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The important thing you need to know about pregnancy weight gain

Finding out that you are pregnant comes with a tidal wave of emotions and questions, not the least of which involve your body and all the (wonderful/annoying/amazing/scary) ways it will change. If you’re wondering about pregnancy weight gain, you are certainly not alone.


As women we are often bombarded with information about what our bodies should look like—it’s seriously everywhere. It can be really challenging when we become pregnant. On the one hand, we want to help our babies have the best start to life. We also want our own bodies to be healthy and strong during the awesome-yet-totally-intense work of growing a human.

But we also have to balance that with the societal messages we’ve absorbed about how we should look, along with how we want to feel in and about our own bodies.

It’s not easy.

Let’s start with the guidelines. The American College of Obstetricians and Gynecologists (ACOG) and the American College of Nurse-Midwives recommend that women gain anywhere from 11 to 40 pounds during their pregnancies, depending on their pre-pregnancy BMI (Body Mass Index).

If you’re not sure of your BMI, you can calculate it here.

According to ACOG if your pre-pregnancy BMI is:

  • 18.5 or less, you should gain 28 to 40 pounds
  • 18.5-24.9 you should gain 25 to 35 pounds
  • 25 to 29.9 you should gain 15 to 25 pounds
  • 30 or greater you should gain 11 to 20 pounds

No, you are not about to give birth to a 40 pound baby! In fact, the baby only accounts for some of the weight you’ll gain.

The makeup of pregnancy weight gain:

  • Breasts: 1 to 3 pounds
  • Placenta: 1 to 2 pounds
  • Uterus: 2 pounds
  • Blood 3 to 4 pounds
  • Amniotic fluid: 2 pounds
  • Body fluid: 2 to 3 pounds
  • Fat: 6 to 8 pounds
  • Baby: 7 1/2 pounds

In a recent study, the Centers for Disease Control (CDC) found that only about one third of women in the United States were gaining weight within those parameters.

Twenty percent of women were gaining less than the recommended amount. Gaining too little weight during pregnancy is significant because it can lead babies to be born with low birth weight, which can cause problems for the baby like diabetes, high blood pressure, and believe it or not, obesity later in life.

Almost half of women are gaining more than the recommended amount of weight. Excessive weight gain during pregnancy can put a woman at risk for gestational diabetes and a more difficult pregnancy and birth, and can increase the chance that her baby will be overweight later in life.

This is all pretty overwhelming, and quite frankly, very stressful.

A few things to keep in mind—

Researchers are starting to question the usefulness of BMIs as a marker for health, as people’s body sizes and types vary so much. For example, Alexandra Sifferlin writes in Time Magazine that “BMI...doesn’t tease apart different types of fat, each of which can have different metabolic effects on health.”

Scientists are looking into other methods of assessing weight, but in the meantime, "doctors [should] combine BMI with a comprehensive evaluation of their patients’ medical history and lifestyle habits to get a meaningful, if not yet perfectly precise picture of their weight-related health. It is possible that as ur knowledge BMI evolves, so to will the pregnancy recommendations.

Another factor is that many women start eating much healthier when they become pregnant. This sudden change in diet can impact the amount of weight gained.

Lastly, there are so many medical conditions that can influence how much weight a woman gains in pregnancy. For example, if a woman has hyperemesis gravidarum, a severe case of nausea and vomiting, she’ll likely lose a fair amount of weight in the beginning of her pregnancy. A woman with a history of an eating disorder may have other unique challenges during her pregnancy.

The important take-home here is that every woman, pregnancy and baby is different. Talk to you midwife or doctor about what your target weight gain should be.

In a world full of pressure to fit the mold and be perfect, remember that you already are perfect for your baby. He loves you just as you are. You’ve got this.

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