Is Weight Loss During Pregnancy Safe? Pregnancy Weight Loss Guidelines

Proper weight gain in pregnancy is extremely important for the health of you and your baby. However, some women may find that they lose weight during pregnancy, which can be quite concerning.

If you're experiencing weight loss during pregnancy or wondering if it's healthy to lose weight while pregnant, it's important to understand the causes of weight loss during pregnancy, what safe and healthy weight loss looks like, and when pregnancy weight loss may be a sign of concern. 

Related: ​​Exercise During Pregnancy: The Absolute Dos and Dont’s 

Recommended Weight Gain For Pregnant Women 

Following specific weight guidelines is extremely important for maintaining a healthy pregnancy and lowering your risk of developing conditions like gestational diabetes, preeclampsia,  and delivery complications. 

Once you find out that you are expecting, talk to your healthcare provider about your specific weight gain goals to ensure that you and your growing baby can remain healthy throughout the pregnancy.

How Much Weight Should You Gain During Pregnancy?

While the phrase “eating for two” is commonly thrown out when pregnancy is announced, providers don’t actually recommend literally eating for two. 

In fact, if you fall in a normal weight category (if your body mass index, or BMI, is between 18.5-24.9), the American College of Obstetricians and Gynecologists (ACOG) recommends that you only gain between 25 and 35 pounds throughout the entire 40 weeks of gestation.

What is the Recommended BMI for Pregnant Women? 

These recommendations will change for women with higher or lower BMIs, as well as for pregnant women expecting multiples.

How Much Weight to Gain During Pregnancy When You’re Underweight? 

 Pregnant women who are underweight should be gaining more pounds throughout their pregnancy – between 28-40 pounds. 

How Much Weight to Gain During Pregnancy When You’re Overweight? 

Overweight and obese women need to be gaining less than the general pregnancy weight gain: between 11 and 20 pounds, depending on the exact pre-pregnancy weight. 

If you are unsure about your weight and how much you should be losing or putting on during your pregnancy, it is important to speak to your provider about this at the start of your pregnancy. Your weight during your pregnancy is something to be taken seriously. 

Is Dieting During Pregnancy and Pregnancy Weight Loss OK?  

Dieting with the intent to lose weight is not typically recommended during pregnancy, even if you begin pregnancy as overweight or obese. Intentional weight loss or restricted weight gain can affect fetal growth and well-being of the fetus. 

Losing weight during pregnancy increases the risk of having a small-for-gestational-age (SGA) infant, and associated complications of an SGA infant. Any weight concern should be discussed with your provider to ensure an adequate intake of vital nutrients during pregnancy.

There are conditions associated with pregnancy that may cause temporary weight loss, most being in the first trimester. This is followed by pregnancy weight gain during the second and third trimesters, where gaining one to two pounds per week is normal during this time frame. 

It is important to be mindful of expected weight changes and potential causes and to notify your provider of any concerns. 

Any unintentional or sudden weight loss during pregnancy is a concern that should be taken seriously.

Potential causes of weight loss during pregnancy

1. Morning Sickness

It should come as no surprise that 70–85% of all pregnant women experience nausea and vomiting in pregnancy. Thus, many women lose their appetites, and a few pounds, during the first trimester when this symptom is most common. As long as you are managing to eat a little, staying hydrated, and are not losing more than a few pounds, moderate morning sickness is not something to be worried about. 

However, it is important to distinguish between regular morning sickness and a condition referred to as hyperemesis gravidarum (HG).

HG is an extreme form of morning sickness that can lead to severe vomiting, dehydration, electrolyte imbalances, and even hospitalization. Moreover, this condition does not subside after the first 12 weeks. 

It is imperative that if you are experiencing these symptoms you speak with your provider to find ways to cope. Depending on the amount of weight you are losing, it could increase your risk of complications like low birth weight and preterm birth.

2. A Change in Daily Habits 

Another common reason for weight loss in early pregnancy is the sudden prioritization of one’s health. It’s easy to push off maintaining a healthier diet or incorporating more exercise into our daily routines…most of the time.

