What Causes Sudden Weight Gain In Pregnancy

Very fast and extreme weight gain (such as 1 kilogram within a week) can be a sign of health problems such as pre-eclampsia. The main symptom of this pregnancy-related condition is high blood pressure, sometimes accompanied by nausea, headaches and dizziness too.

Weight gain in pregnancy is common, especially in the second and third trimesters, but sudden weight gain can also be a sign of health problems. Reasons for this could be high blood pressure or pre-eclampsia. Pre-eclampsia can be recognised by very fast and extreme weight gain (such as 1 kilogram within a week).

It is normal to gain weight during pregnancy. However, you lose the weight soon after the birth of your child. If you start gaining weight too fast (such as 1 kilogram within a week), this can be a sign of health problems such as pre-eclampsia.

What Causes Rapid Weight Gain In Pregnancy

You can gain as little as 0.5 kg during your first trimester, but in the second and third trimesters, you could gain up to 2 kilograms per week in extreme cases. You may also experience rapid weight gain due to water retention in your body. This extra fluid puts pressure on your heart and circulatory system, and causes discomfort such as swollen hands and feet or increased urination.

Some women will gain a lot of weight during pregnancy, but most pregnant women do not. One way to tell if you are gaining too much is your BMI (body mass index). For example, a healthy BMI for someone who is 5’3” tall or less would be between 19.5 and 24.9 kg/m². If your BMI is above 25 you may be at risk for gaining too much weight during pregnancy. If you are overweight or obese before becoming pregnant and gain excessive weight during pregnancy, it can be harmful to both you and baby.

Sudden Weight Gain in Pregnancy Second Trimester

If a woman puts on weight very suddenly, or if she generally gains more than half a kilogram per week, her weight will be monitored by a doctor or midwife. Additional tests and examinations might be needed too.

Very fast and extreme weight gain (such as 1 kilogram within a week) can be a sign of health problems such as pre-eclampsia. The main symptom of this pregnancy-related condition is high blood pressure, sometimes accompanied by nausea, headaches and dizziness too. Pre-eclampsia can be life-threatening for both the mother and her child, and it needs to be treated by a doctor as soon as possible.

Putting on a lot of weight in pregnancy can increase the risk of women developing diabetes in pregnancy (“gestational diabetes”) – or it can be a sign that they have developed it. Gestational diabetes is where blood sugar levels increase in women who didn’t have diabetes before becoming pregnant. Gestational diabetes increases the risk of pre-eclampsia, and can result in the unborn baby putting on a lot of weight. Having a very big and heavy baby can delay the birth and make it more difficult for the woman to give birth to her child naturally (“spontaneously”).

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Does avoiding too much weight gain have any advantages?

Paying special attention to diet and getting more exercise during pregnancy may lower certain health risks. This will depend on several factors, including whether the woman is overweight or has gestational diabetes. Research hasn’t shown any advantages for women who have a normal weight.

But women who are very overweight (BMI of over 30) can lower their risk of gestational diabetes by changing their diet and getting more exercise. Previous studies haven’t shown that this will lower the risk of complications during childbirth or prevent the need for a Cesarean section, though.

Women with gestational diabetes are advised to change their diet in order to lower their blood sugar levels. That can lower the risk of complications during childbirth.

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Dietary changes and exercise during pregnancy

Because carbohydrates increase blood sugar levels, women who are very overweight or have gestational diabetes are usually advised to cut down on carbohydrates (“carbs”) while making sure that they still get enough fiber, and to generally eat a balanced diet otherwise. Other common advice includes eating three not-too-big main meals and two to three smaller meals per day.

The exact dietary changes to be made will depend on things like how much the woman weighs and how much exercise she gets. Getting special advice from a nutritional therapist can help to avoid adverse effects. Pregnant women need to make sure that they get enough calories and important nutrients, which is why they shouldn’t go on a low-calorie diet, for instance.

