Laboratory testing for and diagnosis of nutritional deficiencies in pregnancy before and after bariatric surgery

Abstract

Objective: Bariatric surgery can reduce the risk of obesity-related complications of pregnancy, but may cause essential nutrient deficiencies. To assess adherence to laboratory testing guidelines, we examined frequency of testing for and diagnosis of deficiency during preconception and pregnancy using claims data in women with a delivery and bariatric surgery.

Methods: Retrospective analysis of claims from seven Blue Cross/Blue Shield plans between 2002 and 2008. We included women with a delivery and bariatric surgery within the study period. We used common procedural terminology (CPT) and ICD-9 codes to define laboratory testing and deficiencies for iron, folate, vitamin B12, vitamin D, and thiamine. Using Student's t-test and chi-square testing, we compared frequency of laboratory tests and diagnoses during 12 months preconception and 280 days of pregnancy between women with pregnancy before versus after surgery. We used multivariate logistic regression to evaluate for predictors of laboratory testing.

Results: We identified 456 women with pregnancy after bariatric surgery and 338 before surgery. The frequency of testing for any deficiency was low (9%-51%), but higher in those with pregnancy after surgery (p<0.003). The most common deficiency was vitamin B12 (12%-13%) with pregnancy after surgery (p<0.006). Anemia and number of health provider visits were independent predictors of laboratory testing.

Conclusion: Women with pregnancy after bariatric surgery were tested for and diagnosed with micronutrient deficiencies more frequently than those with pregnancy before surgery. However, most laboratory testing occurred in less than half the women and was triggered by anemia. Increased testing may help identify nutrient deficiencies and prevent consequences for maternal and child health.

FIG. 1.

Enrollment flow for selection of study sample.

FIG. 2.

Differences before and after bariatric surgery determined using χ² test. Syphilis screening during pregnancy is the control measure. All comparisons other than the control measure of prenatal syphilis screening are p<0.001.