Endometrial peristalsis may influence embryo implantation and pregnancy outcomes, but its role during hormone replacement therapy (HRT)-prepared frozen embryo transfer (FET) cycles remains unclear. This prospective observational study will assess endometrial peristalsis at predefined time points during HRT-prepared FET cycles using transvaginal ultrasonography and evaluate its association with pregnancy outcomes. The study aims to clarify the clinical significance of endometrial peristalsis in HRT-prepared FET cycles and to provide evidence supporting endometrial assessment in assisted reproductive technology.
Frozen embryo transfer (FET) has become an integral component of assisted reproductive technology (ART), and successful implantation depends on adequate endometrial receptivity. Different endometrial preparation protocols, including natural cycles and hormone replacement therapy (HRT) cycles, create distinct hormonal environments that may influence endometrial physiology. Among these protocols, HRT is the most widely used approach because it is applicable to a broad range of patients and offers greater flexibility in treatment scheduling. Endometrial peristalsis, characterized by rhythmic contractions of the uterine junctional zone, is thought to play an important role in embryo transport and implantation. Previous studies have suggested that the frequency and direction of endometrial peristalsis are influenced by ovarian steroid hormones and may be associated with implantation and pregnancy outcomes. However, most available evidence has focused on natural menstrual cycles, while data regarding endometrial peristalsis during HRT-prepared FET cycles remain limited and inconsistent. The temporal changes in endometrial peristalsis throughout HRT endometrial preparation and their relationship with reproductive outcomes have not been fully elucidated. This prospective observational study is designed to characterize endometrial peristalsis during HRT-prepared FET cycles using transvaginal ultrasonography and to evaluate the association between endometrial peristalsis and pregnancy outcomes. Endometrial peristalsis will be assessed at predefined time points during endometrial preparation, and pregnancy outcomes will be compared according to the observed peristaltic patterns. The results of this study are expected to improve understanding of endometrial physiology during HRT-prepared FET cycles and provide evidence on the clinical significance of endometrial peristalsis for reproductive outcomes.
Study Type
OBSERVATIONAL
Enrollment
442
Time point for measurement of endometrial peristalsis will be assessed at three specific time points: * On the second day to the fourth day of the menstrual cycle in the FET cycles. * The day of progesterone initiation (before progesterone exposure) * On the day of embryo transfer, immediately prior to the procedure Hormone measurements: serum levels of estradiol (E2) and progesterone (P4) will be assessed three times, on the same days as the endometrial peristalsis measurements, using electrochemiluminescence immunoassays. (Elecsys® Estradiol III and Elecsys® Progesterone III, Cobas® e 411, Roche Diagnostics, Germany): * On the second day to the fourth day of the menstrual cycle in the FET cycles * The day of progesterone initiation * On the transfer day prior to the procedure.
IVFMD - My Duc Hospital
Ho Chi Minh City, Vietnam
RECRUITINGThe correlation between endometrial peristalsis at different time points and live birth rates
The correlation between endometrial peristalsis at different time points and live birth rates
Time frame: Up to delivery
The frequency of endometrial peristalsis at different time points
The frequency of endometrial peristalsis at different time points
Time frame: • On the second day to the fourth day of the menstrual cycle in the FET cycles. • The day of progesterone initiation (before progesterone exposure) • On the day of embryo transfer, immediately prior to the procedure
The correlation between endometrial peristalsis at different time points
The correlation between endometrial peristalsis at different time points
Time frame: • On the second day to the fourth day of the menstrual cycle in the FET cycles. • The day of progesterone initiation (before progesterone exposure) • On the day of embryo transfer, immediately prior to the procedure
Direction of peristalsis
Direction of peristalsis is categorized as cervix-to-fundus, fundus-to-cervix, indeterminate, or absent (no contractions observed)
Time frame: • On the second day to the fourth day of the menstrual cycle in the FET cycles • The day of progesterone initiation (before progesterone exposure) • On the day of embryo transfer, immediately prior to the procedure
The association between endometrial peristalsis at different time points and pregnancy rates
