Towards a multidimensional scientific approach to improve clinical practices for infertility treatment.

Polycystic ovary syndrome (PCOS) is the most common metabolic and endocrine disorder in women, leading to infertility. However, there is no general agreement concerning how to diagnose and treat PCOS. The Rotterdam consensus statement from the European Society of Human Reproduction and Embryology/American Society for Reproductive Medicine, the Chinese diagnostic criteria and consensus statement, and the clinical practice guideline from the Endocrine Society in the USA are widely recognized. Guidance has been provided for clinical practice based on a comparative analysis of the above three practice guidelines or consensus statements (Wang et al., 2018a). High body mass index (BMI) has no negative effect on the outcome of in vitro fertilization (IVF) in Chinese patients with PCOS; however, the conclusion may be limited by the retrospective design and potential bias (Pan et al., 2018). Neonatal birth weight is positively affected by both maternal pre-pregnancy body mass index (pre-BMI) and gestational weight gain (Du et al., 2017). Normal body weight is very important for conception. Women with PCOS are almost 3 times more likely to be obese than those without PCOS; however, no specific interventions are available to induce weight loss, and drugs are used to treat other symptoms of the syndrome or obesity in the general population. A network meta-analysis found that the amount of weight loss differed significantly according to the choice of drugs (in descending order): liraglutide, orlistat, and metformin. Liraglutide alone, liraglutide/metformin, and metformin alone significantly reduced waist circumference, but no change was found with orlistat, indicating liraglutide appears superior to the other drugs in reducing weight and waist circumference (Wang et al., 2018b). IVF, as a choice for more than 1 000 000 infertile couples each year, gives rise to the birth of over 3 000 000 babies worldwide.