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Micronutrients, Bariatric Surgery, and the Obstetrical Patient

Micronutrients, Bariatric Surgery, and the Obstetrical Patient

With the rate of obesity growing as rapidly as our waist lines, it’s no surprise that a recent National Health and Nutrition Examination Survey determined that more than one third of all women are obese, half of all pregnant women are either overweight or obese, and 8% of reproductive-age women are morbidly obese.1

The World Health Organization categorizes obesity into the following 3 classes based on body mass index (BMI), measured in kg/m2:

▪ Class 1: BMI 30 - 34.99.
▪ Class 2: BMI 35 - 39.99.
▪ Class 3: BMI ≥ 40 (morbid obesity).

Overweight and obese obstetrical patients are at increased risk for a number of pregnancy complications, including gestational diabetes mellitus, hypertension, preeclampsia, cesarean delivery, venous thromboembolism, infection, fetal growth abnormalities, premature delivery, and possibly congenital anomalies. Therefore, patients who are overweight or obese should be counseled to lose weight before becoming pregnant. If they are unable to lose weight before becoming pregnant, managing weight gain during pregnancy becomes critical. Current recommendations for weight gain for singleton pregnancies are 15 to 25 lb for overweight women and no more than 11 to 20 lb for obese women.1

It is important to encourage weight loss in all of our patients who are overweight and obese. Some women are able to lose weight with diet and exercise, but many women struggle with weight loss or have trouble maintaining a weight loss. A subset of women has turned to bariatric surgery to help lose weight, and it is this group of women that I’d like to discuss.

When Lifestyle Changes Don’t Work

Bariatric surgery is an effective therapy for morbidly obese women both for weight loss and improvement of many of the comorbidities previously mentioned. Women accounted for 83% of all bariatric surgery procedures among 18- to 45-year-olds between 1998 and 2005.2 It is no wonder that we are seeing these women in our practices seeking obstetrical care.

The 2 most common bariatric surgical procedures performed in the United States on reproductive-age women are Roux-en-Y (65% of cases) and gastric adjustable banding (24% of cases).

The Roux-en-Y is considered to be both “restrictive and malabsorptive,” because it restricts the amount of food intake as well as the absorption of food since part of the intestinal tract is bypassed in this procedure. Because of the potential for malabsorption, up to 50% of these women may experience “dumping syndrome,” which manifests as shaking, sweating, dizziness, increased heart rate, and diarrhea.

The gastric banding procedure is referred to as “restrictive,” because it limits food intake and reduces the available surface area of the stomach.

Most bariatric surgeons recommend that women wait 12 to 18 months after bariatric surgery, which is considered the rapid weight-loss period, before attempting pregnancy (more on this study here).However, it has been reported that short-term perinatal outcomes of women who conceived during their first year after bariatric surgery (n=104) compared with those of women who conceived after their first year following surgery (n=385) were similar.4 In fact, there were no significant differences in birth weight, anemia, or preterm delivery between the two groups.

TABLE 1. THE MOST COMMON MICRONUTRIENT DEFICIENCIES IN PREGNANCY AFTER BARIATRIC SURGERY
Micronutrient Function
Vitamin B12 Red blood cell formation, neurological function, and DNA synthesis
Folate Synthesis of nucleic acids (DNA and RNA) and metabolism of amino acids
Vitamin B1 (Thiamine) Conversion of carbohydrates into energy
Fat-soluble vitamins:
  Vitamin A Immune function, vision, reproduction, cellular communication
  Vitamin D Calcium absorption for strong bones
  Vitamin E Antioxidant properties
  Vitamin K Blood coagulation
Calcium Blood flow, muscle function, nerve transmission, cellular communication, hormonal secretion
Iron Oxygen transport
Data from the National Institutes of Health, Office of Dietary Supplements. Available here.

Keep in mind that bariatric surgery may be an independent risk factor for premature delivery, although a recent study showed that this increased risk was only found in women who also had an early pregnancy BMI of 30 or below.5 Interestingly, women with a BMI of 35 or greater had no increased risk of premature delivery (more on this study here.)

Current ACOG guidelines suggest that pregnant women with a history of bariatric surgery should be evaluated for nutritional deficiencies, and women who have had a gastric band procedure should also be monitored by their general surgeon throughout their pregnancy because band adjustments may be needed.1 ACOG also advises that bariatric surgery is not itself an indication for cesarean delivery, although many women who have had surgery for weight loss deliver via cesarean section.

 

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