Doing at least 30 minutes of a strenuous physical activity on about three to four days per week is often enough. Suitable types of exercise include swimming, cycling and brisk walking. Women with a greater risk of preterm birth are usually advised to avoid sports altogether. When in doubt, don’t hesitate to ask a gynecologist.

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How can underweight pregnant women gain enough weight?

If a woman who is underweight becomes pregnant and finds it difficult to put on weight, she can seek advice from her doctor or midwife. Studies suggest that professional dietary advice can help women gain weight and lower the risk of giving birth too early (preterm birth).

Protein supplements have been found to help some underweight women increase their weight. This lowers the risk of their child being born underweight, as well as reducing the risk of having a miscarriage. However, very protein-rich dietary supplements with a protein content of more than 25% don’t appear to help. Research also suggests that these very high-protein products might limit the growth of the baby. So it’s important to make sure you get a balanced mix of nutrients. “More” is not “better” in this case.

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Does watching your weight prevent stretch marks?

There is no clear answer to this question yet. Although there are many claims about what causes stretch marks and what might help, none of them have been confirmed in good-quality research.

Whether or not women get stretch marks not only depends on how much weight they gain in total. Factors like how fast they gain weight can make a difference too. For instance, gaining a lot of weight very suddenly can cause more stretch marks than gaining weight gradually. But it’s not clear whether stretch marks can be prevented by keeping your weight down.

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Losing weight after having a baby

Many mothers find that it takes a while before they reach their pre-pregnancy weight again. For some women, breastfeeding and taking care of a baby are enough to melt away the weight gained during pregnancy: It’s as though they really need this stored up energy to help get through the first few weeks and months of motherhood.

But most women won’t really get close to their pre-pregnancy weight until perhaps six months after giving birth. Women who don’t lose weight, or even gain weight instead, might have a higher risk of health problems. These problems could get worse in other pregnancies.

The best way to lose weight is by combining a change in diet with extra physical exercise. Exercise alone probably won’t do much. Programs to help people change their eating and lifestyle habits are often used to try to lose weight. In the research on these programs, women started weight control efforts a month or two after giving birth, and sometimes later. Immediately after birth, mothers need enough nutrients to breastfeed their child, so it is not a good time for them to try to lose weight.

Too much, or too sudden, weight loss can have disadvantages too. For instance, if you go on a diet that is too strict or too one-sided after having a baby, it could reduce the quantity of your breast milk or the nutrients it contains.

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How do women feel about their weight in pregnancy and afterwards?

Women are constantly surrounded by (nearly always digitally edited) photos of models with supposedly “ideal” bodies. Pregnant women are confronted with these photos too. This makes it difficult for many of them to be happy with their figure, and it can damage their self-image and enjoyment of their body. The media add to the pressure on pregnant women and mothers by focusing a lot of attention on how quickly celebrities return to their pre-pregnancy figures. But women need to gain weight during pregnancy – and they can’t expect to lose it all again within a few weeks after giving birth.

A lot of women see pregnancy as a time to simply enjoy their belly, curves and the baby growing inside their body – and allow themselves some “time off” from worrying about their size. That can be one of the really pleasant parts of being pregnant.

It could only become a problem if you get too far out of your normal weight range and change your eating habits too much. Then it might be harder to get back to your healthier “pre-baby” weight and lifestyle. Women who don’t become very overweight when they are pregnant will probably find it easier to get back to normal afterwards. But you don’t have to be thin to be happy and healthy, and have a healthy baby.

How Much Weight Gain is Normal During Pregnancy in Kg

Women experience many significant physical and emotional changes during pregnancy. Third trimester weight gain is an important part of later pregnancy and is not usually a cause for concern.

Many women will experience rapid weight gain during their third trimester. This is because the fetus typically gains the most weight in this time, according to the Office on Women’s Health (OWH)Trusted Source.

In this article, learn what to expect during the third trimester, when to see a doctor, and some tips on how to gain weight safely during pregnancy.

