Maternal Anthropometry and Its Relationship with the Nutritional Status of Vitamin D, Calcium, and Parathyroid Hormone in Pregnant Women After Roux-en-Y Gastric Bypass

Abstract

Objective: To assess the influence of pre-pregnancy body mass index (BMI), total gestational weight gain (TGWG), and pre-pregnancy surgical success on the nutritional status of vitamin D, calcium, and parathyroid hormone (PTH) in the trimesters of pregnancy of women who previously underwent Roux-en-Y gastric bypass (RYGB).

Methodology: This is an analytical, longitudinal, and retrospective study comprising 42 pregnant women who previously underwent RYGB. Concentrations of vitamin D₃, calcium, and PTH were assessed in all trimesters. Anthropometric variables necessary for calculating TGWG, surgical success, and BMI were collected preoperatively and over the trimesters of pregnancy.

Results: A total of 97.1% had vitamin D₃ inadequacy at some point in pregnancy. Pre-pregnancy BMI, even when classified as overweight, may have exacerbated the serum concentrations of this vitamin in the third trimester (p = 0.011), and it was significantly lower in women with normal weight and/or obesity (p = 0.039). It was evidenced that both pre-pregnancy BMI and TGWG above the recommended optimal weight can be associated with calcium homeostasis, especially early in pregnancy. It was also shown that surgical success in the pre-pregnancy period may have influenced the serum concentrations of vitamin D in the second trimester of pregnancy (p = 0.013).

Conclusion: This study draws attention to the importance of monitoring the nutritional status of vitamin D₃ and calcium in the prenatal period due to its relationship with pre-pregnancy BMI, TGWG, and surgical success.

Keywords: Bariatric surgery; Body mass index; Calcium; Obesity; Pregnancy; Roux-en-Y gastric bypass; Vitamin D.