Scheme of measuring moments.
= online data collection. = fasting blood sample. = bariatric surgery. = pregnancy. = birth. = measuring moment. = breast milk samples. T1 (before surgery), T2 (3 weeks after surgery), T3 (3 months after surgery, T4 (6 months after surgery), T5 (12 or X months after surgery), T6 (1st trimester of pregnancy), T7 (2nd trimester of pregnancy), T8 (3rd trimester of pregnancy), T9 (birth), T10 (6 weeks postpartum), T11 (6 months postpartum)