Blockeel 2012.

Methods	Parallel group study. Number of women randomized: 86 (44 in intervention group; 42 in control group). Number of withdrawals: 14 (9 in intervention group due to cyst development, protocol violation, insufficient ovarian response, did not undergo treatment, did not receive embryo transfer; 5 in control group due to insufficient ovarian response, did not receive embryo transfer). Number of women analyzed (for pregnancy outcome): 72 (35 in intervention group; 37 in control group).
Participants	Country: Belgium. Inclusion criteria: women aged ≤ 36 years, BMI 18‐29 kg/m2, underwent a first or second treatment cycle of IVF with ICSI, serum FSH on day 3 of the menstrual cycle < 12 IU/L, normal ultrasound scan regular ovulatory menstrual cycle of 21 to 35 days. Exclusion criteria: oocyte donors, women with endometriosis ≥ grade 3, endocrine or metabolic abnormalities, PCOS or previous history of poor ovarian response (defined as development of < 4 follicles in previous IVF or ICSI cycle). Mean age ± SD: intervention group: 29.2 ± 3.0 years; control group: 30.2 ± 3.0 years. Setting: assisted reproduction programme in Belgium.
Interventions	Intervention: oestradiol valerate (2 × 2 mg/day) during 6‐10 consecutive days (from cycle day 25 onwards) prior to start of rFSH stimulation so that the first day of stimulation occurred between Friday and Sunday. Control: no pretreatment; standard GnRH antagonist protocol. Both groups received rFSH (150 IU) and on day 6 of stimulation GnRH antagonist protocol (ganirelix 0.25 mg/day).
Outcomes	Primary: Number of women undergoing oocyte retrieval during weekend days. Secondary: Mean number of COCP in each treatment group. Number of oocytes. Duration of stimulation. Total cumulative dose of rFSH used. Pregnancy rate. Basal hormone serum values.
Notes	Power calculation: not reported. ITT analysis: not reported. Objective of the study was to assess the ability of oestradiol to control the oocyte retrieval of GnRH antagonist cycles prior to COS.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomization list.
Allocation concealment (selection bias)	Low risk	Consecutive sealed opaque envelopes.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Blinding not reported.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Reasons for, and proportions of, withdrawals balanced between the 2 treatment groups and data were analyzed on the basis of ITT.
Selective reporting (reporting bias)	Low risk	All prespecified outcomes reported,
Other bias	Low risk	Groups comparable at baseline,