Scriptures and the Church teach us that a new pregnancy is a gift from God and the fruit of a holy and blessed marriage. Pregnancy is a time of wonder filled with joyful moments like the sound of your baby’s heartbeat, feeling the first kick, and ultimately meeting and snuggling your newborn on delivery day. But pregnancy can come with lots of questions and lots of anxiety. A top question many women have is: how much weight should I gain in pregnancy?

This is a great question because knowledge about pregnancy weight gain is power over anxiety about weight gain. It is also a great question because, in the United States, half of all women gain more than the recommended amount of weight during pregnancy. To figure out your weight gain target, start by calculating your body mass index (BMI) using an online calculator. This number considers your weight and height. Use your pre-pregnancy weight and height. You will then fall into one of four categories:

  • Underweight BMI <18.5
  • Normal weight BMI 18.5-25
  • Overweight BMI 25-40
  • Obese BMI >30

Each category has a target pregnancy weight gain, as suggested by the Institute of Medicine:

  • Underweight (BMI <18.5) 28-40 lbs.
  • Normal weight (BMI 18.5-25) 25-35 lbs.
  • Overweight (BMI 25-40) 15-25 lbs.
  • Obese (BMI >30) 11-20 lbs.

However, BMI is not a perfect calculation. It does not do a great job of considering lean tissue versus fat tissue. So, women who are more muscular or have bigger bones will have a larger BMI but not necessarily more fat tissue. Additionally, pregnancy weight gain targets are different around the world with some countries recommending 18-33 pounds weight gain for normal-weight women. 

Pregnancy weight gain is not a linear trajectory. Some women will not gain weight in the first trimester due to nausea, vomiting, and food aversions. Some will even lose weight in the first trimester if morning sickness is severe. You may feel like you gain lots of weight and feel puffy in the first trimester. This is because your body is in an anabolic state to build up energy reserves, and your body is working to grow a placenta. A gain of three to seven pounds in the first trimester is normal for most women. Some women may suddenly gain several pounds in a week at the end of pregnancy. In the last two trimesters, the body switches to a catabolic state, where it gives as many nutrients as it can to the rapidly growing baby. Many women feel leaner as their body uses up their fat stores for the growing baby. It is not often that women gain too much weight in one week, but if you gain more than four pounds in one week and you also have swelling or water retention, call your obstetrician to rule out preeclampsia or high blood sugar.

In pregnancy, women gain weight for many reasons with the top reason being they are growing another human. Women are also growing a brand-new organ, the placenta. Another change is that breast tissue modifies so that it can begin making breast milk. With all these changes come several pounds of extra fluid circulating through the body to support mom and baby. Women’s bodies will also accumulate fat to help support them during the post-partum period.

There are some risks if women gain too little or too much weight during pregnancy. If women gain too little, their infants could be at risk for low birth weight. If women gain too much, their infants could be at risk for high birth weight, neonatal adiposity, and childhood obesity. This could all lead to later in life metabolic dysfunction. Women who gain too much weight are at risk for gestational diabetes, preeclampsia, and delivery complications.

Some women may be starting out their pregnancy journey with an obese BMI. A study of 120,000 obese pregnant women found that the most favorable outcomes for mom and baby occurred when these women gained less than the Institute of Medicine’s recommended target of 11-20 pounds. These moms had a lower risk of preeclampsia, c-section delivery, and lower chances of a large for gestational age (LGA) infant. At the conclusion of the study, the researchers recommended new weight gain targets:

  • BMI >35 0-9 lbs.
  • BMI >40 lose up to 9 lbs.

This information may still create a bit of anxiety about pregnancy weight gain, but remember 1 Corinthians 10:31 says, “So whether you eat or drink, or whatever you do, do everything for the glory of God.” Your eating and weight gain in pregnancy glorifies God because you are cooperating in His creation of a new life. It is best for all pregnant women to strive to consume high-quality, nutrient-dense, low glycemic index foods while also moving their bodies every day in a way that feels good. If you would like specific dietary advice, please seek out one of the MyCatholicDoctor nutrition professionals or advice from your local obstetrician. For more information, check out the book Real Food for Pregnancy by Lilly Nichols for recipes and advice on eating well during pregnancy. Additionally, if you live in North Carolina and are seeking advice for achieving pregnancy and pursuing healthy habits in the new year, please schedule an appointment with me, as I am eager to help you achieve your conception goals and put your best foot forward into the new year! 

Author: Megan Blum, Physician Assistant and Fertility Provider with MyCatholicDoctor

Editor: Samantha Wright, Director of Education and Online Resources with MyCatholicDoctor

About Megan: PA Megan Blum is a physician assistant with a special interest in providing restorative reproductive care to women of all ages. She has special training in FEMM and Marquette Method and is a medical consultant for both models of women’s healthcare. She became a medical provider to help provide access to fertility-awareness-based medicine to all who seek it. She believes in finding the root cause of women’s health and endocrine issues to restore women’s bodies to optimum health.

Megan E. Blum, PA-C


Nichols, Lilly. (2018). Real Food for Pregnancy: The Science and Wisdom of Optimal Prenatal Nutrition. Lily Nichols.

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