Women have been offered in vitro fertilization (IVF) for quite some time now, and it's becoming more and more popular. The struggle with infertility affects approximately 10-15% of couples globally. IVF has revolutionized the realm of fertility treatments, offering hope to many families. However, the success rates of IVF have been subject to multiple factors, including age, health of the mother, whether fresh or frozen embryos are utilized, etc. There are many women who are freezing their eggs because they've reached a certain age and still haven't gotten married and had children. Their plans are to use those frozen eggs later down the line with the IVF process to produce a healthy pregnancy and baby. But the success rate isn't as high as you might think it is.
IVF Success Rate Really Isn't That High
In the realm of assisted reproductive technology, in vitro fertilization (IVF) has increasingly become a go-to choice for individuals and couples seeking to grow their families. However, many might ponder on the success rates attached to this process. Comprehending the success rates involves understanding the IVF process. It starts with hormone shots stimulating multiple egg growth over a fortnight, followed by a needle aspiration procedure to extract the mature eggs. These eggs then pair with sperm in a lab setting to enable fertilization, leading to the creation of embryos.
"At the blastocyst stage, embryos can be transferred into the body, frozen or biopsied for genetic testing," Dr. Natalie Crawford, a renowned fertility expert and co-founder of Fora Fertility in Austin, Texas, told Today.
People resort to IVF for various reasons like age-related infertility, genetic disease carriage, egg donation requirement, severe male infertility, ovulatory disorders, or fertility preservation. However, the success rates of IVF significantly correlate with the age of the egg in cycles without genetic testing for aneuploidy. Aneuploidy refers to genetic abnormalities that escalate with age, thereby increasing miscarriage risk and reducing pregnancy rates. Despite this, "with pre-implantation genetic testing of the embryos for aneuploidy, we expect success rates (live birth rate) or about 60-65% per genetically normal embryo," adds Dr. Crawford.
According to Dr. Crawford, maternal age is the chief factor influencing IVF success rates, with younger eggs boasting superior quality and higher odds of normal genetics. Ovarian reserve is another determinant; the more eggs they can extract in a single month, the higher the chances of success. Smoking habits can also reduce success rates.
Age-specific IVF success rates, according to data from the Society for Assisted Reproductive Technology, reveal that women below 35 enjoy a 51% live birth rate for a singleton birth using their eggs. The rate dwindles to 38.3% for women aged 35-37, 25.1% for those between 38-40, and 12.7% for the 41-42 age bracket. For women older than 42, the IVF success rate plummets to 4.1%.
As Dr. Crawford puts it, “Ultimately, the thing that impacts outcomes the most is maternal age, so getting started sooner is ultimately better if IVF is needed." These statistics highlight the crucial role of age in determining IVF outcomes and underscore the necessity of timely decision-making when considering this path to parenthood.
A study conducted by the Ahvaz Jundishapur University of Medical Sciences in Iran, analyzed 2,872 infertile women’s files who were candidates for IVF. Of these, 1,628 underwent fresh embryo transfer (ET), and 1,244 underwent frozen embryo transfer (FET). The study assessed and recorded various pregnancy outcomes, including clinical pregnancy, ongoing pregnancy, live births, and complications.
Results indicated that pregnancy was achieved in 19.23% of patients who underwent fresh ET, compared to a higher 28.62% in the FET group. Furthermore, the rates of clinical pregnancy, ongoing pregnancy, and live births were significantly higher in the FET group than in the fresh ET group. These findings clearly point towards greater success rates with FET. The live birth rate in the ET group was 15.65% and 38.76% in the FET group.
This Is Why So Many IVF Embryos Fail to Survive
In the pursuit of understanding fertility challenges, researchers from Columbia University Vagelos College of Physicians and Surgeons have delved into the complexities of early human embryo development. Their groundbreaking work, recently published in the journal Cell, uncovers the leading cause of embryo failure: spontaneous DNA replication errors during the initial stages of cell division. These findings not only illuminate the complexities of human reproduction, but they may also pave the way to improving in vitro fertilization (IVF) success rates.
Approximately 24 hours after fertilization, a human egg initiates cell division. This process necessitates the accurate duplication of more than 3 billion base pairs of DNA across 46 chromosomes. These duplicated chromosomes must then be accurately separated so that each new cell receives an identical set.
"However, it's a challenging task for the early embryo," explains Dieter Egli, Ph.D., the study leader. Often in IVF-created embryos, this process misfires, leading to cells within the embryo having too few or too many chromosomes.
Traditionally, the scientific community attributed these errors to the final phase of cell division, when the newly duplicated chromosomes are separated. The suspected culprit was the microtubule spindle, the mechanism responsible for dividing the chromosome sets.
Contrary to this longstanding theory, Egli’s research discovered that chromosomal abnormalities mainly arise from errors occurring much earlier in the process, when the DNA is duplicated. When DNA duplication is imprecise, it results in spindle malfunction, leading to an incorrect number of chromosomes in each daughter cell.
“The integrity of the genome, being so crucial for normal development, should not be compromised, which is why this aspect was overlooked in earlier studies,” states Egli.
These DNA copying errors appear to be initiated by obstacles within the DNA’s double helix. Although the precise causes of these obstacles remain unknown, they disrupt DNA duplication, causing it to stall or even halt. This disruption results in DNA breakage and, consequently, an abnormal number of chromosomes.
These DNA replication errors can occur as early as the first cell division cycle in human embryos and continue into subsequent cell divisions. If too many cells in the early embryo are affected by these chromosomal abnormalities, the embryo cannot progress further.
Given these findings, it's no surprise that many human embryos created for IVF cease developing mere days after fertilization. “This inefficiency of human development is an obstacle to successful fertility treatments,” says Jenna Turocy, MD, a fertility specialist and co-author of the study.
Understanding these challenges illuminates the emotional and financial burden that many women undergoing fertility treatment face, often requiring multiple IVF cycles with no guarantee of pregnancy. Unfortunately, not many women fully understand these success rates and the science behind IVF, which can lead to unexpected disappointment if they don't end up with a healthy baby. Women deserve to know what the success rates really are, especially if they are nonchalantly planning on freezing their eggs at a young age so they can do IVF later down the line.
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