Skip to content

Natural Cycle vs. Modified Natural Cycle vs. Artificial Cycle Protocol for Endometrial Preparation.

The Effectiveness and Safety of the Three Endometrial Preparation Protocols for Frozen Embryo Transfer Natural Cycle, Modified Natural Cycle and Artificial Cycle: a Randomized Controlled Trial

Status
Completed
Phases
NA
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT04804020
Acronym
MONART
Enrollment
1428
Registered
2021-03-18
Start date
2021-03-22
Completion date
2023-12-31
Last updated
2024-07-29

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

Conditions

IVF, Frozen Embryo Transfer

Brief summary

Fresh embryo transfer is a routine procedure in vitro fertilization (IVF) treatment. Since the first live birth after an IVF-FET (frozen embryo transfer), recent years have seen a dramatic rise in the number of FET cycles. Three endometrial preparation protocols for frozen-thawed embryo transfer, including artificial, natural, modified natural protocol, have been studied and applied to maximize treatment outcomes. However, those methods are being applied empirically as their efficacy and safety are yet to be determined. The objective of this study is to compare the effectiveness and safety of those protocols.

Detailed description

This trial will be conducted at My Duc Hospital, Ho Chi Minh City, Viet Nam. Women who are potentially eligible will be provided information about the trial as long as their stimulation cycles are initiated. Screening for eligibility will be performed by treating physicians on day 2 of the menstrual cycle in the subsequent frozen embryo transfer cycles. Patients will be provided a copy of the informed consent documents. Written informed consent will be obtained by the investigator from all women before the enrolment. Women will be randomized (1:1:1) to AC (artificial cycle) or NC (natural cycle), or mNC (modified natural cycle) protocols using block randomization with a variable block size of 6 or 9 by an independent study coordinator via telephone, using a computer-generated random list (block size of 6, or 9). Artificial protocol The endometrium is prepared using oral estradiol valerate (Valiera®; Laboratories Recalcine) 8 mg/day, ranging from the second or fourth menstruation day. The endometrial thickness will be monitored from day six onwards, and vaginal progesterone (Utrogestan®; Besins) 800 mg/day will be initiated when endometrial thickness reaches ≥7 mm. Estradiol exposure must be lasting for ≥9 days before progesterone administration. Embryo transfer will be scheduled by the time of the initiation of progesterone and embryo stages. In cases where a dominant follicle emerged, serum LH and progesterone will be determined to rule out luteinization. If LH concentrations are \<13 IU and progesterone levels \<15 nmol/l, luteinization will deem not to have occurred, and FET was performed. Natural protocol The first ultrasound scan will be performed on the second to the fourth day of the menstrual cycle to identify any problem related to the patient's uterus or adnexa. The second ultrasound will be performed on the sixth day of the cycle. Daily ultrasound and serum estradiol and LH level evaluation will be performed when the mean diameter of the dominant follicle of ≥14 mm. LH surge initiation is defined as a concentration of 180% above the latest serum value available in that patient with a continued rise thereafter to a level of 20 IU/l or more detected by the ECLIA method (Roche Cobas® E 801, Roche Diagnostics, Germany). Embryo transfer will be scheduled by the time of the initiation of LH and embryo stages. modified Natural protocol The first ultrasound scan will be performed on the second to the fourth day of the menstrual cycle to identify any problem related to the patient's uterus or adnexa. A second ultrasound scan will be performed on the sixth day of the cycle; if there is at least one follicle with a diameter of ≥12 mm, an ultrasound scan will be performed daily. When the dominant follicle's mean diameter is ≥16 mm, human chorionic gonadotropin - hCG (Ovitrelle® 250 μg; Merck, Kenilworth, NJ, USA) will be injected to trigger ovulation. Embryo transfer will be scheduled by the time of the hCG injection and embryo stages. Serum progesterone level was also evaluated using the electrochemiluminescence immunoassay (Elecssys Progesterone III, Cobas®, Roche diagnosis, Germany) with a CV of 5.2%. Serum progesterone was measured at 3 time points: * 1st sample: On day 2 to day 4 of the cycle, before starting the endometrial preparation regime * 2nd sample: * For AC protocol: Before administration of vaginal progesterone * For mNC protocol: Before hCG administration * For NC protocol: When an LH surge initiation was recorded, i.e., serum LH measured 20 IU/L or more * 3rd sample: On the day of frozen embryo transfer at 8 a.m. Cycle cancellation * Artificial protocol: When the endometrial thickness is below 7mm after a duration of estradiol administration of ≥21 days or the emergence of a dominant follicle. * Natural cycle protocol: When there is no development of follicle, or no dominant follicle (≥14 mm), or no onset of LH surge observed after a duration of ≥21 days or unexpected spontaneous ovulation appears. * modified Natural cycle protocol: When there is no developing follicle (\>16mm) observed after a duration of ≥21 days or pre-hCG unexpected spontaneous ovulation appears. * Both protocols: When there is no embryo surviving after thawing. Frozen embryo transfer: A maximum of 2 day-3 and one day-5 embryos will be thawed on the day of embryo transfer, three days after the start of progesterone. Two hours after thawing, surviving embryos will be transferred into the uterus under ultrasound guidance using a soft uterine catheter (Gynétics®, Belgium). A series of progesterone levels evaluation will be performed at three times: (1) at the start of the cycle, (2) Before the time the embryo transfer is scheduled, (3) On the day of embryo transfer. The blood sample at the start of the cycle will be stored for further epigenetics analysis. Future babies' health will also be performed separately.

