Tag Archives: Viable Embryos

Diabetes and male infertility

Researchers have found that diabetes may affect sperm quality, after a study comparing the DNA in sperm from diabetic and non-diabetic men found more DNA damage in the sperm cells of the diabetic men.

 

The study, conducted by the research group at Queen’s University Belfast, with findings published in the journal Human Reproduction, found that around 52 per cent of the DNA in the sperm cells of diabetic men was fragmented, compared with only 32 per cent for the non-diabetic men. Fragmentation of the DNA in sperm is one of the main causes of male infertility, because it prevents the sperm from delivering intact genetic information to the egg, which is required for the creation of a viable embryo.

 

The study compared the sperm from 27 diabetic men with that from 29 non-diabetic men in their early 30s. Dr Ishola Agbaje, who lead the research project, said, ‘Our study identifies important evidence of increased DNA fragmentation of nuclear DNA and mitochondrial DNA deletions in sperm from diabetic men’. He stated that these findings would have implications for male fertility, which has already been decreasing over the last 50 years. The increasing global incidence of diabetes could further propel the decline in male fertility.

 

Professor Sheena Lewis, director of the Reproductive Medicine Research Group, and co-author of the paper, said that the study was very small, and so served to highlight a possible concern. She stated that ‘our study shows increased levels of sperm DNA damage in diabetic men. From a clinical perspective this is important, particularly given the overwhelming evidence that sperm DNA damage impairs male fertility and reproductive health’.

 

Transcription is the synthesis of RNA under the direction of DNA, and is the first step towards gene expression, where the information from the gene becomes a product such as a protein translating the genetic information into a cellular function. If there are errors in transcription, there will also be errors in the function of the gene.

 Sperm DNA quality is known to be associated with decreased embryo quality, low embryo implantation rates, higher miscarriage rates, and some serious childhood diseases, in particular some childhood cancers. Over the years possible causes for sperm DNA fragmentation have been suggested but to date the exact mechanism for the damage remains unknown, say the scientists.

 Professor Lewis said that further research would be needed to quantify the exact nature of the DNA damage caused by diabetes, and whether there were additional health effects for the children of diabetic fathers. Dr Allan Pacey, senior lecturer in andrology at the University of Sheffield, stressed the importance of the quality of sperm DNA, and further said that ‘it would be important to understand the mechanism by which this damage occurs so that if it can be avoided we can work out how to do this’.

 

Matt Hunt, science information office at Diabetes UK, called for further research, after labelling the findings alarming. He said ‘this is the first research to suggest DNA damage may be occurring at a cellular level and that it is a cause for great concern’.

 

 

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The Frozen Embryo Transfer

Frozen Embryo Transfer (FET)

If you have recently gone through infertility treatments or if you are considering undertaking IVF, you may be wondering what will happen to any extra embryos that are created during the procedure. If you and your partner have extra embryos that are not used during initial IVF procedures, these embryos can be frozen and then transferred to your uterus at a later date. Known as frozen embryo transfer (FET), this procedure has helped many couples facing infertility achieve pregnancy.

What is Frozen Embryo Transfer?
This procedure takes embryos that have been frozen for a period of time and replaces them into your uterus after they have been thawed. FET is a relatively non-invasive procedure, which is why many couples choose to have it performed. It can be successfully performed on women who are experiencing either natural or controlled menstrual cycles.Why Choose Frozen Embryo Transfer?
Many couples choose to have FET performed if they have had extra embryos remaining from an initial IVF cycle. Some couples do not like the idea of destroying embryos simply because they are “left over” from an IVF cycle. Other couples know or suspect that they will need to do IVF again in the future and prefer to freeze their embryos in order to make future IVF cycles less stressful physically for the female. 

In order to perform IVF, numerous embryos are created in order to ensure that healthy and viable embryos are available for transfer. Many couples decide to freeze some of these embryos in order to allow them the opportunity to get pregnant again in the future or for use in a later IVF cycle. 

Embryo Freezing
The FET procedure involves having your embryos frozen, or cryopreserved. The freezing procedure is as follows:

 

  • Your embryos are placed inside of special glass vials, that look much like straws.
  • These embryos are then mixed with a special solution, called cryoprotectant. This cryoprotectant prevents ice from forming in between the cells of your embryo.
  • The glass vials containing the embryos are then inserted into a controlled freezer filled with liquid nitrogen.
  •  They are cooled slowly until they reach a final temperature of -196° C.

 

Embryo Thawing
Before FET can take place, your embryos must be thawed after the freezing process. When your reproductive endocrinologist decides it is time to begin the FET procedure, your embryos will be removed from the freezer and thawed.

 

  • The embryos are allowed to thaw naturally, until they come to room temperature.
  • The embryos are then steeped in four separate solutions to help remove any cryoprotectant used during the freezing process.
  •  Your embryos are then warmed to body temperature (37°C) and mixed with a small amount of culture medium.

The Frozen Embryo Transfer Procedure

The FET procedure is actually fairly straightforward. 

Before Embryo Transfer
Before your embryos can be thawed and transferred, you and your reproductive endocrinologist need to decide how many embryos to transfer into your uterus. The number of embryos transferred will directly impact the success rate of the FET procedure. Typically, between three and four embryos are transferred during each FET procedure.

Your health care provider will then monitor your body in order to determine the best time for the embryo transfer. We usually give oral estradiol tablets to prepare the uterine lining. The thickness is measured on ultrasound scan. Your embryos will be thawed the day before your FET procedure.

The Transfer
The actual transfer of the frozen embryos is painless and straightforward, and only takes about 15 minutes.

