‘By freezing their eggs, women can extend their fertility’
By Sola Ogundipe
MIRANDA, a 29-year-old mother of two has just had her eggs frozen and stored. The decision was not by chance but by choice, she told Good Health Weekly last week at her Lagos home.
Miranda is one of the fast growing group of Nigerian women who opt for egg freezing and storage for the pupose of bearing children in future. The decision to take this revolutionary step was borne out of necessity.
She was diagnosed with cervical cancer last year and hopes to continue to bear children from the frozen eggs as soon as she completes the series of radiotherapy and chemotherapy treatment.
Biologically, a woman’s fertility declines in her 30s. Thanks to egg freezing, the ticking biological clock can be quietened.
The origins of egg freezing in fertility treatment go back to the late 60s, with experiments on mice.
The first successful pregnancy from a frozen egg occurred in 1986, in Australia. But while the procedure was developed by doctors to help cancer patients and women at risk of an early menopause, however, fertility experts believe that more and more women flocking to fertility clinics in Nigeria may be doing so more for medically advised reasons than for social reasons.
Dr. Abayomi Ajayi of Nordica Fertility Clinic, Lagos, Asaba and Abuja, notes that egg freezing has become increasingly popular in women between the ages of 21 and 43. “Some women opt for this procedure because they are not ready to have a baby, while others are undergoing treatment for an illness that requires chemotherapy or therapy to a part of the body near the ovaries.”
Late last year, the American Society for Reproductive Medicine issued new guidelines declaring that egg freezing should no longer be considered experimental.
Under the new guidelines, fertility specialists and researchers are urging use of the procedure for women who have a medical condition that may destroy their reproductive organs.
Health experts hope to encourage more women to consider the option, and push insurance companies to pay for the procedure.
Nearly 97 percent of eggs studied during randomized trials were found to be functional after they were thawed. Approximately 40 percent to 60 percent of women who undergo in vitro fertilization, IVF using previously frozen eggs were all able to successfully conceive.
The guidelines recommended the use of egg freezing for women who want to preserve their fertility if they are undergoing chemotherapy or radiation; planning to have their ovaries removed because they carry a gene mutation that puts them at high risk of ovarian cancer, or are undergoing IVF with a partner and prefer not to freeze their embryos for ethical reasons such as having to determine whether to destroy leftover embryos in the future.
But there are concerns. Among this is a risk that women who delay starting a family for too long may never be able to have a baby naturally. Also, the British Fertility Society (BFS), a multi-disciplinary organisation which represents professionals working in reproductive medicine, expresses ethical concerns about egg freezing being used by women as a way to delay motherhood.
But, According to Ajayi, “There’s currently no treatment that will slow down the decline in the number of good quality eggs a woman has. The best we can do is get them out while the eggs are young and plentiful and freeze them.”
Women are born with around two million eggs. And by the age of 30, 95 per cent of women have less that 15 percent of their eggs left
The latest advance of the freezing technique called vitrification, utilises chemicals are used to dehydrate the egg before it is frozen. When thawed, 98 per cent of vitrified eggs survive.
Vitrification is a technology used to freeze human eggs and embryos so that they can be stored for later use. It is a technology that has many uses outside of embryo freezing, as it allows something with a crystalline structure to be converted into something very smooth. A classic example is the creation of glass using sand (which is crystalline) as the main ingredient. In recent times, there has been a dramatic worldwide shift to vitrification from slow freezing.
Vitrification is an ultra-rapid process at thousands of degrees per minute. A typical embryo vitrification process cools the cells in the embryo at rates close to 5,000 degrees per minute.
The process also depends on much higher concentration used for slow freezing. Typically, eggs that are vitrified are exposed to 5-10 times more cryoprotectant than slow frozen embryos. The actual concentration depends on how fast the embryo can be cooled, and the faster the rate of cooling,
Essentially, vitrification has three critical components. First, eggs or embryos are exposed to high concentrations of cryoprotectants to allow rapid dehydration of cells. Second, the eggs or embryos are loaded into tiny storage devices (usually straws) that will facilitate ultra-rapid cooling, and third, the straws containing the eggs/embryos are cooled as fast as possible, typically at thousands of degrees per minute.
For egg vitrification, the exposure to the equilibration solution is usually about 15 minutes, and it is broken up into four steps. This slow stepwise approach is designed specifically for the egg and critical to the survival of the eggs and must be followed exactly. Moving the eggs into vitrification solution, loading and cooling the straws is the same as is done for embryos.
When patients return to use their vitrified embryos or eggs, the vitrification procedure described above is reversed to allow warming back to room temperature and then 37°C, and to allow for rehydration. Since the eggs/embryos are not technically frozen (no ice was formed). The procedure “warms” the eggs/embryos in just 20 minutes and they are placed back in the incubator at 37°C in the laboratory. Embryos can be transferred back to the uterus immediately and eggs can be injected with a single sperm 3-4 hours later.
The vitrification technology is so new that statistics are not yet available. According to Ajayi, the procedure is carried out in a fertility clinic which offers counselling, information including details about cost of the treatment.
In Nigeria, currently there is no body regulating assisted reproductive technology including fertility treatments such as IVF and the storage of sperm and eggs. But the procedure is designed after what obtains in the United Kingdom, where the statutory regulatory body is the Human Fertilisation and Embryology Authority, HFEA.
In an initial consultation, an embryologist assesses the medical health, carries out a blood test to measure the woman’s level of Inhibin B – a fertility hormone produced by the ovaries. The more of it, the more eggs the woman has left.
She is given special drugs for around 10-12 days to stimulate her ovaries to “super ovulate” but is monitord closely to avoid over stimulation.
An operation – which takes around 15-20 minutes – is then performed using a sedative. The growth of the ovarian follicles are checked by an ultrasound.
A dose of hormone is given to prompt the release of eggs. The embryologist collects around 10 -12 eggs using a fine needle inserted via the vagina into the ovaries to lift out the eggs.
Now, embryologists are using a newer, more effective technique which protects the eggs using a chemical solution based on a type of alcohol. To prevent damage to the egg, the technique now removes most of the water from the eggs and protects them with a kind of ‘antifreeze’.
The eggs can be stored for up to 10 years in liquid nitrogen at minus 196 degrees centigrade.
When it is time to have a baby, the egg is thawed slowly with a carefully controlled drop in temperature before being warmed up again. After being injected with sperm, the egg is then inserted into her uterus – rather like a smear test. If the technique is successful, the patient becomes pregnant as normal.
In 2011, almost 27,000 babies were born to mothers over the age of 40 last year – a 50 per cent increase over the past decade. Experts say the figure could be well over 50,000 in 10 years’ time.