At present, it is widely recognized that obesity can seriously affect the function of female reproduction, but the mechanism of action by which obesity affects women’s physiology is complex and has not yet been fully clarified. Obesity can lead to women’s menstrual irregularities, amenorrhea and ovulation disorders, thus causing infertility. 1, causing insulin resistance Research has proved that high insulin can directly inhibit the growth of follicles with a diameter of 5-10mm. At the same time, peripheral insulin resistance can eventually lead to an increase in insulin signaling in the ovaries (because the ovaries are abnormally sensitive to insulin response), resulting in the ovaries producing too much sex hormones. For example, it promotes androgen production, and hyperandrogenism affects follicular development and ovulation. Insulin resistance aggravates obesity, and androgen affects insulin sensitivity through its side effects, resulting in a vicious circle. 2, affect the production of sex hormones and ovarian function Secondly, fat itself is a highly active endocrine and metabolic organs, its abnormal metabolism directly affects the production of sex hormones and ovarian function, cumulative impact on female fertility, from follicle production, development, maturation to ovulation, fertilization, early embryonic development and a series of processes. 3, induced polycystic ovary syndrome Furthermore, obesity plays a crucial role in the occurrence and development of polycystic ovary syndrome (PCOS – a syndrome characterized by sparse ovulation, hyperandrogenemia, and obesity as the main clinical features). Most of the PCOS patients are overweight or obese, appropriate reduction of body weight in PCOS patients (about 5% to 10% of body weight) can significantly improve the hyperandrogenism and ovulation function, while the patient’s degree of obesity significantly affects the clinical symptoms and endocrine function of PCOS patients. 4, increase the amount of ovulation drugs and complication rate Finally, the application of assisted reproductive technology for the study of female obesity provides a unique opportunity to visualize the reproductive tissues of obese women (including ovarian reserve, egg quality, sperm-egg binding, embryonic development potential, etc.), to provide direct evidence to prove that obesity affects the oocytes, embryos and endometrium, and to increase the amount of ovulation drugs and complication rate such as Ovarian Hyperstimulation Syndrome (OHSS – a medical complication caused by ovulation induction). Does obesity continue to play a role after pregnancy? 1, during pregnancy, obese women are prone to metabolic abnormalities, leading to miscarriage, obstructed labor, stillbirth, resulting in embryonic neurological developmental abnormalities; 2, prone to pregnancy complications, such as gestational diabetes mellitus, hypertension, preeclampsia, venous thrombosis, phlebitis, anemia, nephritis; 3, after cesarean section is more susceptible to post-partum hemorrhage, prolonged healing of the incision, postoperative infections, and intra-operative anesthetics are also more sensitive to obese patients’ Respiratory inhibition is also more sensitive; 4, increase the risk of macrosomia, postnatal hypoglycemia; 5, recent studies have shown that the mother of obese children born of the late stage of obesity, diabetes and cardiovascular disease risk increases. Obese women want healthy children how to do? The answer has been crying out, that is to reduce weight, then reduce how much is appropriate? Recently, the Harvard School of Public Health study showed that thin people are more likely to get pregnant than fat people, successful slimming 5KG women, on average, only 2.5 months to successfully get pregnant, half a month faster than the average person or obese people. It has also been shown that losing 5-10% of your body weight can help restore your menstrual cycle and ovulation. Our recommendation is to start preparing for pregnancy after losing 10-15% of your basal body weight through dietary control and exercise, and to strictly control your weight gain between preparation and pregnancy. Obese patients’ mantra of “drinking cold water is fat” is in fact mostly caused by wrong weight loss methods. To face the dangers of obesity, through medical means to screen the causes of obesity, the development of scientific and systematic weight loss program for patients with obesity and related complications, especially important!