Interventions

PROCEDURENC

The first ultrasound scan will be performed on the second to the fourth day of the menstrual cycle to identify any problem related to the patients' uterus or adnexa. The second ultrasound will be performed on the sixth day of the cycle. Daily ultrasound and serum estradiol and LH level evaluation will be performed when the mean diameter of the dominant follicle of ≥14 mm. LH surge initiation is defined as a concentration of 180% above the latest serum value available in that patient with a continued rise thereafter9 to a level of 20 IU/l or more10 detected by the ECLIA method (Roche Cobas® E 801, Roche Diagnostics, Germany). Embryo transfer will be scheduled by the time of the initiation of LH and embryo stages.

PROCEDUREmNC

The first ultrasound scan will be performed on the second to the fourth day of the menstrual cycle to identify any problem related to patients' uterus or adnexa. A second ultrasound scan will be performed on the sixth day of the cycle; if there is at least one follicle with a diameter of ≥12 mm, an ultrasound scan will be performed daily. When the dominant follicle's mean diameter is ≥16 mm, human chorionic gonadotropin (Ovitrelle® 250 μg; Merck, Kenilworth, NJ, USA) will be injected to trigger ovulation. Embryo transfer will be scheduled by the time of the hCG injection and embryo stages.

PROCEDUREAC

The endometrium is prepared using oral estradiol valerate (Valiera®; Laboratories Recalcine) 8 mg/day, ranging from the second or fourth menstruation day. The endometrial thickness will be monitored from day six onwards, and vaginal progesterone (Utrogestan®; Besins) 800 mg/day will be initiated when endometrial thickness reaches ≥7 mm. Estradiol exposure must be lasting for ≥9 days before progesterone administration. Embryo transfer will be scheduled by the time of the initiation of progesterone and embryo stages.

Sponsors

University of Medicine and Pharmacy at Ho Chi Minh City
CollaboratorOTHER
Mỹ Đức Hospital
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE

Eligibility

Sex/Gender
FEMALE
Age
18 Years to 45 Years
Healthy volunteers
No

Inclusion criteria

* Aged of 18 to 45 * Having menstrual cycle duration of 24 to 38 days * Undergoing no more than 3 previous IVF/ICSI - FET cycles * Planning a frozen-thawed embryo transfer * Agreeing to have no more than 2 day 3 and 1 day 5 embryos transferred * Not participating in another IVF study at the same time

Exclusion criteria

* Menopausal/ Anovulatory women * Having contraindication for exogenous hormones administration: breast cancer, risks of venous thromboembolism * Having embryos from in vitro Maturation or oocyte donation or PGT (pre-implantation genetics testings) cycles * Having uterine abnormalities (e.g., adenomyosis, intrauterine adhesions, unicornuate/ bicornuate/ arcuate uterus; unremoved hydrosalpinx, endometrial polyp)

Design outcomes

Primary

MeasureTime frameDescription
Live birth rate after one frozen embryo transfer cycleAt 24 weeks of gestationLive birth is defined as the complete expulsion or extraction from a woman of a product of fertilisation, after 24 completed weeks of gestational age; which, after such separation, breathes or shows any other evidence of life, such as heart beat, umbilical cord pulsation or definite movement of voluntary muscles, irrespective of whether the umbilical cord has been cut or the placenta is attached. A birth weight of 350 grams or more can be used if gestational age is unknown (twins are a single count).

