What Can Happen If You Lose Weight During Pregnancy?

Many women consider weight loss a positive development under normal circumstances. Weight loss during pregnancy can be alarming, however, because it is the opposite of what a woman expects. According to the Mayo Clinic, women should gain between 11 and 40 pounds during pregnancy, depending on their starting weight. Weight loss can occur for many reasons during pregnancy, some of which are more serious than others.

Starting Weight

You need to gain more weight if you begin your pregnancy underweight than if you were a normal weight or overweight before you conceived. Women who begin pregnancy overweight need to gain less weight. Baby Center does not recommend dieting during pregnancy but reports that some plus-size women actually lose a few pounds while pregnant. If your doctor is monitoring you and you are not intentionally dieting, this weight loss may be benign.

Early Pregnancy Weight Loss

Weight gain is most important in later pregnancy. Like many women, you may feel nauseated owing to morning sickness in your first trimester, which may result in weight loss. Your baby will not begin to gain weight until later in your pregnancy, so you can lose weight early in pregnancy but still have a net weight gain by the end.

Hyperemesis Gravidarum

Hyperemesis gravidarum is a rare condition of extreme morning sickness that causes vomiting, dehydration and weight loss. According to the American Pregnancy Association, hyperemesis gravidarum occurs in about 1 percent of all pregnancies. If you have this condition, your doctor must monitor you and may hospitalize you to receive intravenous fluids.


Although you should never go on a diet to lose weight during pregnancy, you should also avoid excessive weight gain. Consult a dietitian if you are finding it difficult to manage your diet and weight during pregnancy. Ask your doctor for reassurance and additional monitoring if you are worried about your pregnancy weight loss as well. Your body will use your fat stores to nourish the baby even if you are losing weight, but this process can be risky for your health.

Effects of Weight Loss

Weight loss during pregnancy should not harm your baby because your body will take the nutrients it needs from your stored reserves. Your own health may suffer as a result, however. You may feel more tired and could be more susceptible to infections. Weight loss may be less problematic if you began the pregnancy overweight because your body has more fat stores from which to draw. Ask your doctor or midwife to monitor your weight loss and help you watch for complications.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.
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