Home › Trials › NCT04163133
Clinical trial Recruiting at 1 site Interventional Ages 18 to 42 Women only

Delaying the ovulation trigger in antagonist IVF cycles

Official title: Comparison of Regular Trigger Timing and 1-2 Days Delay of Trigger in Ovarian Stimulations by GnRH Antagonist Protocol in in Vitro Fertilization

Run by Peking University Third Hospital · NCT04163133 · Data updated 2026-11-12

This trial will test whether waiting 1–2 days before the ovulation trigger improves embryo quality for people having IVF with an antagonist protocol.

Quick facts

Study typeInterventional
Ages18 Years to 42 Years
SexWomen only
Enrollment834 (estimated)
SponsorPeking University Third Hospital
Academic / other
Locations1 site (Beijing, Beijing Municipality)
StatusRecruiting
StartedApril 1, 2020
Main results expectedMarch 31, 2027
Study endsMarch 31, 2028
Registry record updatedNovember 2, 2026
Trial IDNCT04163133 on ClinicalTrials.gov

Is this trial a fit for you?

Likely a good fit

Ideal candidates are people aged 18–41 with AFC 5–19, AMH 1.1–2.5 ng/mL, BMI 18.5–29 kg/m2, regular menstrual cycles, two ovaries, and undergoing their first or second IVF/ICSI cycle using a fixed antagonist protocol.

Probably not a fit

Patients with poor ovarian reserve, significant medical contraindications to IVF, or who fall outside the specified AMH, AFC, BMI, or age ranges are unlikely to benefit from this approach.

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

This single-center, open-label randomized controlled trial at Peking University Third Hospital will assign eligible patients 1:1 to standard trigger timing (when three follicles reach ≥17 mm) or to a trigger delayed by 1–2 days. Ovarian stimulation uses a fixed antagonist protocol with oocyte retrieval performed 36–38 hours after trigger, followed by IVF/ICSI, standard embryo culture, and planned day-3 single or double transfer. The primary outcome is the number of good-quality embryos, with secondary outcomes including cumulative live birth rate and routine IVF safety and efficiency measures. All participant data and outcomes will be recorded in case report forms and analyzed according to the prespecified protocol.

Why it matters

Potential benefit: If successful, delaying the trigger by 1–2 days could increase the number of good-quality embryos and potentially improve cumulative live birth rates.

How similar studies have gone: Some observational work suggests antagonist timing can affect oocyte maturation and endometrial receptivity, but randomized evidence specifically testing a 1–2 day trigger delay is limited.

Who can join: the full rules

Show full inclusion / exclusion criteria 
Inclusion Criteria:

* Age: ≥18 and \<42 years old
* AFC: ≥5 and \<20
* AMH: ≥1.1 ng/mL and \<2.5 ng/mL
* BMI: ≥18.5 Kg/m2 and \<29 Kg/m2
* Regular menstrual cycles (between 22 and 35 days)
* Two ovaries present
* Planned for single or double day 3 transfer
* Infertile couples scheduled for their first or second IVF/ICSI cycle using a fixed antagonist protocol.
* Informed consent obtained.

Exclusion Criteria:

* Women with contraindication for IVF or ICSI, such as poorly controlled type 1 or type 2 diabetes mellitus; undiagnosed liver disease or dysfunction (based on serum liver enzyme test results); renal disease or abnormal serum renal function; significant anemia; history of deep venous thrombosis, pulmonary embolus or cerebrovascular accident; uncontrolled hypertension or known symptomatic heart disease; history of (or suspected) cervical carcinoma, endometrial carcinoma or breast carcinoma; and undiagnosed vaginal bleeding.
* Previous history of poor ovarian response (\<4 oocytes retrieved) with a maximal dose of OS (≥300 IU/day) or OHSS, regardless of gonadotropin dose
* Known reasons for impaired implantation (i.e. hydrosalpinx, fibroid distorting the endometrial cavity, Asherman's syndrome, thrombophilia or endometrial tuberculosis)
* Repeated miscarriages (\>2 previous biochemical pregnancies or \>2 spontaneous miscarriages)
* Recurrent implantation failure (\>3 failed cycles with good quality embryos)
* PCOS
* Untreated thyroid disfunction
* Administration of exogenous E2, P4 or gonadotropins in the preceding menstrual cycle
* Active female smoking
* Ongoing pregnancy
* Women who have previously enrolled in the trial
* Those unable to comprehend the investigational nature of the proposed study
* Women who must receive donor eggs.
* Preimplantation genetic testing (PGT) cycle.

Where it's running

  • Peking Univesity Third Hospital
    Beijing, Beijing Municipality, China     Recruiting

Study contacts

Similar studies

Other studies for the same condition or treatment. Recruiting studies are listed first.

How to take part

  1. Review the eligibility criteria above with your treating physician.
  2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
  3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov ↗ Find more trials like this →
Browse more
IVF Outcome 2Peking University Third Hospital 93
Last reviewed 2026-11-14 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.