Advances in reproductive medicine mean that women now have several options when considering fertility preservation.
Women consider fertility preservation for a number of medical and personal reasons, according to the National Institutes of Health (NIH) Eunice Kennedy Shriver National Institute of Child Health and Human Development.
If you are affected by cancer, the treatment you undergo may damage your ovaries, leaving you unable to have babies in the future. The same might hold true if you have been exposed to toxic chemicals in your workplace or during military service.
Preserving your reproductive tissues can allow you to delay childbearing in these instances.
But benign conditions can also affect your fertility. Non-cancerous tumors, endometriosis, or uterine fibroids can put you at risk of premature ovarian insufficiency, which means that your ovaries stop producing eggs, or oocytes, at an earlier age than they normally would.
This can also happen even if there is no clear link to such benign conditions. Your menopause may then start before you reach the age of 40, and genetic reasons are thought to be the root cause.
But the risk of infertility or premature ovarian insufficiency are not the only reasons why women consider fertility preservation.
"The largest group of women seeking fertility preservation," explains Dr. Jacques Donnez — a professor at the Société de Recherche pour l'Infertilité and Université Catholique de Louvain in Brussels, Belgium — "consists of those who wish to postpone childbearing for various personal reasons, the biggest threat to their fertility is age."
In an article published this week in The New England Journal of Medicine, Prof. Donnez explains the latest advances in the field and outlines which options are available for women to preserve their fertility.
How to preserve fertility
There are several different ways to preserve fertility: frozen embryos, frozen eggs, and frozen ovarian tissue.
The earliest method of fertility preservation made use of previously frozen embryos, which are implanted at a later date in a similar way to in vitro fertilization (IVF).
But one drawback of this technique is that a male partner or sperm donor is required to fertilize the woman's eggs to produce the embryos before they are frozen. In some cases, especially in young women and girls, this is not an option.
Next came the freezing of oocytes. Here, the eggs are frozen and then thawed at a later date. Once they are fertilized, the embryo can be implanted.
The first baby conceived using this method was born in 1986. However, the devil is in the detail; cells generally do not like to be frozen and are very susceptible to damage from ice crystals formed as a result of the freezing method.
A newer method of preserving oocytes is vitrification, which is very rapid freezing "in the absence of ice."
Speaking to Medical News Today, Prof. Donnez explained that the field has come a long way since the first IVF babies were born more than 40 years ago. These days, it is possible to obtain good-quality oocytes and preserve these through vitrification.
The key to success lies in the age of the woman undergoing the treatment, he explained.
"You see that there is a huge difference between the success rate of oocyte vitrification depending on the women's age. Ideally, women have to vitrify their oocytes under the age of 30, when the quality of the oocyte is perfect."
Prof. Jacques Donnez
"If a women comes to vitrify her eggs at, say, the age of 38, the chances of success are much lower," he added.
Freezing ovarian tissue
Freezing tissue from the ovaries, rather than the eggs themselves, is another way of preserving fertility. This is really the only option for girls who have not reached puberty yet, or women who cannot delay cancer treatment, because oocytes cannot be collected in these cases.
"When we started work on this in the early 2000s, we had mostly women with cancer in mind. But then we started to apply it in cases of benign disease, like endometriosis," Prof. Donnez told MNT.
During ovarian tissue cryopreservation, small pieces of ovarian tissue — or, in some cases, the entire ovary — are frozen and then re-implanted. In 95 percent of cases, the ovaries are functional for 4–5 years, although in some cases, this can be 7 years or more. The first pregnancy using this technique was in 2004, and since then, more than 130 babies have been born using this method.
"Transplanted ovarian tissue can be active for more than 7 years. This gives [a much bigger] advantage to restore fertility and the natural span of fertility," Prof. Donnez explained.
As with oocyte vitrification, age is once again a deciding factor in the success of this technique. As Prof. Donnez puts it, "[T]he same applies for cryopreservation of ovarian tissue, before the age of 25 ideally, because we know that the number of follicles and number of eggs is highest in really young women."
At this moment in time, the American Society for Reproductive Medicine considers this technique as "experimental". However, Prof. Donnez would like to see this become a routine way to preserve fertility.
"If you look at the figures, there are now more than 130 live births and the technique is now widely accepted. With the good results that we have and in the absence of side effects, it's time to consider this technique as a clinical application," he explained.
Advances in fertility preservation techniques mean that women and their healthcare professionals have a wider range of choices to address their specific needs. "That's a perfect equation for women who have chosen to have children later in life," Prof. Donnez told MNT.
"Women have their first baby later and later. Some of them have a baby after 35, when we know that their natural fertility is already decreased. The options for fertility preservation are adequate for women, who make such a choice."
Prof. Jacques Donnez
Yet for some women, using their own eggs or ovarian tissue carries an inherent risk.
Avoiding cancer in the future
Dr. Marie-Madeleine Dolmans — who is a professor at Pôle de Gynécologie, Institut de Recherche Expérimental et Clinique, Université Catholique de Louvain, and the Department of Gynecology at Cliniques Universitaires Saint-Luc, also in Brussels — is co-author of the article in The New England Journal of Medicine and has developed an artificial ovary system specifically for these women.
"They are at risk of transplanting back tissue that could turn cancerous" if treated with their own ovarian tissue, Prof. Dolmans explained to MNT.
Instead, Prof. Dolmans and her team isolate ovarian follicles and combine them with a biomaterial called fibrin to create an artificial ovary. By using individual follicles rather than ovarian tissue, the risk of reintroducing cancerous cells is eliminated.
When the artificial ovary is transplanted, the body breaks down the fibrin and creates new ovarian tissue.
"With my team," Prof. Dolmans said, "we've worked for more than 10 years on this topic. We are able to isolate these follicles and put them in the matrix to transplant. Now we have found a good matrix in fibrin, which is a completely natural component, and will be easily approved by health authorities."
She hopes that this technology will be available to patients some time in the next 5–10 years.
"The patients who had their tissue frozen and were cured from leukemia are often very young. So by the time they become adults, we hope to have this option open to them."
As Prof. Donnez pointed out, medical innovation in fertility preservation has come a long way. The American Society for Reproductive Medicine recommend that you "[...] speak to your healthcare provider early in order to plan for your future reproductive health."
If you are considering delaying childbearing, regardless of what your personal reasons are, remember that there are options and that you should start by talking to your healthcare professional.