Time of implantation of the conceptus and loss of pregnancy.
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BACKGROUND: Implantation of the conceptus is a key step in pregnancy, but little is known about the time of implantation or the relation between the time of implantation and the outcome of pregnancy. METHODS: We collected daily urine samples for up to six months from 221 women attempting to conceive after ceasing to use contraception. Ovulation was identified on the basis of the ratio of urinary estrogen metabolites to progesterone metabolites, which changes rapidly with luteinization of the ovarian follicle. The time of implantation was defined by the appearance of chorionic gonadotropin in maternal urine. RESULTS: There were 199 conceptions, for 95 percent of which (189) we had sufficient data for analysis. Of these 189 pregnancies, 141 (75 percent) lasted at least six weeks past the last menstrual period, and the remaining 48 pregnancies (25 percent) ended in early loss. Among the pregnancies that lasted six weeks or more, the first appearance of chorionic gonadotropin occurred 6 to 12 days after ovulation; 118 women (84 percent) had implantation on day 8, 9, or 10. The risk of early pregnancy loss increased with later implantation (P<0.001). Among the 102 conceptuses that implanted by the ninth day, 13 percent ended in early loss. This proportion rose to 26 percent with implantation on day 10, to 52 percent on day 11, and to 82 percent after day 11. CONCLUSIONS: In most successful human pregnancies, the conceptus implants 8 to 10 days after ovulation. The risk of early pregnancy loss increases with later implantation. (+info)
Delivery rates after in-vitro fertilization following bilateral salpingectomy due to hydrosalpinges: a case control study.
(34/2169)
This retrospective case-control study assessed the impact of bilateral salpingectomy due to uni- or bilateral hydrosalpinges on the outcome of in-vitro fertilization (IVF) in a large consecutive series of patients. The effect of bilateral salpingectomy due to hydrosalpinges on pregnancy outcome was compared in 139 patients (263 cycles) and 139 age-matched controls with tubal infertility without hydrosalpinges (296 cycles). The delivery rates per initiated cycle as well as the implantation rates were equal in the two groups (21.7 versus 21.6% and 19 versus 21%). The number of embryos, the cleavage stage, and the embryo morphology score were equal in the two groups. Among 92 patients treated with 182 IVF cycles who underwent salpingectomy between 1.5 and 5 years prior to their first IVF cycle, the delivery and the implantation rates were 22.5 and 20.5% respectively. Of the patients with salpingectomy after an average of 1.7 failed IVF cycles and who re-entered the IVF programme 3 and 6 months subsequent to surgery, 47 were treated with 83 IVF cycles. The live birth and the implantation rates after surgery in this group were 20.5 and 20% respectively. It is concluded that bilateral salpingectomy due to hydrosalpinges restores a normal delivery as well as implantation rate after IVF treatment compared to controls. A favourable outcome is also found in patients operated on after repeated IVF failures. Furthermore, a normal live birth rate as well as a high implantation rate is maintained for at least three IVF cycles subsequent to surgical treatment. (+info)
Effect of 6 beta-methylprednisolone on mouse pregnancy rate.
(35/2169)
The aim of this study was to evaluate the effect of methyl-prednisolone on the pregnancy rate in mice. For this reason, zona pellucida-intact and zona pellucida-free embryos at the blastocyst stage were transferred to recipient mice at day 2.5 of pseudopregnancy. Embryo transfer was performed into non-immunodepressed and immunodepressed groups of recipient mice using 0.3 or 0.6 microgram/g of 6 beta-methylprednisolone. A higher implantation and developmental rate of zona-free embryos transferred to the immunodepressed group of recipients was observed after using the higher dose of methylprednisolone. (+info)
Apoptosis at the time of embryo implantation in mouse and rat.
(36/2169)
The aim of this review is to summarize the information currently available regarding the occurrence of apoptosis in the developing embryo and in the receptive uterus during the peri-implantation period of gestation. Cell death is detected in the inner cell mass of late pre-implantation embryos as the result of an eliminative process that helps trim the embryonic cell lineages of surplus or dysfunctional stem cells. Cell death is also detected in the epiblastic core of early post-implantation embryos, where the process is implicated in the formation of the pro-amniotic cavity. On the maternal side, uterine epithelial cells situated around the attachment site undergo cell death during the initial phase of implantation in order to facilitate embryo anchorage and access to maternal blood supply. Uterine stromal cells closest to the implantation chamber first transform into decidual cells and then commit suicide to make room for the rapidly growing embryo. Although apoptosis is well recognized as a crucial determinant of successful peri-implantation development, our understanding of the cellular and molecular mechanisms regulating this process clearly lags behind the comprehension of cell death control in other systems. (+info)
Cyclo-oxygenase-2-derived prostacyclin mediates embryo implantation in the mouse via PPARdelta.
