Pregnancy is a period that calls for extra care, a proper diet, and monthly medical checkups. Among the main precautions to ensure a healthy pregnancy and the well-being of both mother and baby, weight gain during pregnancy is one of the main focuses throughout prenatal care. Gaining weight during pregnancy is inevitable, since the woman’s body goes through significant changes to support the baby’s development inside her womb. But controlling this weight gain is essential. Use our weight gain calculator to find out if your body is progressing as expected:
Identify your weight range according to your stage
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Your pre-pregnancy weight: (BMI: )
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Your weight gain range:
How to use the weight gain calculator
The calculation is simple: just fill in the fields with your pre-pregnancy weight, then your current weight, your current gestational age, and also whether your pregnancy is multiples or not. Click the calculate button and your result will appear in the results field below.
Besides indicating whether your weight falls within a healthy index, below or in the obesity range, your body mass index will be provided as well as the estimate of your ideal weight gain.
Below the result you’ll see a chart to show if you are within the expected weight range. The orange dot indicates your current weight, and if it is inside the blue field, you are within the expected weight gain range. If you are above the blue field, you are gaining more weight than recommended, and if you are below, you are gaining less than recommended. If you have any doubts about the result, use the button below to recalculate.
Ideal Weight Gain During Pregnancy
However, weight gain in pregnancy is not only related to diet. It also involves a variety of factors such as genetics, height, age, and even the weight a woman had before becoming pregnant1. The ideal weight gain during pregnancy may vary from woman to woman and will depend on each one’s weight and height and on how much she already weighs before pregnancy. If you are already overweight at the beginning, the recommendation is to gain as little as possible.
Through the BMI calculation, it is possible to determine the appropriate amount of weight a woman should gain throughout the 9 months of pregnancy. This calculation can be done using some tools or even by your obstetrician at the start of prenatal care.
Weight Gain X BMI
- BMI up to 18.5 – If the result of your BMI calculation at the start of pregnancy is up to 18.5, this means you are within a healthy weight range, and the ideal weight gain is between 13 and 18 kg.
- BMI 18.5 to 25 – If your BMI calculation at the start of pregnancy is between 18.5 and 25, the recommended ideal weight gain is 11.5 to 16 kg.
- BMI 25 to 30 – If your BMI at the beginning of pregnancy is between 25 and 30, the ideal weight gain is 7 to 11.5 kg.
- BMI above 30 – If your BMI at the start of pregnancy is above 30, it means you will need to be even more careful with your eating and daily habits since you are already overweight. The ideal weight gain will then be from 5 to 9 kg.
Where extra weight is distributed
Whenever we think about gaining weight and the number of kilos gained throughout pregnancy, the question of where all that weight goes naturally arises, and whether by the end of pregnancy you will be “huge.” But pregnancy weight gain is not the same as the weight we gain when we lose control and don’t have a healthy routine.
Logically, if a baby usually weighs about 3 kg at birth, shouldn’t that be the only weight gained? But a woman’s body, in order to have a healthy pregnancy, adapts to this new phase and undergoes several changes in order to structure itself to support a new life growing inside.
Weight gained during pregnancy is distributed among:
- Weight of the baby;
- Weight of the placenta;
- Weight of the uterus;
- Fluid retention;
- Amniotic fluid;
- Breast enlargement;
- Increased blood volume;
- Increased fat reserves.
There are so many changes that the female body goes through during this period2, and so many demands and overloads, that the body needs to be stronger and better prepared to endure the 9 months of pregnancy.
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It’s well known that pregnancy weight gain is a nightmare for many women, most of whom are concerned about gaining too much. Excessive weight gain is a common concern. Sometimes the fear generated around this factor during pregnancy may be crucial for a woman’s body acceptance and many other issues.
According to medicine, ideal weight gain for a pregnant woman is proportionally distributed based on the development of the organs that are growing at this stage. In other words, all the changes pregnancy brings — both to her body and to the new being growing within her. The ideal weight can be distributed as follows:
The baby > About 3.1 kg comes from the baby’s weight. Sometimes much more; there are many pregnancies in which the baby weighs over 4 kg, and a baby weighing as little as 2.5 kg can also be completely healthy. In fact, a baby’s health isn’t determined by weight alone. So, if your baby is theoretically not at an ideal weight, don’t worry. During pregnancy, your baby’s weight gain is considered to assess the mother’s health. So, a woman who has a child weighing 3 kg and gains 20 kg during pregnancy would have an excess of 17 kg without accounting for the other factors involved.
The placenta > It weighs about 1.1 kg! That’s big, isn’t it? But it’s vital so that the baby gets proper nutrition and oxygen. A healthy placenta is fundamental!
The amount of amniotic fluid > Amniotic fluid in pregnancy weighs about 1.2 kg! This is because the weight is proportional to the volume in liters. In this case, 1,200 ml equals 1.2 kg. If you have extra fluid, you will weigh more. Normally, without excess fluid, it is up to 1,300 ml.
The uterus > As the uterus grows, obviously there is additional weight gain during pregnancy. Since it’s muscle, the uterus can get quite heavy! It can reach up to 1.6 kg of a pregnant woman’s weight.
Fat reserve (adipose tissue): Everyone has a minimum fat reserve under the skin. For some women the fat may be minimal, but for others it can get up to 4 kg! That’s why you should consider your body type, but it’s perfectly normal for a pregnant woman to have this amount of adipose tissue under her skin!
Blood > The woman’s blood volume increases considerably! That’s so both the mother and baby have good circulation, the blood gets more fluid. There’s about 30% more water in the blood produced by the mother, which is about 1.7 kg of extra weight gained in pregnancy. This also explains fluid retention and swelling!
Body fluids > Approximately 1.1 kg of pregnancy weight gain comes solely from hormonal fluids in the body. Extracellular fluids from the placenta hormones help retain fluids because they increase sodium retention. So watch out for your blood pressure and swelling!
What is the ideal weight gain during pregnancy?
About 14.5 kg! Slightly more than the 11–12 kg some doctors say. However, weight gain during pregnancy varies for every woman. This is a rational estimate from medicine, but each woman’s body type will certainly be taken into account, as well as, of course, the baby’s and father’s body types. Although the baby’s size will influence weight gain, it isn’t the biggest factor. Some women can gain very little weight throughout pregnancy.
That was my experience. During my first pregnancy I gained a reasonable amount, 12 kg with a baby of 2.93 kg. In the second, I gained about 7 kg with a 3.8 kg baby. In my third pregnancy, I gained 5 kg with a 3.45 kg baby. What caused little weight gain in the last two pregnancies was my metabolism, which for some women may slow down significantly, causing excessive weight gain. In my case, acceleration due to the presence of HCG, meant little weight gain for me, but good weight for the babies. As my obstetrician said, I’m a freak of nature: I stay skinny during pregnancy and gain weight afterwards (what can you do?)
Some doctors are overly alarmist about weight gain, but forget to consider that every body is unique, and standards shouldn’t become rules. Of course, healthy weight gain is essential, which is why a good (and healthy) diet should be adopted even before conceiving3. But many factors must be taken into account to determine overweight and pregnancy risks. Talk openly with your obstetrician and enjoy your pregnancy without worrying too much about weight gain. If your baby is healthy and so are you, the weight can be lost after pregnancy with breastfeeding, diet, and exercise.
