Follicular phase endocrine characteristics during ovarian stimulation and GnRH antagonist cotreatment for IVF: RCT comparing recFSH initiated on cycle day 2 or 5.

Abstract

Strategies involving mild ovarian stimulation protocols for in vitro fertilization (IVF) might lessen discomfort to the patient and substantially lower complication rates. The objective of the study was to compare the follicular-phase endocrine characteristics and follicular development in patients who started recombinant FSH (recFSH) on cycle day (CD) 2 or CD5 in IVF treatment, using GnRH antagonist as comedication. This was a prospective randomized controlled trial in two university centers in Belgium and The Netherlands. Seventy-six IVF/intracytoplasmic sperm injection patients were included in the study. The control group (CD2) received a standard treatment with 150 IU recFSH from CD2, whereas in the study group (CD5), stimulation was started on d 5 of the cycle. The GnRH antagonist was administered daily from CD6 onward in both treatment arms. Endocrine follicular phase profile during ovarian stimulation was measured. Follicular-phase patterns of gonadotropin and steroid concentrations were found to be comparable in both treatment groups, except for serum estradiol being significantly higher in the CD2 group on d 6 of the cycle (295.6 ± 202.5 ng/liter in the CD2 vs. 102.5 ± 47.9 ng/liter in the CD5 group; P < 0.01) and LH being significantly higher in the CD5 group on d 6 of the cycle (1.7 ± 0.7 IU/liter in the CD2 vs. 5.0 ± 2.1 IU/liter in the CD5 group; P < 0.01). With regard to follicular development, there was no difference in the numbers of small follicles (<10 mm), intermediate follicles (10-12 and > 12-14 mm) and large follicles (>14 mm) in both groups. This study shows that the administration of recFSH starting on d 2 or d 5 of the cycle in a GnRH antagonist protocol for IVF/intracytoplasmic sperm injection patients yields a comparable endocrine profile and follicular development. Future studies should focus on the design of more patient-tailored ovarian stimulation protocols.