(37/2169)
We have demonstrated previously that cyclo-oxygenase-2 (COX2), the rate-limiting enzyme in the biosynthesis of prostaglandins (PGs), is essential for blastocyst implantation and decidualization. However, the candidate PG(s) that participates in these processes and the mechanism of its action remain undefined. Using COX2-deficient mice and multiple approaches, we demonstrate herein that COX2-derived prostacyclin (PGI2) is the primary PG that is essential for implantation and decidualization. Several lines of evidence suggest that the effects of PGI2 are mediated by its activation of the nuclear hormone receptor PPARdelta, demonstrating the first reported biologic function of this receptor signaling pathway. (+info)
A study failing to determine significant benefits from assisted hatching: patients selected for advanced age, zonal thickness of embryos, and previous failed attempts.
(38/2169)
PURPOSE: Pregnancy and implantation rates after mechanical assisted hatching (AH) in patients aged > or = 38 years, with embryos > or = 15 microns in zonal thickness and two or more failed attempts, were assessed at two infertility centers using fresh and frozen embryo transfer (FET) cycles. METHODS: AH was performed on 3-day-old embryos. Spare embryos cryopreserved at the two-pronucleus stage were subjected to AH after 2 days of culture and transferred to artificially prepared uteri. RESULTS: In fresh cycles, no significant differences in pregnancy rates (clinical and ongoing) and implantation rates were observed between the AH and the controls for all three selected patient groups (Centers 1 and 2). In FET cycles, AH tended to give poor results for > or = 38 year olds (clinical pregnancy rates of 0 and 5.0% with AH vs 13.3 and 16.7% for controls at Centers 1 and 2, respectively). With AH, embryos with thick zonae implanted to the same extent as those in the control group and achieved pregnancies for patients with multiple failures (four to six attempts for some) in both fresh and FET cycles. CONCLUSIONS: AH failed to show significant benefits in all three patient groups. A larger study group may confirm the effects of AH on frozen/thawed embryos and outcomes for multiple failure cases. (+info)
A prospective comparison of 'in house' and commercially prepared Earle's balanced salt solution in human in-vitro fertilization.
(39/2169)
A prospective, randomized study was undertaken to compare the use of Earle's balanced salt solution (EBSS) prepared 'in house' with that produced commercially, in 448 cycles of therapeutic in-vitro fertilization. Outcome was assessed in terms of fertilization and cleavage rates, embryo morphology, and implantation rates following embryo transfer. The only differences that were found between the two media in any of the outcome parameters were in the number of cycles with failed fertilization (1/218 in 'in house' medium compared with 10/230 in commercially prepared medium; P = 0.0186), and in the rate at which embryos cleaved. Thus, while the median number of blastomeres per embryo was no different in the two groups at 46-49 h post insemination (three in embryos cultured in 'in-house' medium, compared with four in those cultured in commercially prepared medium; P > 0.1), the number of embryos per cycle that had cleaved to the 4-cell stage by 46-49 h post insemination was significantly greater in the Medi-Cult than in the EBSS medium (P < 0.001). (+info)
B-chain sequence and in situ hybridization of the rabbit placental relaxin-like gene product.
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We reported that the nucleotide sequence of a cDNA generated from rabbit placental poly(A)(+) RNA using porcine preprorelaxin primers was identical to SQ10, a product of squamous differentiated tracheal epithelial cells. However, these results did not confirm that SQ10 was the biologically active rabbit relaxin that had been isolated previously yet not sequenced. In this study, a 7-kDa protein isolated from rabbit placentas exhibited relaxin bioactivity and cross-reacted with a porcine relaxin antiserum. A partial amino acid sequence of this protein revealed a sequence identical to that of SQ10. Although the amino acid sequence of the putative relaxin receptor-binding domain found in the B chain of relaxin was modified in SQ10 from CGRDYVR to CRNDFVR, the placental protein was bioactive. These results suggest that SQ10 is the rabbit relaxin. In situ hybridization, using an SQ10 riboprobe, indicated radiolabeling in the syncytiotrophoblast cells of the rabbit placenta. The pattern of labeling corresponded with the immunohistochemical staining for relaxin observed with use of a porcine relaxin antiserum. These results indicate that the syncytiotrophoblast cells are a site of synthesis for SQ10 and that the immunostaining is not solely the result of sequestering SQ10 through receptor-mediated endocytosis. A potential role for relaxin in implantation is discussed. (+info)