Management of pregnancy in women with history of weight loss surgery

The proportion of the female population either overweight or obese has increased significantly in recent years and pregnancy in this group of women is associated with significant health problems.

Pregnancy in obese women is associated with increased risk of metabolic syndrome, including impaired glucose tolerance and raised blood pressure.

Of late, more and more young women are seeking bariatric surgery (BS) where nonsurgical methods have failed to achieve or maintain significant weight loss.

A Cochrane review has concluded that that BS is more effective and cost-effective than nonsurgical measures in patient’s follow-up for 2 years with measurable long-term health benefits.

Women with a history of BS are a challenge for an obstetrician in antenatal clinic due to their unfamiliarity with the issues surrounding the surgery.

This unfamiliarity creates the risk that women may be suboptimally managed and that serious complications may go unrecognized resulting in morbidity.

Restrictive procedures:

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  these surgical procedures reduce oral intake by minimizing the available space in their stomach: laparoscopic adjustable gastric banding (LAGB) and laparoscopic sleeve gastrectomy.

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  In LAGB, an inflatable band is positioned around the fundus of a patient’s stomach. A variable amount of sterile water is injected into the band via tubing and it reduces stomach volume to a small pouch above the band.

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  In laparoscopic sleeve gastrectomy, a narrow gastric sleeve is created by removing the greater curvature of the stomach.

Malabsorptive procedures:

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  These procedures are rarely performed especially in young women with reproductive potential.

Combination of restriction and malabsorption:

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  Roux-en-Y gastric bypass is an example of a combined procedure. This operation creates not only anatomical restriction but also has an element of malabsorption.

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  In this operation, the stomach is restricted into a smaller gastric pouch with its contents directed via a food channel into the jejunum, bypassing the main body of the stomach and the duodenum, resulting in malabsorption.

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  This type of surgery does result in better weight loss compared to purely restrictive procedures.

BS is associated with deficiency of essential nutrients (folate, vitamin D, vitamin B12, calcium, iron, and copper).

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  Folic acid absorption is reduced because of reduced production of gastric acid secretion and reduced surface area of small intestine, thus increasing risk of macrocytic anaemia in mother and neural tube defect in the baby.

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  Vitamin B12 deficiency is quite high after BS. This is secondary to reduced secretion of intrinsic factor, reduced acidity, and lack of absorption in duodenum (where bypassed), with possible risk of macrocytic anaemia.

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  There is increased risk of iron malabsorption due to an increase in gastric pH and restriction of iron absorption in duodenum and ileum. This would increase risk of iron deficiency anaemia and neonatal anaemia. If unable to tolerate oral iron supplements, then intravenous administration should be considered.

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  Vitamin A is fat soluble and there is a strong association of retinol isoforms with foetal malformations. The deficiency also increase risk of nocturnal blindness.

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  Vitamin B1 deficiency can be exacerbated by nausea and vomiting of pregnancy. There is a case report of Wernicke’s encephalopathy in a pregnancy following BS.

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  Calcium and vitamin D are mainly absorbed in small intestine and will require close monitoring and supplementation. Women who have undergone a procedure involving partial gastrectomy or gastric bypass require large doses of vitamin D supplementation.

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  Dietary recommendations for post BS are shown in Table 31.1 .

  Table 31.1

  Recommended dose of supplements for pregnant women after bariatric surgery.

  Folic acid	5 mg daily preconception until the end of the first trimester
  Thiamine	12–50 mg daily, extra 200–300 mg if vomiting
  Vitamin B12	1000 μg daily or 1000 μg IM injection 4–12 weekly
  Iron	45–60 mg daily, consider IV if persistently low despite oral replacement
  Calcium	1500 mg daily
  Vitamin D	Routine replacement not recommended unless testing identifies a deficiency
  Vitamin A	1000–5000 IU daily in the form of beta-carotene
  Vitamin E	15 mg daily
  Vitamin K	90–300 μg daily