What to Do About Weight Loss During Pregnancy

Common Reasons, Concerns, and Special Considerations

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Morning sickness, healthier eating styles, and baby needs may all be reasons for weight loss, especially in the first trimester of pregnancy. A small amount of weight loss may also be indicated for women who are overweight or obese when pregnant for the health and wellbeing of mom and baby. Therefore, if you lose a few pounds early on, you probably shouldn't be alarmed.

It's very important though, to make sure you are getting adequate calories and nutrients to support the health of yourself and the baby. And it is never wise to follow a strict diet or drastically cut calories or food groups. Sometimes losing weight can be problematic and will need medical attention. Make sure you are staying up-to-date with your medical appointments and alerting your physician when anything seems out of the ordinary.

Why am I Losing Weight?

It might seem like a shock to be losing weight during your first trimester of pregnancy, but it can be common, especially in women experiencing morning sickness (which accounts for about 70-80 percent of pregnancies). Occasional morning sickness is not something to be concerned about, especially in the first trimester of pregnancy.

Usually, these symptoms improve, however, sometimes morning sickness can escalate to a more serious condition known as hyperemesis gravidarium (HG). Dr. Chris Han, a physician at the Center for Fetal Medicine and Women's Ultrasound, says "A patient is felt to have HG if she has persistent vomiting accompanied by weight loss exceeding 5 percent of the pre-pregnancy body weight, along with evidence of ketones in their urine." For example, a woman who starts out her pregnancy weighing 140lbs would lose about 7 pounds.

Hyperemesis gravidarum

According to the American Pregnancy Association, "Recent studies show that at least 60,000 cases of extreme morning sickness called hyperemesis gravidarum (HG) are reported by those who are treated in a hospital but the numbers are expected to be much higher than this since many women are treated at home or by outpatient care with their health care provider."

Hyperemesis gravidarum is characterized by severe nausea and vomiting, which can result in severe dehydration and inability to keep food down. Thus, there is a potential to lose weight if you experience this condition.

HG usually appears in weeks 4 to 6 of pregnancy and can peak around 9 to 13 weeks. Most women receive relief around weeks 14-20, however, some women require care throughout their entire pregnancy. Hyperemesis can be treated outside the hospital, but in severe cases, hospitalization may be necessary.

There is no way to prevent this condition, but there are many ways to treat it. Medical interventions may include medications (which will be done at the discretion of your doctor), as well as infusions of intravenous fluids to replace lost fluid and electrolytes. In extreme cases, nutritional support is necessary and may require a surgical procedure. Additionally, some alternative therapies may be recommended. Some examples of these are bed rest, herbal treatments, and acupressure.

Other Medical Issues That Can Cause Weight Loss

Unintentional weight loss, especially sudden weight loss, is a concern and should be evaluated by a medical doctor as soon as possible. Dr. Han, says, "Some causes of weight loss during pregnancy include: uncontrolled overactive thyroid, undiagnosed diabetes, gastrointestinal diseases, cancers, psychiatric disorders, endocrine imbalance, neurologic abnormalities, infections, substance abuse, autoimmune disorders, and other chronic diseases."

Han also says, "The most important intervention for a woman who is losing weight in pregnancy is to identify and treat the underlying reason for the inadequate weight gain."

How Much Weight Loss is Too Much?

Unless recommended by your physician, in general, weight loss is not recommended during pregnancy. Dr. Han states, "Some studies have shown that weight gain below the recommended limits may provide some benefit for women with higher body mass index (BMI) > 30 kg/m2 before pregnancy, but may increase the risk for small babies in women with normal or low BMI."

The current recommendations from the National Academy of Medicine are to adjust total weight gain based on pre-pregnancy body mass index:

  • BMI <18.5 kg/m2 should aim for 28-40 pounds
  • BMI 18.5-24.9 kg/m2 should aim for 25-35 pounds
  • BMI 25-29.9 kg/m2 should aim for 15-25 pounds
  • BMI > 30 kg/m2 should aim for 11-20 pounds.

Can losing weight during pregnancy be harmful?

Losing a very small amount of weight may be okay at the beginning of pregnancy, however, "losing weight during pregnancy has been associated with increased risk of decreased birth weight and preterm delivery," says Han. According to the Center for Disease control, preterm birth occurs when a baby is born too early before 37 weeks of pregnancy have been completed. Babies who have low body weight at birth and are pre-term may be susceptible to other health conditions or abnormalities because their bodies have not had the ability to develop fully. Your physician should work closely with you to monitor your weight so that complications can be prevented and remedies can be determined.

How Can I Prevent Weight Loss?

Eating nutrient dense, small frequent meals, can help to meet caloric needs, reduce nausea, and prevent weight loss. When you are not feeling well it can be difficult to meal prep and plan on your own. Therefore, if you are having difficulty and are unable to gain enough weight or you continue to lose weight, Dr. Han suggests, "Meeting with a dietitian for guidance." A dietitian can provide individualized meal plans based on your nutrient and calorie needs and preferences.

In addition, treating the underlying condition, by starting appropriate therapies, "Such as anti-nausea, anti-depression or anti-thyroid medication, may be necessary," states Han. She also says, "Monitoring weight gain trajectory at routine prenatal visits is important, although I never recommend weighing daily at home, due to normal day-to-day fluctuations."

Are There Any Special Nutritional Needs for Women Who Lose Weight During Pregnancy?

Most women need to increase their calorie needs by 340-450 calories per day in the second and third trimester for adequate weight gain and nutrition. Dr. Han says, "The breakdown of nutritional content should be 1.1 g/kg/day of protein and 175g/day of carbohydrates (in the form of healthy fruits, vegetables, whole grains), and a healthy amount of fat. Water or fluid consumption should be approximately 76 fluid ounces per day, in addition to water content in consumed food. Water and electrolyte replacement is particularly important in women who are experiencing nausea."

For example, for a woman weighing 150 pounds or (68.1kg), she would need to ingest a total minimum of 75 grams of protein per day. To understand quantities of protein, one ounce of meat or fish contains about 7 grams of protein. Therefore one three-ounce (size of the palm of your hand) portion of fish or chicken contains about 21 grams of protein. Other sources of protein include nuts, seeds, legumes, eggs, dairy, cheese, and whole grains.

Understanding portions and nutritional needs can be complex and most women, particularly those with other medical needs, will benefit from seeing a dietitian to help assist them in this process. Dr. Han says, "Nutritional recommendations should always be individualized and take into consideration, physical activity, age, weight, and health conditions." Dietitians are a wonderful resource for providing individualized nutrition therapy.

A Word from Verywell

Weight loss during early pregnancy can be common, but in general, is not recommended for normal weight women. Unintentional weight loss and inability to gain weight requires a medical evaluation. If your weight loss is being caused by an underlying condition, your physician can treat it to prevent future weight loss and protect the health of yourself and your baby. In addition, evaluation by a dietitian can ensure nutritional adequacy through individualized meal planning.

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Article Sources

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  • American Pregnancy Association. Hyperemesis gravidarum: signs, symptoms, and treatment. https://americanpregnancy.org/pregnancy-complications/hyperemesis-gravidarum/

  • Center for Disease Control and Prevention. Preterm birth.

  • Fejzo, M, et. al. Symptoms and Pregnancy Outcomes Associated with Extreme Weight Loss among Women with Hyperemesis Gravidarum. J Womens Health (Larchmt). 2009 Dec; 18(12): 1981–1987. doi: 10.1089/jwh.2009.1431