Impact of diet and bariatric surgery on anti-Müllerian hormone levels

STUDY QUESTION: Do serum levels of anti-Müllerian hormone (AMH) change in women of reproductive age following dietary and surgery-induced weight loss?

SUMMARY ANSWER: AMH levels increased after very low-calorie diet (VLCD) before surgery and decreased at 6 and 12 months after Roux-en-Y gastric bypass (RYGB), beyond expected normal age-related decline.

WHAT IS KNOWN ALREADY: Obesity has negative effects on fertility and IVF outcomes, and possibly also on AMH levels. AMH correlates to the number of growing follicles and is used to predict the response to IVF treatment. However, AMH might decrease after bariatric surgery.

STUDY DESIGN, SIZE, DURATION: A prospective cohort study of 48 women followed first for 8 weeks preoperatively, then operated with RYGB and followed postoperatively for 1 additional year.

PARTICIPANTS/MATERIALS, SETTING, METHODS: Women aged 18-35 years with a mean (SD) BMI 40.9 (3.6) kg/m2 were included at baseline (BL). After the VLCD, a RYGB was performed. Body weight and height were measured at BL and 1 year postoperatively. Hormones were analysed at BL, after VLCD on the day before surgery, and at 6 and 12 months postoperatively.

MAIN RESULTS AND THE ROLE OF CHANCE: Median AMH levels were 30.0 pmol/L at BL and rose significantly after VLCD (median: 35.0 pmol/L; P = 0.014). Median AMH at 6 and 12 months postoperatively were significantly lower (19.5 and 18.0 pmol/L, respectively; P = 0.001). Free androgen index (FAI) was significantly lower after 12 months, compared to BL (1.2 vs 3.5, P < 0.0005).

LIMITATIONS REASONS FOR CAUTION: Ultrasound for PCOS diagnosis was not performed. The change in laboratory methods for AMH analysis during the study might be a limitation.

WIDER IMPLICATIONS OF THE FINDINGS: Obese young women might choose bariatric surgery also for fertility reasons, and the observed decrease in FAI is in line with improved fertility. More research is needed to evaluate the clinical effects of the decrease of AMH, and the effect of bariatric surgery prior to IVF treatment.

STUDY FUNDING/COMPETING INTEREST(S): Study-specific laboratory analyses were funded by the Swedish Regional Research Fund (ALF). Authors declare no competing interests.

TRIAL REGISTRATION NUMBER: N/A.