| Background:It is well known that the increasing epidemic of obesity has become a worldwide public health problem, in addition to its association with a variety of comorbidities such as diabetes, hypertension and cardiovascular diseases, obesity could also negatively affect fertility and reproduction in women including spontaneous ovulation, obstetric and neonatal outcomes, as well as efficiency and outcomes of assisted reproductive technology (ART). Furthermore, there are increasing concerns that obesity women are facing a significant economic burden associated with higher costs of fertility treatment and pregnancy complications. It appears that obesity is closely associated with polycystic ovary syndrome, as supported by that obesity may worsen the insulin-related hyperandrogenemia and chronic anovulation. In PCOS population,30%-65% patients are overweight or obese, and the prevalence of PCOS in overweight or obese women also increases. More and more overweight/obese women especially combined with PCOS have no choice but seeking assisted reproductive technology because of impaired fecundity. However, there is still a lack of consensus regarding the association between BMI and IVF/ICSI treatment success include process (such as ovarian response to COH, oocyte and embryo quality) as well as outcome (such as pregnancy, miscarriage and live birth rates) measures.Objective:To investigate the effect of body mass index (BMI) on the ovarian response to stimulation, embryo quality and reproductive outcome among young women (<35 years) with PCOS undergoing first IVF/ICSI.Methods:A total of 1508 PCOS patients undergoing IVF/ICSI from June 2013 to March 2014 in 14 clinical sites were recruited in this study. The recruitment criteria were strictly controlled.1508 patients were divided into four BMI categories: underweight (BMI<18.5kg/m2), normal weight(18.5≤BMI<24kg/m2), overweight(24≤BMI<28kg/m2) and obese(BMI≥28kg/m2) according to China classification for BMI cut-off points recommended by Working Group of Obesity (WGOC), International Life Science Institute. Demographic characteristic, stimulation process, embryo quality, pregnancy outcome, obstetric outcome and neonatal outcome were compared among four groups, respectively.Results:1、Comparison of basal characteristics:Obese women with PCOS had increased duration of infertility, waist hip ratio, blood pressure, fasting and 2h insulin level, HOMA-IR index and triglyceride level, and decreased FSH, AMH and high-density lipoprotein level compared with that of normal weight women, differences were all statistically significant (P＜0.05).2、Comparison of parameters of treatment process:Obese women with PCOS had larger total dose of gonadotrophins, longer duration of stimulation, lower peak E2 level, less oocytes retrieved and embryos cryopreserved, lower 2PN (two pronuclei) fertilization rate and 2PN cleavage rate than that of normal weight women, differences were all statistically significant (P<0.05).3、Comparison of pregnancy outcomes:The clinical pregnancy rate and live birth rate were comparable across the four groups, although there were both decreased tendency as BMI rose. Comparison of pregnancy loss in second trimester showed statistically significance (P=0.007) with a progressive increased trend from a low of 5.7% in underweight patients to a high of 16.0% in the highest BMI categories, the statistical significance only exist in the pairwise comparison between obese group and normal weight group, however (16.0% vs 6.3%, P=0.001, adjusted α=0.0083). No significant change was observed in obstetric complications except for incidences of caesarean delivery, which was fond to be higher in the overweight group and obese group compared with the normal reference when pairwise comparison (86.3% vs 74.5%, P=0.001; 87.6% vs 74.5%, P=0.007, adjusted a=0.0083).Neonatal average birthweight and the rate of SGA differed significantly across the four group (P=0.01,0.021), further pairwise comparison showed that the underweight has the lowest average birthweight and the highest rate of SGA (32.6% vs 16.8%, P=0.008; 32.6% vs 16.2%, P=0.008; 32.6% vs 12.6%, P=0.003, adjusted a=0.0083).Conclusions:1、Obesity exacerbates the reproductive, endocrine and metabolic features of PCOS.2、PCOS women under age 35 years with high BMI had poor ovarian response following IVF/ICSI, including larger dose of gonadotropins required, longer duration of ovarian stimulation, lower peak E2 level and less number of oocyte retrieved.3、High BMI may adversely affect embryo quality in PCOS women under age 35 years undergoing IVF/ICSI, the number of 2PN (two pronuclei) fertilization embryos, 2PN cleavage embryos, D3 high quality embryos and embryos cryopreserved all decreased.4、Obese women with PCOS under 35 years old had increased risk of pregnancy loss in second trimester conceived by IVF/ICSI treatment compared by the normal reference. Comparison of pregnancy rate and live birth rate showed no statistically significance, although a decreased trend along with high BMI was observed.5、For PCOS patients under 35 years old undergoing IVF/ICSI treatment, overweight and obesity increased the incidences of cesarean delivery.6、For PCOS patients under 35 years old undergoing IVF/ICSI treatment, underweight increased the incidences of small for gestational age (SGA). |
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