Ever wondered what the process is like to freeze your eggs or embroys? Or is there even a difference in the two? We speak with Dr Roland Chieng, Medical Director of Virtus Fertility Centre and Dr Liow Swee Lian, Scientific Director of Virtus Fertility Centre to get the lowdown.
- What is the difference between freezing eggs and freezing embryos?
An egg is a single reproductive cell, the largest single cell in the human body. Egg freezing is a way to store a woman’s unfertilised eggs in a frozen state, with a view to them being thawed at a later date and fertilised with sperm to create a pregnancy. Eggs can be stored for many years, giving a woman suffering from a medical condition the freedom to complete treatment before starting a family.
The process to freeze eggs involves: the ovaries being artificially stimulated with a course of hormone injections, encouraging the production or release of multiple eggs. These eggs are collected in a minor surgical procedure and frozen for storage.
When a woman is ready to use her frozen eggs, they are thawed and then fertilised with sperm, either from a partner or a donor. A healthy fertilised egg will develop into an embryo, which is then transferred to the woman’s uterus, with the aim of developing into a successful pregnancy.
An embryo in contrast is an egg that has been fertilised by a sperm and as it develops it is a mass of cells. Embryo freezing has been a proven technology for much longer than egg freezing. Embryos tolerate freezing considerably better than eggs as an embryo is a mass of cells and therefore more robust. So subsequent embryo survival and the chance of a pregnancy is much higher following embryo freezing. Pregnancy success rates can depend on the age of a woman’s eggs at the time of IVF treatment ie at the time of the embryo creation.Up until recently, attempting a pregnancy using frozen eggs had a much lower chance of success.
Eggs appear to be more sensitive to the freezing process and it is only within the last 5 years that the technology has improved, mostly using a newer freezing technique called vitrification, which has allowed the pregnancy rate to slowly approach the one we see with frozen embryos.
How does the “freeze-all” policy at Virtus Fertility Centre work?
Although fresh embryo transfer (ET) is the norm in most in vitro fertilization (IVF) centres, there is increasing interest in the freeze-all policy. In this strategy, the entire cohort of viable embryos is electively cryopreserved and a delayed frozen embryo transfer is performed (ie the frozen embryo is thawed and then transferred to the woman). However this can only be considered as a potential strategy if the laboratory conditions are optimal.
Today we typically allow an embryo to develop for five days in the laboratory and in fact instead of transferring fresh at day 5 the majority of our patients freeze all their embryos and wait a month until their body settles after the hormone stimulation involved in the IVF cycle and we transfer a thawed embryo the next month during a ‘natural’ cycle.The potential advantage of this strategy is that the embryo transfer is performed in a more favourable intrauterine environment for implantation, and patients are typically more emotionally stable, less anxious, which has a positive impact on a successful IVF outcome.
The ‘freeze-all’ approach to treatment is new and not common in Singapore however there is significant published literature that supports the approach which shows good pregnancy outcomes in all age groups under specific laboratory conditions.
What is an ideal age for ladies to freeze their embryos and is there any side-effect in doing so?
Generally, the success rate of the IVF procedure is higher with embryos that have been created from younger eggs. It is therefore very reasonable for women in their late 20’s to late 30’s to consider having this procedure as women in this age group show a pregnancy rate of up to 40 per cent. The pregnancy rate however falls to 15 per cent once the woman reaches 40 years and in Singapore, the IVF age limit is 45 years.
What are some common fertility issues faced by Singaporean couples and how does this policy help them?
Up to 1 in 6 Singaporean couples can experience difficulties when trying for a baby and up to a third of couples will have difficulties due to a combination of male and female factors. After a woman’s age, male infertility is the single biggest reason a couple may have trouble conceiving.
Infertility in women can be caused by an ovulation disorder, blockages in the fallopian tubes or other complications in the uterine environment. Some of the most common conditions that can affect a woman’s fertility include: Polycystic Ovarian Syndrome (PCOS), endometriosis and fibroids. Infertility in men is most commonly due to no or very few sperm produced and/or found in the ejaculate. Sometimes sperm are malformed, and in rare cases genetic diseases may be at fault. Other complications can include immunological infertility, retrograde ejaculation, blockages in the vas deferens or subnormal quality of sperm.
Fertility in both the woman and the man can also be affected by lifestyle choices such as smoking, excessive drinking or being severely under or overweight.
Share with us three advice you would give to couples who are trying to have a baby.
Lifestyle changes – both partners should avoid alcohol (binge drinking in particular), stop smoking, achieve a healthy Body Mass Index and keep an active lifestyle. Seek help early – for women who are above 35 years old, seek help early if you have been trying for a child for 6 months with no success naturally. For women who are under 35 years of age and have been trying for 12 months unsuccessfully naturally seek help. Have a fertility assessment together – infertility issues affect both men and women. We encourage men and women to go for fertility assessment together for accurate assessment, diagnosis and personalised treatment recommendation.