Secondary

MeasureTime frameDescription
Clinical pregnancyAt 5 weeks after embryo placementHaving at least one gestational sac on ultrasound at 7 weeks' gestation with the detection of heart beat activity
Ongoing pregnancyAt 10 weeks after embryo placementHaving at least 1 gestational sac on ultrasound at 12 weeks' gestation with heart beat activity
ImplantationAt 3 weeks after embryo placementImplantation rate is explained as the number of gestational sacs per number of embryos transferred.
Ectopic pregnancyAt 12 weeks of gestationA pregnancy outside the uterine cavity, diagnosed by ultrasound, surgical visualisation, or histopathology
MiscarriageAt 20 weeks of gestationThe spontaneous loss of an intra-uterine pregnancy prior to or at 20 completed weeks of gestational age
Preterm deliveryAt 22, 28, 32 weeks and 37 weeks of gestationMultiple definitions, defined as delivery at \<24, \<28, \<32, \<37 completed weeks
Endometrial preparation cycles cancelationAt 3 weeks from the start of treatment cycleCycle cancelling due to: * Artificial protocol: When the endometrial thickness is below 7mm after a duration of estradiol administration of ≥21 days or the emergence of a dominant follicle. * Natural cycle protocol: When there is no development of follicle, or no dominant follicle (≥14 mm), or no onset of LH surge observed after a duration of ≥21 days or unexpected spontaneous ovulation appears. * modified Natural cycle protocol: When there is no developing follicle (\>16mm) observed after a duration of ≥21 days or pre-hCG unexpected spontaneous ovulation appears. * Both protocols: When there is no embryo surviving after thawing. * Fluid in uterine cavity * Side effects of taking exogenous hormones: severe migraine/headache, mood swings, vaginal bleeding, nausea; venous thromboembolism, stroke. * Patient preferences
Gestational diabetes mellitusAt 24 to 28 weeks of gestationusing a 75g oral glucose tolerance test
Hypertensive disorders of pregnancyAt 20 weeks of gestation or beyondPregnancy-induced hypertension, pre-eclampsia and eclampsia
Birth weightAt the time of deliveryWeight of singletons and twins
Positive pregnancy testAt 2 weeks after embryo placementSerum ß-hCG ≥25mIU/mL
Very low birth weightAt birthWeight \< 1500 gm at birth
High birth weightAt birthWeight \>4000 gm at birth
Very high birth weightAt birthWeight \>4500 gm at birth
Major congenital abnormalitiesAt birthStructural, functional, and genetic anomalies, that occur during pregnancy, and identified antenatally, at birth, or later in life, and require surgical repair of a defect, or are visually evident, or are life-threatening, or cause death. Any congenital anomaly will be included as followed definition of congenital abnormalities in Surveillance of Congenital Anomalies by Division of Birth Defects and Developmental Disabilities, NCBDDD, Centers for Disease Control and Prevention (2020).
Admission to NICUAt birthThe admittance of the newborn to NICU
Venous thromboembolism relating to medicationFrom the start of treatment up to 10 weeks of gestationVenous thromboembolism is diagnosed after clinical examination, ultrasound scan and blood test
Multiple pregnancyAt 6 to 8 weeks' gestation≥1 gestational sac at early pregnancy ultrasound
Multiple deliveryAt 24 weeks' gestationBirth of more than one baby beyond 24 weeks
Cost-effectivenessTwo year after randomizationIncluding direct and indirect costs; costs related to complications treatment. Cost data will be collected for a supplementary analysis and will be reported in a separated paper.
Still birthAt 20 weeks' gestationThe death of a fetus prior to the complete expulsion or extraction from its mother after 20 completed weeks of gestational age. The death is determined by the fact that, after such separation, the fetus does not breathe or show any other evidence of life, such as heartbeat, umbilical cord pulsation, or definite movement of voluntary muscles.
Low birth weightAt birthWeight \< 2500 gm at birth

Countries

Vietnam

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 7, 2026