the stable period beginning in the second trimester period when morning sickness usually subsides.

This works out to about 1 lb per week over the second and third trimesters. As excess weight can put you at risk of complications, your doctor may recommend adjusting your weight gain goals based on your actual rate of weight gain – particularly towards the end of pregnancy.

When you’re pregnant, the placenta releases a hormone called hPL (human placental lactogen). This hormone makes it to put on weight easier than usual, even if you’re leading a similar lifestyle to before you became pregnant. This is why it’s important you don’t become too much of a couch potato – particularly once you get through the morning sickness of early pregnancy.

What if I gain too much weight during pregnancy?

woman question

Gaining too much weight during pregnancy puts you at risk for the following conditions:


Preeclampsia is a hypertensive complication of pregnancy – meaning it is related to high-blood pressure in the pregnant mom. It is characterized by symptoms of high protein levels in urine, and edema (swelling) of the limbs and face. Most often occurring after week 20, this dangerous high blood acupressure condition affects up to 8% of all pregnancies.

When preeclampsia occurs, it can cause reduced blood flow to the placenta – which is the fetus’ source of nutrition. Effects for the fetus can include pre-term or premature birth, and even stillbirth. This condition can also put the mother at risk of life-threatening outcomes like eclampsia, pulmonary edema, premature separation of the placenta, and stroke.

You can manage your risk of preeclampsia by following your physician’s advice on how to keep your blood pressure in a healthy range. Genetic factors are thought to play a role too, so check whether you have a family history of preeclampsia.

Gestational diabetes

Gestational diabetes is a metabolic disorder that affects pregnant women. It doesn’t necessarily mean that you had diabetes before you became pregnant, or that you will be diabetic after delivering your baby. Rather, as the placenta is releasing pregnancy-related hormones like progesterone, this interferes with the action of insulin (the hormone that regulates blood sugar levels). As a result, your blood sugar remains at a higher level than normal.

Gestational diabetes affects around 2 to 5% of pregnant women, though this number can be as high as 9% for women with other risk factors. Risk factors include being overweight, having a family history of diabetes, and maternal age over 35.

Gestational diabetes puts the fetus risks of birth defects, macrosomia (being too large), low blood acupressure, and even death. Mothers may also be in danger of high blood pressure or preeclampsia, as well as excessive amniotic fluid building up in the uterus.

Screening tests for gestational diabetes are available from the early stages of pregnancy, so if your doctor suspects you may be at risk, they doctor will be able to advice you on how to regulate your blood sugar before and after a meal. In some cases, you may be prescribed insulin shots.

What if I don’t gain enough weight during pregnancy?

pregnant woman

Women who don’t gain enough weight during pregnancy may not pass on enough nutrition to their developing baby. This increases the risk of low birth weight – a condition defined as newborns weighing less than 2500 g, or 5 lbs 8 oz.

Low birth weight is often associated with underdeveloped vital organs, and can result in poor cognitive, motor, and physical development outcomes for the child. Studies also show that low birth weight is even associated with chronic diseases in adulthood, such as diabetes and high blood pressure.

Risks for the pregnant mother also include threatened preterm labor and premature birth. This goes to show how important it is to gain enough weight during pregnancy!

Healthy weight = happier pregnancy

pregnant  woman chatting friend

Being overweight or underweight brings a range of risks for your pregnancy, so it’s best to avoid either! The first step to keeping your pregnancy weight in a health range is to watch your diet. But remember – stress isn’t a healthy weight control method! If you make sure you eat well to get the nutrition you need, avoid consuming too much salt, and weigh yourself regularly, you’ll stay on the right track for a healthy weight during pregnancy.