Study participants and data collection
This prospective study was carried out at Ali Kemal Belviranlı Women's Health and Children’s Hospital, IVF Unit. Outcomes of 757 fresh ICSI cycles were reviewed between January 2012 and December 2017. Inclusion criteria were participants aged 20–44 years, body mass index (BMI) between 18 and 35 kg/m2, regular menstrual cycles, no uterine abnormalities in the ultrasound, and normal baseline hormonal levels. Participants were excluded from the study if they were >45 years, any diseases that affect the outcome of IVF/ICSI, such as hydrosalpinx and endometriosis. The ethical board approval was given from the institutional review board (2012/57). Written and oral informed agrement was given from the participants.
Data were obtained for age, BMI (kg/m2), smoking status, infertility period, cause of infertility, the baseline at day 3 for follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estradiol (E2) levels, thyroid-stimulating hormone (TSH), prolactin, antral follicle count, stimulation parameters, cycle cancellation rate, IVF-ICSI outcomes, CPR, live birth, and miscarriage rates.
Ovarian stimulation and oocyte retrieval
Controlled ovulation stimulation was negotiated using the gonadotropin-releasing hormone agonist (GnRHa) or the flexible gonadotropin-releasing hormone antagonist (GnRHant) protocol.
ET Procedure
Two senior physicians performed the ETs accompanied ultrasonographic appearance (Logiq 200 Pro, General Electric, Seoul, South Korea) using an embryo transfer catheter system. A sterile speculum was introduced to the vagina in the lithotomy position and the vagina and the cervix were cleared using sterile cotton swabs.
An embryologist loaded the embryos into a soft transfer catheter which was advanced to the ET physician who deposited the embryos approximately 10 mm from the uterine fundus under USG. The catheter was gently removed after 5 seconds. In cases of ET with external guidance, an initial catheter with inner sheath was inserted into the external cervical os, and then advanced through the cervical canal and internal os to 10 mm of the uterine fundus using USG. The internal sheath was withdrawn, and a second catheter loaded with embryos was introduced in its place and advanced to approximately 10 mm from the uterine fundus where the embryos were deposited. Difficult transfers required the use of a stylet in addition to this form of external guidance.
All catheters were immediately checked for retained embryos, blood, and the patient remained in the Trendelenburg position for about 10 minutes. Patients in whom tenaculum were excluded from the study. Luteal phase support was provided with progesterone in the form of Crinone 8% gel (Serono, Istanbul, Turkey) at a daily dose of 90 mg. Baseline parameters and IVF-ICSI outcomes were compared between the groups. Biochemical pregnancy was detected with a by hCG levels in venous blood tests performed 12-14 days after embryo transfer, and clinical pregnancy was accepted as those with a gestational sac accompanying fetal heart-beart on ultrasound examination at 4-5 weeks after embryo transfer. Live birth was defined as the birth of a live fetus after 22 weeks of gestational age. The subjects were stratified according to the maternal BMI as Group 1 (BMI<25 kg/m2; n= 394), Group 2 (25 kg/m2 < BMI <30 kg/m2; n=303), and Group 3 (BMI >25 kg/m2; n=172). Basal parameters, clinical and laboratory IVF-ICSI outcomes, and reproductive outcome parameters were compared between the groups.
Statistical analysis
The statistical analyses were performed using SPSS 15.0 for Windows (SPSS, Chicago, IL, USA). The Kolmogorov-Smirnov test was used for examining the continuous variables with normal and non-normal distributions. The one-way analysis of variance (ANOVA) for normally distributed variables and the Kruskal-Wallis test for not-normally distributed variables were used to compare groups. Categorical data were examined by Pearson’s chi-square test, and Fisher’s exact test was applied if the expected frequency was less than 5 in >20% of all cells. The continuous variables were presented as the mean±standard deviation (SD) and the categorical variables were demonstrated as the number of cases and percentages. The Bonferroni-adjustment was used to control the type I errors for all possible multiple comparisons. A p<0.05 value was established as statistically significant.