SMFM Clinical Practice Guidelines Assessing nutritional needs in pregnant patients with prior bariatric surgery Society of Maternal Fetal Medicine with the assistance of Donna Johnson, MD Published in Contemporary OB/GYN / Oct2013

Type of weight loss surgery  Bariatric surgery can cause weight loss through intake restriction, food malabsorption, or a combination of these.  The 2 most common bariatric procedures performed in the United States in reproductive-age women are Roux-en-Y gastric bypass (65%) and adjustable gastric banding (24%).  Roux-en-Y gastric bypass restricts intake and food absorption, whereas adjustable gastric banding limits only food intake.  Other bariatric surgeries are performed but are much less common. Today, biliopancreatic diversion is rarely performed because it is associated with a higher mortality rate and more significant nutritional deficiencies.  Vertical banded gastroplasty and sleeve gastrectomy are both restrictive surgeries.

What nutritional deficiencies are obstetrical patients at risk for after bariatric surgery?  Nutritional deficiencies are frequently encountered in patients who have undergone bariatric surgery and they can be amplified during pregnancy. Malabsorptive procedures are associated with more nutritional deficiencies than is restrictive surgery, as outlined in Table

What nutritional deficiencies are obstetrical patients at risk for after bariatric surgery?  Nonpregnant patients who have had bariatric surgery are commonly prescribed a variety of nutritional supplements because of nutritional deficiencies. Table 2 outlines examples of some of these routine supplements.

Antenatal Care  When a patient who has undergone bariatric surgery becomes pregnant, a detailed history should be obtained at the first prenatal visit.  Patients with prior bariatric surgery may have unique nutritional deficiencies that are not routinely considered in healthy obstetric patients.  These deficiencies may cause health problems. Persistent complaints such as muscle pain or cramps, easy bruising and/or skin and mucosal changes in a pregnant patient may be symptoms of vitamin or micronutrient deficiencies. These may be more relevant if the patient is still in the rapid- weight-loss phase following her bariatric surgery.  Current guidelines suggest checking serum levels of vitamin B12 and folate during pregnancy in women with prior bariatric surgery, along with a complete blood count, iron, ferritin, calcium, and vitamin D levels; measurement every trimester has been suggested.

Special considerations for nutrient replacements after bariatric surgery  In patients who have had bariatric surgery, stomach pH is altered and the surface area for absorption decreases. These changes may warrant manipulation in the preparation, route, or dose of nutrient replacements. Liquid or chewable vitamins are better absorbed than tablets.  Calcium carbonate depends on acid for absorption, whereas calcium citrate does not; therefore, calcium citrate is the recommended replacement.  Administration of iron simultaneously with vitamin C improves iron absorption because the vitamin C helps to acidify the stomach.  Absorption of oral vitamin B12 depends on intrinsic factor produced by the parietal cells of the stomach, and production of intrinsic factor may be significantly altered when a part of the stomach is surgically removed. Therefore, even with adequate oral supplementation in a patient with malabsorptive surgery, a nutritional deficiency in vitamin B12 may not be corrected and intramuscular injections may be required.  Because of reduced drug absorption, periodic monitoring of nutritional levels is suggested to ensure adequate replacement.

Special nutritional considerations for pregnant women who have had bariatric surgery  Some women with malabsorption resulting from bariatric surgery may have vitamin A deficiency. High levels of vitamin A intake have been associated with fetal anomalies.  Currently human evidence is insufficient to establish a safe threshold for daily intake. The maximum amount of vitamin A recommended for pregnant women is 8000 to 11,000 IU per day or not more than 5000 IU in supplements.  Bariatric surgery patients are at particular risk of anemia, which is also common during pregnancy. If common causes of anemia like iron deficiency, vitamin B12 or folate deficiency, and hemoglobinopathy are excluded, clinicians should consider less-common causes of nutritional anemia, such as copper deficiency.

Follow up  Care should be taken when administering screening tests for gestational diabetes.  In about 50% of patients who have Roux-en-Y gastric bypass, dumping syndrome can occur. It is characterized by symptoms including a shaky, sweaty, dizzy sensation accompanied by a rapid heart rate and, occasionally, by severe diarrhea.  Alternative methods, such as home glucose monitoring or hemoglobin A1C measurement, may be considered.

Summary  Patients who undergo bariatric surgery, especially malabsorptive procedures, are at increased risk of nutritional deficiencies.  Pregnancy may make some of these nutritional deficiencies more severe by increasing demand or decreasing intake, especially if a patient has nausea and vomiting.  The evidence for monitoring of nutritional deficiencies and for supplementation is insufficient to make any strong recommendation, and more research is needed.  Patients should continue to receive monitoring and supplementation as needed, in collaboration with the bariatric surgery team and medical specialists, and the ob/gyn should remain vigilant for signs and symptoms of nutritional deficiencies.  With careful monitoring, women with bariatric surgery are likely to have normal pregnancy outcomes.

 The practice of medicine continues to evolve, and individual circumstances will vary. This opinion reflects information available at the time of its submission for publication and is neither designed nor intended to establish an exclusive standard of perinatal care. This presentation is not expected to reflect the opinions of all members of the Society for Maternal-Fetal Medicine.  These slides are for personal, non- commercial and educational use only Disclaimer

Disclosures  This opinion was developed by the Publications Committee of the Society for Maternal Fetal Medicine with the assistance of Stanley M. Berry, MD, Joanne Stone, MD, Mary Norton, MD, Donna Johnson, MD, and Vincenzo Berghella, MD, and was approved by the executive committee of the society on March 11, Dr Berghella and each member of the publications committee (Vincenzo Berghella, MD [chair], Sean Blackwell, MD [vice-chair], Brenna Anderson, MD, Suneet P. Chauhan, MD, Jodi Dashe, MD, Cynthia Gyamfi-Bannerman, MD, Donna Johnson, MD, Sarah Little, MD, Kate Menard, MD, Mary Norton, MD, George Saade, MD, Neil Silverman, MD, Hyagriv Simhan, MD, Joanne Stone, MD, Alan Tita, MD, Michael Varner, MD) have submitted a conflict of interest disclosure delineating personal, professional, and/or business interests that might be perceived as a real or potential conflict of interest in relation to this publication.