> The use of oocytes frozen influence results, obstetric or perinatal?

  • Introduction
  • The study
  • Use of cryopreservation
  • Conclusion

Introduction

The technology of assisted reproduction (ART, ART in Italy) has had amazing improvements since the announcement of the first birth following the use of the in vitro fertilization (IVF) in 1978. The cryopreservation of the embryo, the use of gametes from donors, surrogacy, screening of the embryo for genetic problems, and, more recently, the cryopreservation of oocyte, and ovarian tissue are procedures available through ART.

The first pregnancy with success following cryopreservation of the oocyte has been recorded in 1986. The più wide availability; the freezing of oocytes, however, not è been a reality until very più later, because of technical problems related to the procedure.

The mature oocytes are sensitive to freezing, and the percentages of survival and subsequent fertilization and embryo development were not acceptable. Technological improvements and the introduction of vitrification, however, were associated with significant improvements in the cryopreservation of the oocyte. With current technology, approximately 90% of the oocytes survive the freezing-thawing process. On the basis of recent results, in 2013, the companyà of the fertilityà have reclassified the cryopreservation of oocytes as non più experimental.

Who are the patients that can benefit from this technology?

cryopreservation of the oocyte is recommended in the first place to the patients who have a diagnosis of cancer and wish to preserve their fertilityà before starting the therapy. Patients with medical conditions (chronic diseases of autoimmune, severe endometriosis) that can expect to be subjected to surgical procedures or doctors that can impair ovarian function.

The eggs can be frozen and also during standard treatments IVF così as when the partner is not able to provide sperm on the day of the retrieval of the egg, or when, for ethical reasons, the couple wants to limit the number of ovules fertilized.

The freezing of the ovum makes it possible to organize banks donor of the oocytes donated, where the rules require anonymous donation. Finally, the donation of the egg può be considered for later personal use when a woman, for various reasons, decides to post-place the right children.

As with any new technology, its safety must be established. This article is about of results obstetric and perinatal with the use of oocytes vitrificati.

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Lo studio

The report is a retrospective analysis based on treatments involving fresh and frozen oocytes from a single center of fertilityà. The available data were based on reports from about 80% of the women undergoing treatment. The lack of complete response rates than those treated has limited the sample size 1224 children born following the use of oocytes with fresh and 1027 children born according to the use of oocytes vitrificati.

The use of own oocytes or donated has been analyzed together and also separately. The data were collected for patient characteristics and treatment, and confounding variables were controlled during the analysis.

The women who used egg vitrificati were slightly più old, had più probability; have had previous miscarriages and had less parts pre-term. They also had più probability; to be bad respondents, thereforeò, the use of donor eggs donor was più frequently among them. The number of mature oocytes was più high in the group of oocytes fresh.

Of the pregnancies with the use of oocytes with fresh, 77,1% were single, while the corresponding figure was 72,6% in the group with oocyte vitrificati. The percentage of pregnancies anembrioniche was comparable. No data have been provided on the losses in the first quarter or early in the second. Età gestation at the time of birth, birth weight and risk of low birth weight and small for the età of gestation were comparable. The incidence of minor and major birth defects did not differ between the groups, and the needà of hospitalization in the icu was also similar. The risk for medical problems during pregnancy was comparable between the groups.

When the analysis was limited to the use of their oocytes, yet there was no difference in the results obstetric and perinatal among the groups of oocytes with fresh and vitrified. The only difference was a percentage slightly higher level of abnormalities, but this observation was based on a total of only five cases: When the comparisons were made for multiple pregnancies using own oocytes or single or multiple pregnancies using oocytes donated, there were no differences in the results obstetric and perinatal with eggs fresh against vitrificati.

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The authors concluded that, on the basis of their experience, the use of oocytes vitrificati was not associated with più high-risk obstetrical or perinatal.

The use of cryopreservation

Currently, the indication of the più widely accepted for the cryopreservation of the oocyte is for the preservation of the fertilityà before a cancer therapy. The vitrification of the oocyte is associated with more than 90% of survival rate and percentage of pregnancy are steadily improving. A meta-analysis of 2011 has compared the results of treatment with the oocytes from fresh, vitrified, and slow-freezing, based on the results of five studies.

the Fertilization and percentage of division, availabilityà of embryos of high qualityà and rates of clinical pregnancy were comparable between oocytes from fresh and vitrified. The vitrification was superior to all of these parameters compared to slow freezing. Goldman and colleagues have found differences in the percentages of births when they analyzed the results of treatment with oocytes and fresh or frozen.

Furthermore, Peter and colleagues have found no adverse effects on the qualityà biomolecular oocytes vitrified: Noyes and colleagues have reported that a proportion of congenital anomaly of 1.3% with the use of oocytes frozen-thawed, which was not different from the percentage observed in the conceptions of nature.

Levi Setti and colleagues have reported a similar percentage of fetal anomalies with oocytes frozen against fresh, but a più high percentage of spontaneous miscarriages, with oocytes frozen (26,9% against 17,6%). Have not observed difference in età mean gestation at delivery, but the mean birth weight was più the bottom is in single pregnancies that is twins in the group in which they used the eggs fresh.

The vitrification of the ovum is often used by the programs of the donation of egg. The availabilityà of the oocyte donor frozen-thawed makes it possible to ensure the anonymous donation and continuous support without the needà to synchronize the donor and the recipient.

another indication is always più used for cryopreservation of the oocyte is the freezing of the social of the oocyte. Women who wish to postpone reproduction for reasons of work or educational or finché non are the right partner can choose to cryopreservation of oocytes for later use. In this way, they can use ova più young and fresh even when they are in the forties.

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it Should be emphasized, however, that the result of the pregnancy può be not the same, due to uterine problems or doctors who is more likely to occur in an età più advanced. The results of this study about the obstetrical complications and perinatal cannot be applied to these cases becauseé there would be no need to compare them with women who conceive spontaneously in the twenty or early thirty.

Conclusioni

The findings of this study are very reassuring for. The authors used a large sample from a single institution and this is definitely a strength of this study. A weakness, however, is that they have not had information on all patients, and this può to have negatively affected their results, especially about those parameters that were reported in small numbers, such as congenital anomalies. In addition, they have collected data on the outcome of pregnancy before 24 weeks.

più high percentage of miscarriage and termination of pregnancy due to abnormal screening results può also affect some of the parameters shown. It must also be emphasized that in almost three-quarters of the cycles used donor eggs.

Since the donor of the ovum must be a young woman, fertile and in good health, it is expected that her eggs are of high qualityà. The results obtained with these ovules may not necessarily be applied to the population, infertile or with cancer patients. A sub-analysis of the data about the ova own è been made, but in this case, the number of cases and controls was obviously very più below.

C’è need to put together more data on the outcomes obstetric and perinatal così as the development in the first and second child as a result of the use of oocytes vitrificati. It is, however, reassuring in this phase, based on the information available, have not found adverse effects with this technology.

Source: PubMed

November 17, 2014