A spontaneous miscarriage was defined as a spontaneous pregnancy loss after sonographic visualization of an intrauterine gestational sac. A clinical pregnancy was defined by at least one gestational sac found on the ultrasonography 4—6 weeks after an embryo transfer. An ectopic pregnancy and spontaneous miscarriage were all considered as clinical pregnancies.
A miscarriage that occurred before gestational Week 12 was defined as an early miscarriage. A live birth was defined as one or more live babies delivered after 28 weeks of gestation. The primary outcome included the live birth rate, gestational week at the delivery and newborn birth weight. The secondary cycle outcomes included the implantation rate, clinical pregnancy rate, early miscarriage rate, and ectopic pregnancy rate.
Statistical analysis was performed using the Empower Stats software base on R language. Smooth curve fitting was performed to assess if there was any non-linear relationship between endometrial thickness and pregnancy outcomes. Then a segmented regression model was used to analyze the threshold effect between endometrial thickness and pregnancy outcomes. All patients were grouped according to their endometrial thickness on the ET day.
Patient demographics and characteristics are shown in Table 1. There were significant differences between the age, infertility duration, BMI and percentage of primary infertility of the women in each group, but there was no difference in the number and type of embryos transferred. Table 1. In order to control the impact of age, the duration of infertility, BMI and the infertility type primary or secondary on pregnancy outcomes, we performed multivariable logistic regression analysis to evaluate the association between endometrial thickness and pregnancy outcomes.
After making adjustments based on the above factors, significant associations were found between endometrial thickness and implantation rate adjusted odds ratio [aOR]: 1. The associations between endometrial thickness and early miscarriage rate, ectopic pregnancy rate, gestational weeks at delivery and newborn birth weight were not significant Table 3.
All adjusted for age, the duration of infertility, body mass index, infertility type, and the number type of embryos transferred. For continuous variables such as endometrial thickness, the implantation rate, clinical pregnancy rate and live birth rate, the fitted curves are presented in Figs 1 — 3 , respectively. With the increase of endometrial thickness, the implantation rate, clinical pregnancy rate and live birth rate initially went up and then down Figs 1 — 3.
The solid-dotted red line represents the smooth curve that fits between variables. All were adjusted for age, the duration of infertility, body mass index, infertility type, and the number and type of embryos transferred. The threshold effect analysis of endometrial thickness and the implantation rate, clinical pregnancy rate and live birth rate are presented in Table 4.
The endometrial thickness is a non-linear significant predictor of clinical outcomes, and its turning point is 8. Between the endometrial thickness on the transfer day compared with the thickness at the starting of progesterone day, endometrial thickness had no changed cycles, the increased and compaction cycles accounted for Endometrial receptivity is the key factor affecting the pregnancy outcomes of embryo transfer cycles [ 9 ].
It has the advantage of: being non-invasive, simplicity, convenience, cost-effectiveness, repeatability as well as other advantages. Using transvaginal ultrasonography to measure endometrial thickness is often used to help assess the timing of endometrial transformation and the endometrial receptivity [ 9 , 10 ].
However, there is no consensus on the relationship between endometrial thickness and pregnancy outcomes. The endometrial thickness was measured at different time points during previous studies, such as on the day of hCG administration, on the day of oocyte retrieval or on the day embryos transferred [ 11 — 14 ].
In addition to this, the published studies also varied in other factors, for example, controlled ovarian stimulation protocols, FET protocols, number of embryos transferred, and the type of embryo transferred cleavage stage embryo or blastocyst [ 14 — 17 ]. Many factors could affect endometrial receptivity in fresh IVF cycles and natural cycle FETs, such as excessive estrogen levels, elevated endogenous progesterone, and LH surge.
Since such factors can be confounding and affect the reliability of the study results, the relationship between endometrial thickness and IVF outcomes has been a subject of much debate for several decades. Recently, a meta-analysis including 22 studies concluded that there seems to be no justification for using to use endometrial thickness as a tool to help people decide on cycle cancellation, freeze-all or refraining from further IVF treatment [ 18 ].
Another meta-analysis that included 4, cycles from 14 studies was not able to draw a convincing conclusion on the relationship between endometrial thickness and the pregnancy rate in IVF [ 19 ]. As far as we know, previous studies only focused on whether endometrial thickness affects clinical outcomes or not. The study of K. Liu et al. As with most of the previous studies, in the study of Zhiqin Bu et al. Patients who had thin endometrial thickness in Group A had significantly lower rates in clinical pregnancy and live birth than those in Group B or C [ 9 ].
In our study, we found significant associations between endometrial thickness and the rates of implantation aOR: 1. The curve fitting analysis further revealed a quantitative relationship between endometrial thickness and clinical outcomes. The cut-off value of the endometrial thickness was 8. With every millimeter increment of endometrial thickness up to 8. It is noteworthy that this study is the first to report a minimum threshold of endometrial thickness for optimal pregnancy outcomes.
Several studies in the past merely reported a relatively broad range of endometrial thicknesses that were considered optimal for pregnancy outcomes while the classification of endometrial thickness in their studies was arbitrary, being mainly based on clinical experience or references [ 5 , 9 , 14 ], while the range of endometrial thickness in each group was also very large, thus making these studies unlikely of being able to provide good guidance for clinical practice.
The result of threshold effect analysis showed that 8. Thank you for subscribing! Follow Us :. Causes and Treatment. Follow Us. Facebook Twitter Pinterest Email. Leave your review Cancel reply 1 2 3 4 5. Subscribe Now. These and other adjuvant therapies have been used in an attempt to improve endometrial receptivity for patients. Unfortunately, to date no one single therapy has been proven to be effective for all patients.
Providers must evaluate each patient individually and use their best judgement as to which adjuvant therapy may benefit that specific patient. Blog Toggle navigation. Endometrial receptivity and Endometrial Thickness are crucial during IVF Cycles The endometrium or uterine lining is important to reproduction since the embryo must implant into the endometrium of the uterus to initiate a pregnancy.
Back to blog home. April 27, Dr. How to thicken uterine lining for IVF? During a normal pregnancy process, an embryo gets implanted on the lining of the uterus. This uterine lining is called endometrium, which is present inside the uterus.
Once the fertilization occurs, pregnancy happens if an embryo gets stuck or gets implanted in the endometrium. Causes of Thin Uterine Lining Thin uterine lining can cause implantation problems which in turn will prevent pregnancy, to occur.
There are some reasons behind thin lining like: Deficiency of estrogen. Low level of blood flow in the uterus. Fibroids in the uterus. Infected endometrial cells. Conclusion The process of in vitro fertilization can be stressful for a working woman who wishes to conceive. Give us a clap claps, they found this blog helpful. Share this with.
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