Uterine factors modify the association between embryo transfer depth and clinical pregnancy

Abstract

The embryo transfer depth may affect the chance of pregnancy. However, embryo dislodging caused by uterine contraction may occur after the transfer. The aim of the retrospective study was to investigate whether the factors associated with uterine contractilities, such as endometrial thickness and progesterone elevation, affect the association between transfer depth and implantation. A total of 7849 fresh transfer cycles on conventional stimulation in a single in vitro fertilization (IVF) center during the period 2013–2015 was reviewed. Patients were categorized according to quartiles of embryo transfer depth (≤ 9 mm, n = 1735, 9.1–11 mm, n = 2557, 11.1–14 mm, n = 1933, ≥ 1.4 mm, n = 1624, respectively). Adjusted for confounding factors, the adjusted odds ratio (aOR) (95% confidence interval, CI) for clinical pregnancy was 0.90 (0.79–1.02), 0.86 (0.74–0.99), and 0.70 (0.60–0.82) respectively in quartiles 2 through 4, comparing with quartile 1. However, the aORs were significantly increased when the endometrial thickness was < 8 mm. In comparison with that in the cycles with a normal endometrial thickness (8–11 mm), the aORs comparing quartiles 2 through 4 with quartile 1 in the cycles with an endometrial thickness < 8 mm increased from 0.78 (95% CI 0.65–0.93), 0.79 (95% CI 0.65–0.97), and 0.64 (95% CI 0.51–0.81) to 1.73 (95% CI 1.21–2.47), 1.04 (95% CI 0.69–1.56), and 1.45 (95% CI 0.91–2.31), respectively. In the cycles with elevated progesterone and blastocyst stage transfer, the aORs comparing quartiles 4 with quartile 1 decreased from 0.73 (95% CI 0.62–0.87) and 0.74 (95% CI 0.63–0.87) to 0.58 (95% CI 0.40–0.84) and 0.42 (95% CI 0.25–0.73) than those in the cycles without. However, only blastocyst transfer showed a significant interaction with transfer depth (p = 0.043). Our data suggested that endometrial thickness and blastocyst transfer significantly affect the association between embryo transfer depth and clinical pregnancy.

The impact of transferred air bubble position on clinical pregnancy rate in FET cycles

“…However, some previous studies did not conduct a multivariate logistic regression analysis, which maybe another reason explained the contradictory conclusions. The finding in this study is consistent with that of Sun et al , who observed that only blastocyst transfer showed a significant interaction with transfer depth ( Sun et al 2022 ). As embryo implantation occurs 6–7 days after fertilization, and previous studies have found that the transferred embryo swims in the uterine cavity, though it was only observed for 60 min after transfer ( Saravelos et al 2016 , Fıçıcıoğlu et al 2018 ), we hypothesized that implantation will occur within 24–36 h after blastocyst transfer, while the cleavage embryo will still whirl around and relocate for 72–96 h before implantation.…”

Interstitial ectopic pregnancy (Clinical case)

“…Установлено, що збільшити ризик позаматкової вагітності може підсадка ембріона на стадії розщеплення, ніж на стадії бластоцисти [2,12]. Деякі автори вивчають технічні проблеми процедур допоміжних репродуктивних технологій [14,17,18]. Як кожен фактор впливає на ризик виникнення позаматкової вагітності після допоміжних репродуктивних технологій, невідомо та потребує подальшого дослідження.…”