Average weight gain during the third trimester

Pregnant Woman Belly. Pregnancy Concept. The third or fourth month. Second trimester. Pregnant tummy close up in third trimester
Alona Siniehina/Getty Images

The amount of weight a woman gains during pregnancy depends on several factors, including:

  • their pre-pregnancy body mass index (BMI)
  • the number of gestations
  • physical activity levels
  • nutritional habits

The amount of weight a woman might expect to gain during her pregnancy depends on her pre-pregnancy BMI.

The following table contains pregnancy weight gain recommendations, in pounds (Ib), based on BMI from the Centers for Disease Control and Prevention (CDC)Trusted Source:

BMI before pregnancyWeight gain recommendations for women pregnant with one fetusWeight gain recommendations for women pregnant with twins
<18.528–40 lb50–62 lb
18.5–24.925–35 lb37–54 lb
25–29.915–25 lb31–50 lb
≥3011–20 lb25–42 lb

When to see a doctor

Women who are pregnant should seek immediate medical attention if they experience any of the following symptoms:

If a woman has concerns about third trimester weight gain, it is important that they speak with a doctor.


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The purpose of weight gain

A fetus usually gains the most weight during the third trimester. They will gain an average of 5 lb and grow around 4–6 inches during the third trimester, according to the OWHTrusted Source.

In addition to the weight from the growing fetus, the body also gains weight from:

  • the placenta
  • amniotic fluid
  • breast tissue
  • increased blood supply
  • a larger uterus
  • fat stores for delivery and breastfeeding

Other changes in the third trimester

The following changes and conditions can also occur during the third trimester of pregnancy:

  • shortness of breath
  • heartburn
  • swelling of the feet, ankles, fingers, and face
  • hemorrhoids
  • swollen or tender breasts
  • Braxton–Hicks contractions, which are “false alarms” that are less intense than labor contractions but help the body prepare for it

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Tips to gain weight safely

Women can expect to gain weight during pregnancy. However, in the United States, roughly 50% of all women exceed the recommended ranges for pregnancy weight gain, according to one 2017 studyTrusted Source.

Excessive weight gain during pregnancy can contribute to adverse health effects such as:

Pregnant women can gain weight safely using these following tips:

Work with a healthcare provider

At the start of a pregnancy, a woman’s healthcare provider will determine their weight gain requirements by measuring their BMI.

Healthcare providers will continue to monitor a woman’s weight gain throughout the pregnancy.

Eat a varied diet

Eating a balanced diet will provide vital nutrients, such as carbohydrates, proteins, and fats, that help sustain both the woman and the fetus.

Women can maximize their nutritional intake by consuming a variety of healthful foods and drinks, including:

  • fruits and vegetables
  • whole grains
  • low fat or fat free dairy products
  • proteins, such as poultry, beef, and fish

The Office of Disease Prevention and Health Promotion recommend that women who are pregnant eat 8–12 ounces of seafood each week.

However, certain fish and seafood may contain mercury, which can negatively impact the woman’s health and the fetus’s development.

Safe fish and seafood options include:

  • cod
  • salmon
  • canned tuna
  • herring
  • oysters
  • shrimp
  • trout
  • tilapia
  • catfish

Seafood and fish to avoid during pregnancy due to their mercury content include:

  • bigeye tuna
  • king mackerel
  • marlin
  • orange roughy
  • shark
  • swordfish
  • tilefish

Choosing seafood from sustainable sources can help ensure that it is of good nutritional quality.

Eat several small meals per day

Finishing large meals may present a challenge for pregnant women. Some, for example, may have trouble eating or keeping food down if they have symptoms such as appetite changes, nausea, and vomiting.

Also, toward the end of a pregnancy, the growing fetus and enlarged uterus can crowd the abdomen, leaving less space for the stomach to expand.

In these cases, women may wish to try eating several small meals throughout the day, which means that the body has less to digest in one sitting. This may help minimize uncomfortable digestive issues such as nausea and heartburn.

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