Minerals and trace elements in pregnancy in women with previous bariatric surgery Consequences on maternal and foetal health.

Background Bariatric surgery (BS) may decrease the risk of these obesity-related complications; however, due to its effect on nutrient intake and absorption, it can also have adverse consequences on maternal and foetal health. The aim of this study is to describe the evolution of electrolytes and trace elements serum levels throughout pregnancy after BS, according to the surgical technique and to evaluate the effect of nutritional deficiencies on the risk of maternal-foetal complications. Methods This is a retrospective observational study of the clinical evolution and maternal-foetal complications in a group of women with pregnancies that occurred after BS. Clinical evolution during pregnancy, body weight, and plasma electrolytes, vitamins, and trace elements, as well as their influence on maternal-foetal outcomes were evaluated. Composite neonatal variable (CNV) was defined to evaluate unfavourable foetal outcome. Published reference values for micronutrients during pregnancy have been used. Results The study includes data on 164 singleton pregnancies in 91 women. A hundred and twenty-seven pregnancies got to full term. The average birth weight was 2966 (546) g., 26.8% < P10 and 13.8% < P3 of a reference population. New-born of gestations after malabsorptive bariatric surgery had a higher risk of having a percentile of birth weight < P3. Plasma electrolytes, trace elements and vitamins throughout pregnancy showed differences depending on the surgical technique, with lower haemoglobin, ferritin, calcium, zinc, copper, vitamin A and vitamin E in the malabsorptive techniques. A high percentage of deficiency was observed, especially in the third trimester (Hb < 11g/dl: 31.8%; ferritin < 30mg/ml: 85.7%; zinc < 50μg/dl: 32.4%, vitamin D < 30ng/ml: 75.5% and < 20ng/ml: 53.3%). A decreased plasma copper in the first trimester or zinc in the third trimester were associated with a lower percentile of new-born birth weight. A higher risk of CNV was observed in predominant malabsorptive BS and in pregnancies that had presented at least one vitamin D level lower than 20ng/ml throughout pregnancy (30.4% vs. 7.1%, p=0.018). Conclusions Trace elements and vitamin deficiencies are common in pregnant women after bariatric surgery, especially of iron, zinc, and vitamin D. These deficiencies might negatively affect foetal development. Further studies are needed to better define the role of micronutrients in maternal-foetal health after bariatric surgery.