The association between endometrial peristalsis at different time points and pregnancy rates
Time frame: Up to delivery
Live birth rates after the one embryo transfer
Live birth was defined as the complete expulsion or extraction from a woman of a product of fertilization, after 22 completed weeks of gestational age; which, after such separation, breathes or shows any other evidence of life, such as heartbeat, 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 500 grams or more can be used if gestational age is unknown. Live births refer to the individual newborn; for example, a twin delivery represents two live births
Time frame: At delivery
Positive pregnancy test
Defined as serum human chorionic gonadotropin level ≥ 25 mIU/mL
Time frame: 10-14 days after embryo transfer
Clinical pregnancy
A pregnancy diagnosed by ultrasonographic visualization of one or more gestational sacs or definitive clinical signs of pregnancy. In addition to intra-uterine pregnancy, it includes a clinically documented ectopic pregnancy
Time frame: 4-6 weeks after embryo transfer
Ongoing pregnancy
A pregnancy diagnosed by ultrasonographic or clinical documentation of at least one fetus with a discernible heartbeat at 12 weeks gestation or beyond
Time frame: 12 weeks of gestation or beyond
Implantation rate
The number of gestational sacs observed divided by the number of embryos transferred (usually expressed as a percentage)
Time frame: At 4-6 weeks after embryo transfer
Ectopic pregnancy
A pregnancy outside the uterine cavity, diagnosed by ultrasound, surgical visualization, or histopathology
Time frame: Up to 12 weeks after embryo transfer
Miscarriage
Spontaneous loss of a clinical pregnancy before 22 completed weeks of gestational age, in which the embryo(s) or fetus(es) is/are nonviable and is/are not spontaneously absorbed or expelled from the uterus
Time frame: Up to 22 weeks of gestation
Multiple gestations
A pregnancy with more than one embryo or fetus
Time frame: At delivery
Multiple birth
The complete expulsion or extraction from a woman of more than one fetus, after 22 completed weeks of gestational age, irrespective of whether it is a live birth or stillbirth. Births refer to the individual newborn; for example, a twin delivery represents two births
Time frame: At delivery]
Mode of delivery
Vaginal delivery, C-section (elective, suspected fetal distress, non-progressive labor)
Time frame: At delivery
Birth weight
Weight of the newborn measured right after delivery
Time frame: At delivery
Gestational age at birth
Calculated by gestational age of all live births
Time frame: At delivery
Preterm birth
Defined as delivery at \<28, \<32, \<37 completed weeks. A birth that takes place after 22 weeks and before 37 completed weeks of gestational age
Time frame: At delivery
Gestational diabetes mellitus
A 75-g OGTT, with plasma glucose measurement when the patient is fasting and at 1 and 2 h, at 24-28 weeks of gestation in women not previously diagnosed with diabetes
Time frame: At 24-28 weeks of gestation
Hypertensive disorders of pregnancy
Hypertensive disorders of pregnancy: Pregnancy-induced hypertension, pre-eclampsia (early and late), eclampsia, and HELLP syndrome are defined in the American College of Obstetricians and Gynecologists (ACOG) 2020
Time frame: Up to delivery
Stillbirth
The death of a fetus before the complete expulsion or extraction from its mother after 28 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. Note: It includes deaths occurring during labor
Time frame: Up to delivery
Very low birth weight
Birth weight less than 1.500 g
Time frame: Up to delivery
Low birth weight
Birth weight less than 2.500 g
Time frame: Up to delivery
High birth weight
Implies growth beyond an absolute birth weight, historically 4.000 g or 4.500 g, regardless of the gestational age
Time frame: Up to delivery
Very high birth weight
Birth weight over 4.500 g for women with diabetes, and a threshold of 5000 g for women without diabetes
Time frame: Up to delivery]
Major congenital abnormalities
Structural, functional, and genetic anomalies that occur during pregnancy, and are identified antenatally, at birth, or later in life, and require surgical repair of a defect, or are visually evident, or life-threatening, or cause death. Any congenital anomaly will be included as follows 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)
Time frame: Up to delivery
NICU admission
The admission of the newborn to the NICU
Time frame: Up to delivery
Neonatal mortality
Death of a live-born baby within 28 days of birth. This can be divided into early neonatal mortality, if death occurs in the first seven days after birth, and late neonatal if death occurs between 8 and 28 days after delivery
Time frame: Up to delivery
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