Is It Normal to Lose Weight During Pregnancy?

Losing weight during pregnancy is a topic that causes concern for many expectant mothers. While minor weight fluctuations can occur, significant or intentional weight loss during pregnancy is generally not considered normal or safe, with a potential exception in the very early stages. Adequate nutrition and appropriate weight gain are crucial for your baby’s healthy development. If you’re dieting or losing weight, you might miss out on essential calories and nutrients vital for a healthy pregnancy. This article explores the nuances of weight changes during pregnancy, explaining when minor loss might occur, why deliberate weight loss is risky, and offering guidance on healthy weight management.

Why Might Weight Loss Happen in Early Pregnancy?

It can be normal to experience some weight loss during the first trimester. Several factors can contribute to this:

Morning Sickness

Nausea and vomiting, commonly known as morning sickness, are frequent in early pregnancy. This can reduce your appetite and lead to calorie loss, sometimes resulting in a slight decrease in weight. Usually, this is temporary, and your baby still receives the necessary nutrients.

Pre-existing Fat Reserves

Women who are overweight or obese before pregnancy have extra calorie reserves stored as fat. In the initial stages, as the baby grows, it’s sometimes possible to maintain or even lose a small amount of weight without harm, as the body utilizes these reserves.

Lifestyle Improvements

If you’ve adopted healthier eating habits or started a safe exercise routine upon discovering you’re pregnant, you might initially lose a little weight.

In most instances, this early weight loss is not a cause for alarm. However, if you experience significant weight loss or suspect you might have hyperemesis gravidarum (severe morning sickness), it’s essential to contact your healthcare provider immediately.

Is Losing Weight During Pregnancy Safe?

Outside of the specific circumstances in early pregnancy mentioned above, losing weight while pregnant is generally not safe. Actively trying to lose weight or experiencing unexplained weight loss later in pregnancy is not compatible with supporting a growing baby.

Losing weight can deprive both you and your baby of vital nutrients needed for healthy development. While being overweight or obese carries certain risks during pregnancy, attempting to lose weight during this time introduces different risks, including having a baby who is small for gestational age (SGA) or being born prematurely.

Pregnancy Weight Gain Recommendations for Overweight or Obese Individuals

More than half of pregnant women in some populations start their pregnancy overweight or obese. Your weight category is determined by your pre-pregnancy Body Mass Index (BMI):

• Overweight: BMI between 25 and 29.9
• Obese: BMI of 30 or greater

The amount of weight you should aim to gain depends on your starting BMI:

• BMI 25 to 29.9 (Overweight): Recommended gain is 15 to 25 pounds total, roughly 2 to 3 pounds per month in the second and third trimesters.
• BMI 30 or higher (Obese): Recommended gain is 11 to 20 pounds total.

While intentionally losing weight is unsafe, if you are overweight or obese, your healthcare provider might advise that gaining less weight than the standard guidelines recommend could be safe and potentially beneficial, provided your health and the baby’s growth are closely monitored. Research on Institute of Medicine (IOM) guidelines suggests some overweight or obese women who gained less than recommended amounts (e.g., 6 to 14 pounds) had positive outcomes. Always discuss your individual weight gain goals with your provider.

Why Dieting During Pregnancy Is Not Advised

Pregnancy is not the time for weight-loss diets, regardless of your starting weight. Restricting food intake can be hazardous. You and your developing baby require sufficient calories and a wide range of nutrients.

Avoid carbohydrate-restrictive diets like Keto or Atkins. Your baby needs carbohydrates for growth, and the ketosis these diets induce can potentially harm a developing fetus.

Healthy Ways to Manage Weight Gain During Pregnancy

Focus on achieving a healthy weight gain within your recommended range, rather than losing weight. You can manage your weight effectively by:

• Eating balanced meals and choosing healthy snacks.
• Staying well-hydrated, aiming for about ten 8-ounce glasses of water daily.
• Prioritizing complex carbohydrates (beans, fruits, vegetables, whole grains) over simple carbs (white bread, white rice, white pasta).
• Regularly monitoring your weight with your healthcare provider to ensure you’re on the right track.
• Engaging in regular, pregnancy-safe exercise as approved by your provider.

Pregnant woman sitting comfortably on a park bench using her smartphone, possibly researching healthy pregnancy weight management.

When to Be Concerned About Weight Loss During Pregnancy

Losing weight during the second or third trimester could indicate an underlying issue. While it might occasionally be due to harmless factors like shedding retained water, any weight loss during this period warrants discussion with your healthcare provider.

Your provider will assess your diet, activity levels, and ask about symptoms like nausea, heartburn, bloating, or constipation, which can affect appetite. They may also screen for conditions like depression or check for fetal growth restriction.

It’s crucial to inform your provider immediately if you experience sudden, dramatic weight loss, such as losing five pounds or more within a week.

Conclusion

While it can be normal to lose a small amount of weight in the first trimester due to factors like morning sickness or positive lifestyle changes, intentionally losing weight or experiencing significant weight loss later in pregnancy is generally not safe. Focusing on adequate nutrition and appropriate weight gain, as recommended by your healthcare provider based on your individual circumstances and pre-pregnancy BMI, is essential for a healthy pregnancy outcome. Always communicate any concerns about your weight or eating habits with your doctor or midwife to ensure the well-being of both you and your baby.

References

ACOG. 2021. Nutrition during pregnancy. American College of Obstetricians and Gynecologists. https://www.acog.org/womens-health/faqs/nutrition-during-pregnancy [Accessed August 2021]

ACOG. 2021. Obesity and pregnancy. American College of Obstetricians and Gynecologists. https://www.acog.org/womens-health/faqs/obesity-and-pregnancy [Accessed August 2021]

ACOG. 2020. Weight gain during pregnancy. American College of Obstetricians and Gynecologists. https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2013/01/weight-gain-during-pregnancy [Accessed August 2020]

IOM. 2009. Weight gain during pregnancy: Reexamining the guidelines. The National Academies Press, Washington D.C. https://www.ncbi.nlm.nih.gov/books/NBK32813/ [Accessed August 2021]

Kapadia MZ et al. 2015. Weight loss instead of weight gain within the guidelines in obese women during pregnancy: A systematic review and meta-analyses of maternal and infant outcomes. PLoS One 10(7): e0132650 https://pubmed.ncbi.nlm.nih.gov/26196130/ [Accessed August 2021]

March of Dimes. 2020. Being overweight during pregnancy. https://www.marchofdimes.org/pregnancy/being-overweight-during-pregnancy.aspx [Accessed August 2021]

Rasmussen KM et al. 2010. Recommendations for weight gain during pregnancy in the context of the obesity epidemic. Obstetrics & Gynecology 116(5): 1191-1195. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4288953/ [Accessed August 2020]

Robillard PY et al 2018. Relationship between pre-pregnancy maternal BMI and optimal weight gain in singleton pregnancies. Heliyon 4(5) E00615. https://www.cell.com/heliyon/fulltext/S2405-8440(18)30300-1 [Accessed August 2021]

Siega-Riz AM et al. 2009. A systematic review of outcomes of maternal weight gain according to the Institute of Medicine recommendations: birthweight, fetal growth, and postpartum weight retention. American Journal of Obstetrics and Gynecology 201:339. E1-14. https://pubmed.ncbi.nlm.nih.gov/19788965/