INTRODUCTION
The overweight and obesity epidemic continues to plague modern society due to the radical change of lifestyle and decreased physical exercise in recent years. Research has demonstrated that overweight and obesity are major causes of chronic diseases, such as cardiovascular disease and type 2 diabetes1. Obesity raises the risk of hypertension, dyslipidemia, diabetes, and coronary heart disease.
The burden of overweight and obesity is high in both developed and developing countries, with the proportion of overweight and obese women increasing from 29.8% in 1980 to 38.0% in 20132. Elevated body mass index (BMI) in women affects every stage of reproductive life, including puberty, pregnancy, and delivery. This is related to menstrual and ovulatory disorders, impaired endometrial development and embryo implantation, increased abortion rates, and pregnancy complications, such as hypertensive disorders of pregnancy (HDP), pre-eclampsia, gestational diabetes mellitus (GDM), postpartum hemorrhage, and cesarean delivery3. Moreover, adverse perinatal outcomes, including fetal macrosomia and neural tube defects, are more likely to occur in obese women4.
Numerous studies investigating the impact of elevated BMI on in-vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) outcomes have been published, albeit with disparate results. Several studies found that an elevated BMI had no adverse effect on IVF/ICSI outcomes5-8, while others demonstrated that elevated BMI was associated with adverse IVF outcomes, including lower ovarian response, inferior oocyte and embryo quality, higher cancellation rate, and lower clinical pregnancy rate (CPR) and LBR, as well as higher rate of miscarriages9-16. Despite the broad research in this area, the effect of elevated BMI on IVF/ICSI outcomes is indeterminate.
Therefore, the aim of this study was to evaluate the impact of elevated BMI on both short- and long-term outcomes of fresh IVF/ICSI cycles and subsequent frozen embryo transfer (FET) cycles, particularly ovarian response, embryo quality, pregnancy outcomes, obstetric and neonatal complications, and congenital defects. This way, the impact of high BMI on assisted reproductive technology (ART) can be elucidated more comprehensively and inform pre-ART counseling of overweight and obese women.