P2.126: Developmental Origins of Iron Status in Infants Born to Post-Bariatric Surgery Mothers

Background: Bariatric surgery and pregnancy are independent risk factors for iron deficiency and anemia; however, few studies evaluate their co-occurrence and concomitant impact on maternal and infant iron nutrition status.

Methods: This analysis utilized a retrospective cohort review of a Bariatric Surgery registry and the electronic health record (EHR) to identify female Geisinger patients aged 18+ with body mass index (BMI)>35 kg/m2 who had bariatric surgery (e.g., Roux-en-Y gastric bypass (RYGB), Sleeve, or Biliopancreatic diversion with duodenal switch (BPD-DS)) between 2005 - 2023 and subsequently delivered a baby at Geisinger. Additional maternal inclusion criteria were hemoglobin and ferritin measured pre-bariatric surgery; and body weight, hemoglobin, and ferritin measured after bariatric surgery and pre-pregnancy. A multiple regression model was used to evaluate infant gestational age (pre- vs. full-term), birth weight, and hemoglobin levels in the first two years of life in association with maternal factors including time from bariatric surgery to delivery ( < 2 years, ≥2 years but < 4 years, ≥4 years); maternal hemoglobin and ferritin (pre-bariatric, pre-pregnancy), and maternal BMI (pre-bariatric and pre-pregnancy) and percent weight loss between bariatric surgery and pregnancy.

Results: Inclusion criteria resulted in N=172 eligible patients. At the time of bariatric surgery, mothers had a mean age of 29.7 (SD=4.5) and BMI of 47.7 kg/m2 (SD=7.5). Majority (76%) identified as Non-Hispanic White, then as Hispanic (15%) and Non-Hispanic Black (9%). RYGB was most common (79%) followed by sleeve (17%) and BPD-DS (4%). A < 2-year interval from surgery to delivery was associated with 0.8gm/dL lower infant hemoglobin (p=0.0065). Low mother ferritin pre-bariatric surgery and pre-pregnancy was associated with 3.2 gm/dL lower infant hemoglobin (p < 0.0001). Low mother hemoglobin ( < 12) pre-bariatric surgery and pre-pregnancy was associated with 3.8 gm/dL higher infant hemoglobin (p < 0.0001). Highest quartile of % weight loss from bariatric surgery to pre-pregnancy (>=37.6%) was associated with 1.8 gm/dL higher infant hemoglobin (p < 0.0001). Gestational age and birth weight were not significantly associated with maternal iron status or BMI.

Conclusion: Pregnancy after bariatric surgery poses unique demands on maternal iron levels. These results indicate that maternal iron deficiency increases the risk of low iron in her offspring during early life. Increasing the length of time between surgery and conception and improving pre-surgical and pre-pregnancy iron stores are two possible approaches to mitigate such risks. Conversely, infant hemoglobin was inversely associated with low maternal hemoglobin prior to surgery and pregnancy. Future research is needed to elucidate the relationship between maternal iron status as it relates to infant iron status and development.