 But when suddenly tasked with growing another human being, many women quickly implement healthy eating habits and engage in safe exercise programs like prenatal yoga, which can cause a drop in weight. 

During pregnancy, excess calories from alcohol are also eliminated and replaced with water. This not only remedies symptoms like constipation and hemorrhoids, but it also facilitates the production of amniotic fluid and the development of the placenta. Additionally, drinking more water stimulates your metabolism and suppresses your appetite.

Research shows that dietary and nutritional interventions and exercise in pregnancy are associated with a reduced risk of hypertension, pre-eclampsia and gestational diabetes. However, these changes should only be done under the advice and supervision of your provider.

3. Third Trimester Symptoms Activities 

​Within the last few weeks of pregnancy, some women will experience a halt in their weight gain or they may even notice a small amount of weight loss. This may be normal. In the days and weeks before labor, many women also notice more bowel movements and a decreased appetite. 

To continue (getting) proper nutrients, consider smaller healthy snacks throughout the day, or protein shakes.

In addition, those who are determined to test the old wives’ tale that increased physical activity will induce labor will suddenly be burning extra calories. Nesting can have a similar effect. All of these factors can lead to a small amount of weight loss.

4. Oligohydramnios

 One third-trimester symptom that can be a cause for concern is Oligohydramnios (low amniotic fluid). 

Oligohydramnios can occur due to a placental abruption, your water breaking early, or a handful of other health conditions that may be impacting you or your baby. Signs that you have this condition include low kick counts and fluid leaking from your vagina.

For those women who are having trouble retaining their urine, the best way to determine if it is amniotic fluid and not urine is simple. Empty your bladder and put on an unscented panty liner. 

Wear it for an hour and then inspect the liquid. If it is clear and odorless, it is likely amniotic fluid. If it is yellow and or smells like ammonia, it is urine. Additionally, if the fluid stops leaking when tightening your pelvic floor muscles (like holding in urine), then it is likely urine. 

When you are noticing an early water break or are concerned about a potential early water break, it is imperative that you speak with your provider immediately.

5. Breastfeeding while Pregnant 

Expectant mothers who are simultaneously breastfeeding another child should consult their provider to make sure there is appropriate calorie intake. 

Breastfeeding can burn 500 to 700 calories per day, and if you are not consuming enough food to help recoup what you have lost, weight loss is inevitable and it may impact fetal development. 

In order for you to keep up your milk supply and facilitate proper baby growth throughout your pregnancy, it is extremely important that you focus on your diet and getting enough fuel and nutrients throughout the day. Talk to your provider about your specific needs and also stay vigilant with taking your prenatal vitamins and drinking plenty of water. These steps will ensure that you maintain a healthy weight.

When to See a Provider About Pregnancy Weight Loss 

It is important to remember that every pregnancy is different and that there are an array of factors that can impact your weight over the nine months you are pregnant. Try to not calorie count or fixate on the numbers on your scale unless you experience a drastic or sudden change, or have other symptoms that are a cause for concern.

If you are experiencing weight loss and common causes, such as morning sickness, are not to blame, it could be that there is a more serious underlying cause of your weight loss. More concerning causes to be evaluated include endocrine or autoimmune disorders, cancers, and infections. 

Additionally, since the second and third trimesters are times of fetal growth and weight gain, it is important to notify your provider of unexplained weight loss during this time. Your provider will have an extensive list of things that they will want to rule out, some serious. 

When it comes to the health and wellness of you and your growing baby, a healthy weight is essential. 

Pre-Pregnancy Weight Loss Considerations

Pre-pregnancy nutrition, exercise, and weight are associated with the health of the mother and baby during pregnancy. Being at an unhealthy weight (either overweight or underweight) at the time of conception increases the risk of medical conditions and complications during pregnancy. 

Those considering getting pregnant are encouraged to have a pre-conception visit with their healthcare provider. In addition to nutrition and weight considerations, other topics will be discussed to help encourage a healthy you, and the best possible start for your baby.