Freezing embryos
IVF techniques have improved by leaps and bounds.
IN 2003, a woman named Li in northwest China’s Shaanxi province was diagnosed with polycystic ovarian syndrome. She also had blocked fallopian tubes.
Realising that her condition could affect her fertility and chances of pregnancy, she opted to try her luck using in vitro fertilisation ( IVF).
During her IVF cycle in 2003, doctors harvested 12 eggs from her ovaries and created 12 embryos with her husband’s sperm. She had two fresh embryos transferred into her womb, and froze the rest.
Li gave birth to a healthy boy in 2004.
When China dropped its onechild policy last year, the couple decided to have a second child. So they went back to the hospital to see if they could get pregnant again using the frozen embryos they stored 12 years ago.
Li underwent a frozen embryo transfer ( FET) cycle, and gave birth to a healthy baby boy on February 24, 2016.
Consultant gynaecologist and fertility specialist Dr Leong Wai Yew explains that the success of the cryopreservation technique can be attributed to the use of ultrarapid freezing process ( vitrification) prior to cryopreservation, which prevents the formation of intracellular ice crystals and significantly increases embryo survival, implan- tation and pregnancy rates.
There are a few vitrification methods available today which have varying degrees of post- thaw survival rates. Some are able to consistently provide a 100% postthaw survival rate for embryos/ blastocysts, making it possible to achieve significantly higher clinical pregnancy rates than fresh IVF cycles.
Furthermore, the introduction of preimplantation genetic screening ( PGS) and preimplantation genetic diagnosis ( PGD) using methods such as micro- array comparative genomic hybridisation ( MaCGH) and gene sequencing ( NGS) allow embryos to be “screened” first to make sure it has all 46 chromosomes ( i. e. euploid) and carries no genetic abnormalities.
The advantage of combining PGS/ PGD with embryo freezing allows for the cryo- storage of embryos over several cycles before performing blastocyst transfers.
This combination vastly improves the efficiency of embryo transfer, while at the same time reduces the risk of miscarriage and chromosomal birth and single- gene defects.
“The shift towards embryo freezing is not surprising since it has many advantages,” comments consultant gynaecologist and fertility specialist Dr Haris Hamzah.
“Since FET is done at least one to two months after a woman’s ovaries have been stimulated with stimulation drugs, it allows sufficient time for the woman’s hormone levels to return to normal, which mimics a more natural conception process,” adds Dr Leong.
Frozen embryo transfer has enabled many couples to have children and enjoy the journey of parenthood. So, make sure you do your homework and consult a fertility expert to find out more, as well as to discuss your options.