Interesting article regarding IVF

BOSTON (Reuters) - What a difference two days makes -- at least for test-tube babies.

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Once a fertilized egg is implanted in the womb, the chance of delivering a child is about 48 percent higher if that egg is five days old instead of three, doctors in Brussels have discovered.

The research published in this week's New England Journal of Medicine found that 32 percent of the 175 women who received the more mature eggs ultimately delivered a baby, compared with 22 percent for the 176 who received the younger eggs.

In a journal editorial, Laura Schieve called the results "encouraging" but said the fact that the study was done in women under age 36 means the findings only apply to less than half the U.S. women receiving fertility treatments.

The new results come as fertility doctors are trying to improve the success rate for creating test-tube babies without implanting more than one embryo.

Although using multiple embryos improves the odds of success, it also increases the risk of multiple births, many of which produce children with developmental problems that can be expensive to treat.

In the United States in 2002, 35 percent of the deliveries using test-tube technology produced twins, triplets, or more. In Europe, the rate is about 25 percent because doctors are more likely to implant just one embryo at a time. The normal rate for multiple births is just 2 percent.

The Belgian study was an attempt to improve the success rate for an individual embryo by giving it two extra days to mature. The delay also allowed doctors to better gauge its quality.

Schieve, an epidemiologist at the Centers for Disease Control and Prevention in Atlanta, told Reuters that doctors have considered that implanting the embryos at a later stage might be better because, in natural conception, the embryo usually does not attach itself to the uterus until the fifth day. By the third day, the egg is usually still traveling down the Fallopian tube.

Until 1998, most centers did not have the right tools to grow embryos for more than three days.

"If you think of in-vitro fertilization in stages, from stimulating egg production, to retrieving eggs, to fertilizing them and transferring them, they're really good at stimulating and retrieving them, and fertilization rates are high. The rate-limiting step is implantation into the uterus. This is one mechanism where you might improve that," Schieve said.

Re: Interesting article regarding IVF

Thanks Ariella, can you post a link to the source?

Funny, I have a hand-out from SIRM where they talk about keeping the egg in vitro for 5 days but changing the medium to most closely resemble the fallopian tubes and uterus depending on the stage... I will try to post too...

Message edited 3/16/2006 10:48:12 AM.

Re: Interesting article regarding IVF

Here is the excerpt -- if anyone wants the whole doc. let me know...

b. EMBRYO VERSUS BLASTOCYST TRANSFER It has long been recognized that the more advanced the embryo’s state and rate of development, the more likely it is to implant successfully into the uterine lining. It is also well established that “poor quality embryos” tend to divide (cleave) and develop more slowly, and are much more likely to arrest before reaching the blastocyst stage. It is therefore not surprising that researchers would focus on trying to grow embryos to the blastocyst stage in order identify “good quality embryos” that are more likely to implant successfully, by their ability to survive to the blastocyst stage of development.

Over the past five years, researchers in Australia, Scandinavia and in the U.S a simultaneously developed a new generation of culture media that reliably support the growth of embryos to the fifth or sixth day. This development was based on the premise that the metabolic needs of the early embryo change as it moves from the fallopian tube to the endometrial cavity and the new media are designed to mimic these environmental changes. Using “sequential culture systems,” approximately 40% of ‘good quality” (7cells or more) day 3 embryos can be grown to the blastocyst stage and have made blastocyst culture feasible for many IVF programs.

The current inability to predict with certainty which embryos will successfully implant into the uterine lining still prompts many IVF practitioners, motivated with the desire to optimize IVF success rates, to transfer large numbers of embryos at a time. While such practice indeed increases IVF pregnancy rates, it unfortunately also results in an unacceptably high incidence of multiple pregnancies, with devastating consequences to the resulting, often severely premature, newborn babies.

It is important to note that in spite of the introduction of specialized culture media and new techniques for culturing blastocysts, it is still only possible to enable about 40% of “good quality” embryos to progress to blastocysts. However, since blastocysts are more likely to implant than are 3 day “good quality embryos”, it is possible through the selective transfer of fewer blastocysts to improve IVF success rates while at the same time, significantly curtail the incidence of high-order multiple pregnancies (triplets or greater).

However, few would argue that the uterus likely provides a better environment for embryos to flourish than the incubator in an IVF laboratory. The presumption has always been that it would probably be best to transfer healthy embryos to the uterus sooner rather than later. Moreover, even the best microscopic embryo grading systems are inherently flawed because they do not have a high level of negative or positive predictive value. Although an improvement of most other embryo grading systems, the Graduated Embryo Scoring (GES) system developed at SIRM is also somewhat limited in this regard.

Re: Interesting article regarding IVF

Thanks Kara and Ariella !!!

Re: Interesting article regarding IVF

I hope this works- here is the link. //www.theaustralian.news.com.au/common/story_page/0,5744,18484979%255E23109,00.html

Message edited 3/16/2006 12:54:14 PM.

Re: Interesting article regarding IVF

I have read a LOT about this and I was always interested to see how infrequently clinics actullay use a 5 day transfer unless they think the egg quality is poorer versus using it when the egg quality is good because the chance of implantation is so much higher...

Good articles...