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Harvard Commentaries
Harvard Commentaries
Reviewed by the Faculty of Harvard Medical School

Food for Thought Food for Thought

Pregnancy After Weight-Loss Surgery

October 23, 2014

By Marsi Shapiro, B.S.
Brigham and Women's Hospital

More than one-third of U.S. adults (35.7%) are obese. This is alarming.

From 1998 to 2005, there was a six-fold increase in the number of weight-loss surgeries – also called bariatric surgery. More than half of these procedures were in women of childbearing age (18-45 years old). In 2003 alone, 84% of the 103,000 gastric bypass surgeries were performed on women of childbearing age.

As more women of childbearing age are having weight-loss surgery, it raises questions about its impact on fertility and subsequent pregnancy.

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Nutritional Risks After Surgery

Bariatric surgery increases the risk for nutrient deficiencies. The severity of risk depends on the type of procedure a person has had. Here's how they rank from lowest to highest risk:

  • Adjustable gastric banding
  • Vertical sleeve gastrectomy
  • Roux-en-Y gastric bypass
  • Bilio-pancreatic diversion

Nutritional deficiencies are caused by decreased:

  • Absorption of nutrients from food
  • Secretion of stomach acid to aid in digestion and absorption
  • Intake of nutrients as a result of food intolerances, chronic nausea, vomiting and/or diarrhea

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Timing Your Pregnancy

It is recommended that women wait 12-18 months after surgery before trying to conceive because of the rapid weight loss and risk of nutritional deficiencies right after surgery.

Getting adequate nutrition during pregnancy is hard enough. Further nutritional losses may prevent the developing baby from getting the nutrients it needs.

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Weight Gain

Appropriate weight gain is important for a healthy pregnancy.

The amount of weight a woman needs to gain during pregnancy is based on her body mass index (BMI) before pregnancy, according to the Institute Of Medicine, 2009.

Pre-pregnancy weight


Weight gain in pounds (singleton)

Average weight
Overweight (>120% ideal body weight)
Obese Class I
Obese Class II
Obese Class III

A woman who gets pregnant less than 6 months after surgery needs to slow down or minimize weight loss. Spreading food over 4 or 5 meals or snacks daily will help to increase intake slowly and comfortably. For pregnancies more than 6 months after surgery, the goal is to add 300 calories daily to the regular postoperative diet (1,200-1,500 calories per day). This will help promote a healthy weight gain.

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Getting Enough Protein

Eating enough protein during pregnancy is crucial for supporting your baby's growth and development. However, protein intake may be difficult as many protein-rich foods are not well tolerated post surgery.

To increase protein intake, eat protein before other types of foods. Chew food thoroughly and consume smaller, more frequent meals and snacks rather than larger meals.

Include the following protein-rich foods as tolerated into your daily diet.

Animal proteins


Soy products


Chunk light tuna*
Yogurt (Greek)
High protein/low sugar protein shake**
Pasteurized cheese
Cooked beans
Sugar-free pudding (made with milk)
Soy milk
Peanut butter (and other nut butters)

*Bolded foods are usually better tolerated
**Liquid protein supplements should be low in sugar and without sugar alcohols for better tolerance

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Getting Enough Fluids

Dehydration is common after weight-loss surgery. Patients have limits on how much they can drink. And vomiting and diarrhea are common. These can cause fluid loss. On top of those challenges, pregnancy increases fluid needs and also contributes to nausea, vomiting and diarrhea.

The recommended total fluid intake during pregnancy is 8 to 10 cups (about 64 ounces) per day. This includes all fluids, not just water: hot and iced decaf tea, milk, soups and calcium-fortified juice.

Here are some tips to help you get enough fluids:

  • Sip fluids throughout the day. Carry a water bottle as a reminder to drink.
  • Add flavor to water. Consider lemon, lime, orange or cucumber slices.
  • Avoid carbonated and caffeinated drinks. Carbonation might lead to unwanted gas or stomach cramping; caffeine may increase risk of dehydration.
  • Avoid drinking 30 minutes before or 30 minutes after a meal. You may feel too full to eat.

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Vitamin and Mineral Supplementation

People who have weight-loss surgery need to take supplements for the rest of their lives.

Women who become pregnant after surgery may need additional supplementation. To ensure proper nutrition for both you and your baby, your doctor will order blood tests to check for vitamin and mineral deficiencies. The most common ones for pregnant women after surgery include folic acid, iron, calcium, vitamin D and vitamin B12.

Here's a comparison of the supplements needed for pregnant and non-pregnant women after surgery.

Non-pregnant women

Pregnant women

1 or 2 multivitamins
1 prenatal vitamin*
1,000 milligrams calcium citrate with 400 IU vitamin D
1,200 -1,500 milligrams calcium citrate with 400 IU vitamin D
500 micrograms vitamin B12 (your doctor will check your levels to see if you need supplementation)
500 micrograms vitamin B12 (your doctor will check your levels to see if you need supplementation )
40-100 milligrams elemental iron for pre-menopausal women
Your doctor will check your levels to see if you need supplementation.

*There is no one standard prenatal vitamin

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Other Considerations

Weight-loss surgery and subsequent weight loss improve fertility in overweight and obese women. So doctors encourage using reliable forms of contraception during the waiting period (12-18 months after surgery) to prevent pregnancy before weight loss has stabilized.

Women who have had an adjustable band procedure may have the band deflated or loosened during pregnancy. This will help increase your food and fluid intake, if necessary, and help relieve severe nausea and vomiting as a result of gastric banding or morning sickness.

Generally, all women are checked for gestational diabetes by the 28th week of pregnancy. This is a form of diabetes that occurs during pregnancy. Testing for gestational diabetes requires drinking a very sweet beverage. Weight-loss surgery patients may find this drink difficult to tolerate. Discuss this with your obstetrician to consider alternative tests that may be performed.

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The Bottom Line

The key things to keep in mind about getting pregnant after weight-loss surgery are:

  1. Pregnancy after bariatric surgery poses higher nutritional risks.
  2. Talk frequently to your obstetrician, bariatric surgeon and dietitian.
  3. Appropriate weight gain is crucial for a healthy pregnancy outcome.
  4. Eat enough protein and drink enough fluids.
  5. Take your nutrition supplements.

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Marsi Shapiro graduated from Cornell University with a B.S. in Nutrition and a concentration in dietetics. She completed her dietetic internship at Brigham and Women's Hospital in August 2012 and plans to become a registered dietitian. She has a strong interest in clinical dietetics, sports nutrition and prenatal nutrition.

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