 

  • A catheter is inserted through your cervix and into your uterus.
  • The embryos are injected into the catheter and deposited in your uterus.

 

After the Transfer
After the transfer your reproductive endocrinologist will likely have you continue any fertility medications that you may be using. Twelve days after the FET procedure, you will return to your clinic for a pregnancy test. 

Success Rates of Frozen Embryo Transfer

The success rates of FET really depends upon a variety of factors, particularly maternal age and the number of embryos transferred. Typical success rates are around 20% per cycle. It is important to know that not all embryos will survive the freezing and thawing process though. About 70% of embryos survive cryopreservation, and this can sometimes impact the success rates of FET. This makes it important to freeze and thaw a number of embryos when performing the FET procedure.

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Ovarian stimulation before IVF ‘does not influence birthweight’

German investigators claim they have produced “robust” evidence that ovarian stimulation for IVF does not influence the birthweight of resulting babies.

Singleton children conceived through IVF have lower birthweights, on average, than their naturally conceived counterparts, and it has been hypothesized that ovarian stimulation could be a cause.

To find out, Georg Griesinger (University Clinic of Schleswig-Holstein) and colleagues analyzed data from a national IVF registry with 65-70 percent coverage. They retrieved information for all IVF cycles in women aged 25-35 years who underwent ovarian stimulation and had a live, singleton birth (n = 32,416).

On multivariate regression, the baby’s birthweight was significantly and independently predicted by each of maternal height, maternal weight, duration of infertility, and the number of embryos transferred.

However, none of the parameters of ovarian stimulation studied-including duration of stimulation, use of gonadotrophins, and the number of oocytes retrieved-significantly predicted birthweight.

“The present study provides robust evidence from a large sample of IVF singletons that ovarian stimulation and birthweight have no apparent quantitative (eg, dose-response) association,” say the researchers.

However, they caution: “Although this is reassuring to the clinician, it does not invalidate the need for studying the effect of ovarian stimulation on outcomes other than birthweight, such as epigenetic alterations, and associated health disorders.”

Source: Human Reproduction 2008; Advance online publication

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Identification of Viable Embryos in IVF

A group of Australian scientists has used a new genetic analysis technique to assess IVF embryos, to identify those most likely to develop in the womb. The findings were published in the journal Human Reproduction in May 2008.

 Around one per cent of all births in the UK are from IVF treatment and the latest figures show that of 32,600 women who underwent treatment, only 11,000 resulted in births. One in four IVF pregnancies is multiple, compared with one in 80 for a natural conception.

The process of IVF involves extracting many eggs for fertilisation before choosing one, two or sometimes even three embryos for transfer into the uterus. This can lead to multiple pregnancies, which carry extra health risks for mothers and babies. Embryo selection is currently based on observations of morphology (shape and appearance) to predict their potential viability. The problem could be overcome by finding an objective, measurable means of testing embryo viability, rather than a subjective one such as morphology, to definitively pick a single, viable embryo.

 The study, carried out by scientists at the Monash Immunology and Stem Cell Laboratories, Monash University, Australia, and the Centre for Human Reproduction, Genesis Athens Hospital, Athens, Greece, recruited 48 women undergoing IVF treatment. Once their fertilised eggs reached the ‘blastocyst’ stage, an early stage of development around day five, between eight and 20 cells from the surface layer were removed. These samples were then genetically analysed using microarray techniques, which measures gene activity in the cells.

 Of the embryos selected as being viable, one or more were transferred into the 48 women, 25 of whom became pregnant, with 37 babies being born. The scientists took DNA samples from the babies, and used DNA fingerprinting to match which blastocyst grew into which baby. This enabled them to compare the activity levels of key genes, to identify which had been active in the viable, compared to the non-viable early embryos. These genes identified were involved in key processes such as cell adhesion, cell communication, cellular metabolic processes and response to stimuli.

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EMBRYO TEST BOOSTS IVF PREGNANCY RATES

A new test which helps IVF doctors pick the healthiest embryos for transfer may boost pregnancy rates by up to 15 per cent, was unveiled at a European fertility conference last week. The test, which takes just one minute to carry out and will be used alongside standard IVF methods for embryo selection, is due to start trials later this year and may be available in clinics early next year.
‘We fail to get patients pregnant about two-thirds of the time we transfer an embryo, and one of the reasons is we are not very good at picking the best ones from those available,’ lead researcher Denny Sakkas, professor at Yale University school of medicine, told delegates at the European Society for Human Reproduction and Embryology annual meeting.
Conventional IVF relies on choosing embryos for transfer by examining their size and shape under a microscope. But the researchers found that this method was only accurate at identifying viable embryos – those which would result in a pregnancy – 40 per cent of the time. Their technique – known as ‘ViaTest-E ‘ – involves shining a light through the fluid surrounding the embryo in order to measure it’s metabolic activity – rather like the technique used to tell whether milk is full or half-fat.
Testing the ViaTest-E device on 500 embryos showed accuracy rates of 60-70 per cent, potentially boosting the chance of pregnancy for women under 35 in the UK from 30 percent to 45 per cent. It is anticipated that tests which help doctors select the most viable embryos will be vital in order to support the move towards single embryo transfer, a measure being implemented across Europe and the rest of the world to try and limit multiple births.
Dr Daniel Brison, co-director of the North West Embryonic Stem Cell Centre in Manchester, told the BBC that improvements to IVF success rates were urgently needed. ‘If we can get better at choosing the best embryo to implant then we can increase the efficiency of IVF, move towards single embryo transfers and thus reduce the risk to mothers and babies,’ he said.

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