Risk factors for placenta accreta spectrum in pregnancies conceived after frozen-thawed embryo transfer in a hormone replacement cycle.

OBJECTIVE: Assisted reproductive technology (ART), especially frozen-thawed embryo transfer (FET) in a hormone replacement cycle (HRC), is a risk factor for placenta accreta spectrum (PAS). This study aimed to clarify the risk factors for PAS related to the maternal background and ART techniques in pregnancies achieved after FET in an HRC. STUDY DESIGN: We performed a case-control study in two tertiary perinatal centres in Japan. Among 14,028 patients who delivered at ≥24 weeks of gestation or were transferred after delivery to two tertiary perinatal centres between 2010 and 2021, 972 conceived with ART and 13,056 conceived without ART. PAS was diagnosed on the basis of the FIGO classification for the clinical diagnosis of PAS or retained products of conception after delivery at ≥24 weeks of gestation. We excluded women with fresh embryo transfer, FET with a spontaneous ovulatory cycle, a donor oocyte cycle, and missing details of the ART treatment. Finally, among women who conceived after FET in an HRC, 62 with PAS and 340 without PAS were included in this study. Multivariate logistic regression models were used for case-control comparisons, with adjustment for maternal age at delivery, parity, endometriosis or adenomyosis, the number of previous uterine surgeries of caesarean section, myomectomy, endometrial polypectomy or endometrial curettage, placenta previa, the stage of transferred embryos, and endometrial thickness at the initiation of progestin administration. RESULTS: PAS was associated with ≥2 previous uterine surgeries (adjusted odds ratio, 3.57; 95 % confidence interval, 1.60-7.97) and the stage of embryo transfer (blastocysts: adjusted odds ratio, 2.89; 95 % confidence interval, 1.15-7.26). In patients with <2 previous uterine surgeries, PAS was associated with an endometrial thickness of <7.0 mm (adjusted odds ratio, 5.18; 95 % confidence interval, 1.10-24.44). CONCLUSION: Multiple uterine surgeries and the transfer of blastocysts are risk factors for PAS in pregnancies conceived after FET in an HRC. In women with <2 previous uterine surgeries, a thin endometrium before FET is also a risk factor for PAS in these pregnancies.

Vitrification of oocytes, embryos and blastocysts.

In assisted reproductive technology, cryopreservation of human oocytes and embryos has been significantly improved by refined slow-cooling and the new vitrification method. The slow-cooling method requires a programmed cryo-machine, and usually takes several hours. It is, however, difficult to eliminate injuries resulting from ice formation completely. Vitrification has become a reliable strategy because it is simple, can lead to high survival rates and viability, and has better clinical outcome. Vitrification transforms cells into an amorphous glassy state inside and outside the vitrified cell with ultra-rapid cooling and warming steps by plunging the oocytes and embryos into liquid nitrogen, instead of ice-crystal formation. Over the past decade, several advances in vitrification technologies have improved clinical efficiency and outcome. In this chapter, we focus on vitrification technologies for cryopreservation in human assisted reproductive technology.

Perinatal outcome of blastocyst transfer with vitrification using cryoloop: a 4-year follow-up study.

OBJECTIVE: To evaluate perinatal outcome of ultrarapid vitrified blastocyst transfer. DESIGN: Retrospective study. SETTING: Private IVF clinics. PATIENT(S): One hundred eight women, who delivered 147 babies. INTERVENTION(S): Supernumerary blastocysts were vitrified using cryoloop method and transferred after warming. MAIN OUTCOME MEASURE(S): Survival rate of blastocyst after vitrification, implantation and pregnancy rates, neonatal outcome and congenital birth defects. RESULT(S): A total of 1,129 vitrified blastocysts from 435 cycles were warmed and 967 survived (85.7%). In 413 cycles of transfer, the pregnancy, implantation, and abortion rates were 44.1%, 29.0%, and 22.0%, respectively. Of 108 deliveries, 34 (32.9%) were multiple pregnancies and 20 were preterm (18.5%). Out of 147 children born, 50.3% were male and congenital birth defects were observed in 1.4%. These results were similar with those of fresh blastocyst transfer program. CONCLUSION(S): The vitrification of blastocyst using cryoloop is a simple, easy, and quick method. This technique yields the same high pregnancy and implantation rates as fresh blastocyst transfer. Congenital defect rate in this study was similar to fresh blastocyst transfer, proving the method to be safe.

GnRH antagonist improved blastocyst quality and pregnancy outcome after multiple failures of IVF/ICSI-ET with a GnRH agonist protocol.

BACKGROUND: To determine the efficacy of a gonadotrophin-releasing hormone (GnRH) antagonist, cetrorelix, in improving the quality of embryos and pregnancy outcome, we performed a study in patients with a history of multiple failures of in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) cycles with a GnRH agonist (GnRHa) long protocol. METHODS: Forty women with no live births after conventional IVF or ICSI embryo transfer (ET) and subsequent blastocyst transfer (BT) with a GnRHa long protocol entered this study. The treatment protocol consisted of a daily dose of clomiphene citrate 100 mg for 5 days and gonadotrophin injections daily from cycle day 4 onward. Cetrorelix, 0.25 mg/day, was started when the leading follicle reached 14 mm. Induction of ovulation was triggered with human chorionic gonadotrophin (HCG) (N = 36) or GnRHa (N = 4). It was possible to perform BT in 38 patients. RESULTS: Comparison of the results with the results for BT with the previous GnRHa protocol showed no significant differences in number of oocytes retrieved or the zygote- and blastocyst-development rate. With the cetrorelix protocol, however, number of patients whose embryos had developed to at least one expanded blastocyst on day 5 was significantly higher than with the GnRHa protocol (25 vs. 9) (p < 0.001), and 16 of the women became pregnant (42.1%), with 7 delivering 9 infants, 4 ending in abortion (25%), and 5 in progressing. CONCLUSIONS: The use of a GnRH antagonist in controlled ovarian hyperstimulation improves the outcome of pregnancy of patients with a history of multiple failure of IVF/ICSI-ET in a GnRHa protocol, most likely due to improvement of the quality of the blastocysts generated.