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NATural Ovarian Stimulation

An Innovative Controlled Ovarian Hyperstimulation (COH) Protocol That Combines Large Oocyte Availability and Physiologic Estrogenic Environment for Good Prognosis In Vitro Fertilization and Embryo Transfer (IVF-ET) Patients

Status
Completed
Phases
Phase 4
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT02892942
Acronym
NATOS
Enrollment
129
Registered
2016-09-08
Start date
2017-01-13
Completion date
2019-02-08
Last updated
2026-04-03

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Infertility

Keywords

Controlled ovarian hyperstimulation, Estradiol, Embryo implantation, Endometrial receptivity, Fertility preservation

Brief summary

To overcome unsuitable effects of controlled ovarian hyperstimulation (COH )while maintaining large oocyte availability, investigators elaborated an innovative protocol (NATural Ovarian Stimulation) that dissociates E2 production from multiple follicle development. The purpose of this prospective, randomized trial is to demonstrate that, in a good prognosis IVF-ET population, the physiological E2 environment resulting from NATOS significantly improves IVF-ET outcome when compared to the conventional GnRH antagonist protocol.

Detailed description

Controlled ovarian hyperstimulation (COH) seeks to improve IVF-ET results by increasing per-cycle oocyte and embryo availability. Yet, the coexistence of multiple preovulatory follicles engenders compulsory alterations in the endocrine milieu of the follicular phase. The most evident of them are the extremely high serum estradiol (E2) levels. The 10 to 15-fold increase in E2 levels as a result of COH has been shown to provoke unwanted consequences in both embryo quality and uterine receptivity. Therefore, investigators elaborated an innovative COH protocol (NATural Ovarian Stimulation) that aimed at dissociating E2 production from multiple follicle development. To obtain this effect, they virtually curtailed endogenous LH production by using GnRH antagonist doses as strong and frequent enough to maintain E2 levels around the physiological range during standard exogenous FSH-only administration. Given that high E2 levels are commonly reached in patients having a normal follicle endowment, NATOS should target this group of good prognosis IVF-ET candidates. Indeed, this new COH approach was first tested in a pilot study that included 15 good prognosis IVF-ET candidates, aged 25-35 years, who volunteered to undergo NATOS. 11 out of 15 patients achieved a pregnancy. These pilot results spurred them to conduct a prospective, randomized trial to demonstrate that, in a good prognosis IVF-ET population, the physiological E2 environment resulting from NATOS significantly improves IVF-ET outcome when compared to the conventional GnRH antagonist protocol.

Interventions

225 to 450 IU/d; from day 2 of menstrual cycle onward

0.25 mg/day, starting on day 6 of Gonal-F®.

Sponsors

Assistance Publique - Hôpitaux de Paris
Lead SponsorOTHER
MerckSerono Pharmaceuticals
CollaboratorUNKNOWN
URC-CIC Paris Descartes Necker Cochin
CollaboratorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE

Eligibility

Sex/Gender
FEMALE
Age
18 Years to 40 Years
Healthy volunteers
No

Inclusion criteria

* IVF-ET candidates (excluding PGD and oocyte donor); * Body mass index from 18 to 30 kg/m2; * Non smokers; * Regular menstrual cycles (25-35 days); * Presence of both ovaries; * Antral follicle count (follicles measuring from 3 to 10 mm in diameter) ranging from 10 to 30 on cycle days 2 to 4; * Serum AMH levels ranging from 0.5 to 5.0 ng/mL; * Normal endometrium at ultrasound (US) and/or hysteroscopy; * Informed consent signed

Exclusion criteria

* Iatrogenic ovarian insufficiency (surgery, radiotherapy, chemotherapy); * Uterine abnormalities as demonstrated by pelvic US and/or hysteroscopy; * Usual contra-indications for COH (cancer risk, blood coagulation disorders, etc) * Renal insufficiency

Design outcomes

Primary

MeasureTime frameDescription
Live birth obtained after IVF-ET1 month post-partumLive birth defined as delivery ≥ 22 weeks of amenorrhea

Secondary

MeasureTime frame
Number of oocytes obtainedAt oocyte retrieval (14±8 days after start of treatment)

Countries

France

Contacts

PRINCIPAL_INVESTIGATORRENATO FANCHIN, MD, PhD

Assistance Publique - Hôpitaux de Paris

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Apr 4, 2026