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Natural Versus Programmed Frozen Embryo Transfer (NatPro)

Multi-center, Parallel-group, Randomized Controlled Trial of Modified Natural Versus Programmed Cycles for Frozen Embryo Transfers and Their Association With Preeclampsia and Live Births

Status
Active, not recruiting
Phases
Phase 3
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT04551807
Acronym
NatPro
Enrollment
788
Registered
2020-09-16
Start date
2020-09-16
Completion date
2026-04-01
Last updated
2025-05-16

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

Conditions

Pre-Eclampsia, Pregnancy Related

Keywords

frozen embryo transfer, infertility, in vitro fertilization

Brief summary

NatPro is a two-arm, parallel-group, multi-center, randomized trial in which women undergoing frozen embryo transfer (FET) will be randomized to receive either a modified natural cycle (corpus luteum present) or a programmed cycle (corpus luteum absent).

Detailed description

NatPro is a two-arm, parallel-group, multi-center, randomized trial in which women undergoing FET will be randomized to receive either a modified natural cycle (corpus luteum present) or a programmed cycle (corpus luteum absent). The study will implement a stratified randomization design to balance the use of pre-implantation genetic testing (PGT) across the two treatment arms. Each participant will have up to 3 FET cycles until live birth occurs, or the participant has no embryos available for transfer. Primary endpoints will be the proportion of women experiencing preeclampsia comparing modified natural to programmed FET among women with viable pregnancy (defined as pregnancy lasting at least 20 weeks) and the cumulative proportion of women having live births in the two arms.

Interventions

This treatment protocol is defined as a modified natural cycle as the participant will be instructed to (1) administer human chorionic gonadotropin (hCG) to assist with timing of the embryo transfer and (2) supplement the luteal phase with a low dose of progesterone.

PROCEDUREProgrammed cycle

This protocol is designated as programmed because the endometrial development occurs only in association with administration of estradiol and progesterone. No ovulation occurs due to suppression of follicle development by the estradiol and the timing of the transfer is based on the number of days elapsed following initiation of exogenous progesterone.

Sponsors

JHSPH Center for Clinical Trials
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
SINGLE (Outcomes Assessor)

Eligibility

Sex/Gender
FEMALE
Age
18 Years to 41 Years
Healthy volunteers
Yes

Inclusion criteria

To be eligible, subjects must meet all these criteria: * Age 18-39 years at the time that embryos were created if no PGT testing was performed. If PGT testing was performed and indicates that an embryo is euploid, the patient can be included if she was age 18-41 years at the time that the embryo was created. * Age 18-41 years at the time of randomization as advancing age itself becomes a significant risk for preeclampsia * Normal uterine cavity as assessed by saline infusion sonohysterogram, hysterosalpingogram, or hysteroscopy within one year of the enrollment visit, and repeated at the discretion of the investigator * Regular menstrual cycle length (approximately 24-35 days) indicative of ovulatory cycles. * Willing to undergo elective single embryo transfer * Body Mass Index \<=40 * If Body Mass Index is over 30 or individual has other risk factors for diabetes, normal hemoglobin A1C * Prior to enrollment, participant will have at least one vitrified blastocyst with euploid result by pre-implantation genetic testing (PGT-A) or at least one vitrified blastocyst of fair or better morphologic quality if no PGT-A results are available. * Willingness to be randomized to either a modified natural or programmed cycle, with a willingness to administer intramuscular progesterone in oil if assigned to the programmed cycle. * Normal thyroid stimulating hormone (TSH), according to local laboratory standards (or TSH level with a clinically insignificant abnormality per the site director), within one year of study enrollment and repeated at the discretion of the investigator. Use of thyroid medication is permitted.

Exclusion criteria

To be eligible, subjects must not meet any one of these criteria: * Medical contraindication to pregnancy * Embryos created using donor oocytes * Embryo donation * Gestational carrier * Reciprocal IVF (one female partner carrying pregnancy, other female partner as source of eggs) * Fresh embryos created from frozen oocytes. Patients with frozen embryos created from frozen oocytes can be included. * Recurrent implantation failure defined as no clinical pregnancy with ≥ 2 prior consecutive embryo transfers unless patient also had successful live birth between or after the failed embryo transfers * Anti-phospholipid antibody syndrome or rheumatologic disease requiring chronic systemic medications * Uncontrolled diabetes mellitus * History of \>1 pregnancy loss in the second or third trimester * Uncontrolled hypertension * Untreated hydrosalpinx (i.e., hydrosalpinx in situ which has not been ligated or removed) * Mullerian uterine anomaly, if not correctable * Physician recommendation to perform the embryo transfer outside of the timing specified by the protocol * Contraindication to any medication which must be used in preparation for the frozen embryo transfer (i.e., estradiol, progesterone, hCG)

Design outcomes

Primary

MeasureTime frameDescription
PreeclampsiaDuring pregnancy through the post-partum period, according to ACOG guidelines (typically between 20 weeks gestation and 6 weeks post-delivery)Frequency of preeclampsia, as defined by American College of Obstetricians and Gynecologists (ACOG) guidelines for hypertensive disorders in pregnancy (Obstetrics & Gynecology 2020;135:e237-e260)

Countries

United States

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 21, 2026