Monitoring Nutritional Consequences of Obesity Treatment on Women's Health

The goal of this observational study is to investigate the long-term effect of obesity treatments on the health of women. This study will specifically focusses on the effects on nutritional intake, nutritional status, musculoskeletal health and reproductive health. Additionally, this study will also investigate the effect of obesity treatment on pregnancy outcomes and child development.

To achieve the goal of this study, participants already receiving either surgical treatment for obesity or treatment with anti-obesity medication as part of their regular medical care will fill in additional questionnaires, provide blood, urine and feces samples, and undergo additional measurements of body composition and muscle strength up to for 10 years.

The MONUCO study is a multicenter 10-year prospective observational cohort study with an integrated birth cohort. Women between the ages of 18-55 years approved for either surgical or pharmacological obesity treatment at one of the participating centers are invited. Follow-up data will be collected at 6-weeks pre-treatment, three months, six months and one year up to ten years post-surgery. At each time point, participants fill in questionnaires on lifestyle factors, gastrointestinal complaints, menstrual and postmenopausal complaints, and mental health. They also record their dietary intake using FFQ's and a 2h-recall method via the Traqq application. Additionally, they provide blood, urine and feces samples which are stored at -80 degrees Celsius for future analysis. During a study visit at each time point, height, weight, hip and waist circumference is measured as well as body composition with BIA and muscle strength and balance with handgrip strength and a timed chair-stand test. In a subgroup of the study population, a DEXA scan and/or MRI scan is performed and physical activity is tracked with an accelerometer.

Women who become pregnant during the follow-up period will be included in the integrated birth cohort. To supplement this number, pregnant women who have had obesity treatment who are not a part of the overall cohort are also invited. Within the integrated birth cohort, measurements are collected at each trimester during pregnancy and two months post-partum, six months post-partum, after one year up to four years after pregnancy. During pregnancy, the participant fill in questionnaire on lifestyle factors, gastrointestinal complaints and pregnancy-related complaints as well as record dietary intake with an FFQ and 2h-recall method. In this group also provides blood, urine, stool and human milk samples.

Eligibility Criteria:
General Inclusion Criteria:

* Female sex at birth
* Aged 18-55 years of age
* Living with obesity (BMI ≥ 30 kg/m2)
* Approved for obesity treatment in one of the participating hospitals:
* Undergoing primary bariatric surgery (RYGB, OAGB or SG)
* Receiving obesity medication (any type) with a BMI ≥30 kg/m2 under medical supervision.
* For those undergoing MRI, DEXA and quantitative ultrasound scan: Willing to be informed about incidental findings of pathology and approving of reporting this to their general physician.

Additional inclusion criteria for birth cohort:

* Being pregnant
* Age 18-45 years of age
* Having received prior obesity treatment, either surgical (RYGB, OAGB, SG) or pharmacological for at least 4 months under medical supervision (any type).

General Exclusion Criteria:

* Male sex at birth
* Aged \<18 or \>55 years of age
* BMI \<30 kg/m2
* Not able to read and/or write in Dutch
* Undergoing a revisional or secondary bariatric procedure (excluding previous gastric banding)
* Malnutrition due to other chronic condition, specifically malignancy, substance abuse
* (mental) condition that makes it impossible to fill out a questionnaire correctly.
* For those undergoing a DEXA scan: height \>196 cm or weight \>160 kg
* For those undergoing a MRI scan: having a contra-indication to MRI scanning including (but not limited to) pacemakers and defibrillators, intraorbital or intraocular metallic fragments, ferromagnetic implans or claustrophobia.

Additional exclusion criteria birth cohort:

* Aged \<18 or \>45 years of age
* \>25 weeks of gestation
* Multiple pregnancy
* Reversal of the bariatric procedure