Association Between Peri-Transfer Endometrial Peristalsis And Live Birth In Modified Natural Cycle Frozen Embryo Transfer: A Prospective Cohort Study

• 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.
• Uterine contraction frequency is defined as the number of peristaltic waves per minute.

The frequency of endometrial peristalsis at different time points

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.

Direction of peristalsis is categorized as cervix-to-fundus, fundus-to-cervix, indeterminate, or absent (no contractions observed)

The correlation between endometrial peristalsis at different time points.

Defined as serum human chorionic gonadotropin level ≥ 25 mIU/mL.

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.

A pregnancy diagnosed by ultrasonographic or clinical documentation of at least one fetus with a discernible heartbeat at 12 weeks gestation or beyond.

The number of gestational sacs observed divided by the number of embryos transferred (usually expressed as a percentage).

A pregnancy outside the uterine cavity, diagnosed by ultrasound, surgical visualization, or histopathology.

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.

A pregnancy with more than one embryo or fetus.

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.

Vaginal delivery, C-section (elective, suspected fetal distress, non-progressive labor).

Weight of the newborn measured right after delivery.

Calculated by gestational age of all live births.

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.

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.

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 g

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.

Birth weight less than 1.500 g.

Birth weight less than 2.500 g.

Implies growth beyond an absolute birth weight, historically 4.000 g or 4.500 g, regardless of the gestational age.

Birth weight over 4.500 g for women with diabetes, and a threshold of 5000 g for women without diabetes.

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).

The admission of the newborn to the NICU.

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.