Bariatric Surgery (BS) is a set of surgical techniques and procedures used in patients with severe obesity, aimed to achieve weight loss, maintained over time, and to improve associated diseases and quality of life [1]. BS decreases the risk of mortality and achieves a remission or improvement of most of the comorbidities [2], [3]. However, these procedures that are not risk free. Trace element, mineral and vitamin deficiencies are frequent and require a protocolized evaluation and treatment [4], [5].

Pregnancy in women with previous bariatric surgery deserves special consideration [6], [7], [8]. It is well known that obesity decreases fertility and increases the risk of maternal-foetal complications during pregnancy, such as gestational diabetes, hypertension and preeclampsia, childbirth problems, macrosomia, etc [9]. Bariatric surgery can decrease the risk of these obesity-related complications. However, due to its effect on nutrient intake and absorption, it may also have adverse consequences on maternal and foetal health [10], [11], [12], [13]. Although several studies have been published in recent years on the evolution and complications of pregnancy after BS, there is little information about the effect of the different BS techniques on the nutritional status of trace elements and vitamins during pregnancy and its clinical consequences on maternal and foetal health.

The aim of this study is to describe the plasma levels of trace elements and vitamins throughout pregnancy in women with previous bariatric surgery, depending on the type of surgical technique applied: predominantly malabsorptive bariatric surgery (MBS), Roux-Y-gastric bypass (RYGB) and bariatric gastric surgery (BGS). As a secondary objective, we propose to assess the relationship between deficiency of these elements and maternal and foetal health.