UNDERSTANDING INFERTILITY
their chromosomes aligned by a spindle
apparatus along the equatorial plate. During
traditional (“slow freeze”) cryopreservation
techniques, intracellular ice crystals form
that may damage the meiotic spindle and
compromise the viability of the oocyte. More
recently, an alternative cryopreservation
technique called vitrification has allowed
us to freeze and thaw oocytes with much
greater reliability. Vitrification is performed
with high concentrations of cryoprotectants
that dehydrate the oocytes, followed by rapid
cooling in liquid nitrogen that allows the cells
to be solidified into a glass-like state without
the formation of ice crystals. Oocyte survival
rates with vitrification vary by female age
but are typically reported around 70-80%.
As embryology laboratories gained comfort
with vitrification and increasing experience
with oncofertility patients, the American Society for Reproductive
Medicine elected to remove the experimental label from OC in
2012, and according to the CDC, over 98% of fertility practices in
the United States now offer this service to their patients.
In 2017, there were nearly 11,000 OC cycles performed across
the country. At Kentucky Fertility Institute, we usually see several
consultations per week for patients interested in these services,
roughly evenly split between those referred for oncofertility and
those desiring planned OC. As these technologies are still relatively
new, the process of informed consent is especially important,
which must include the disclosure that long term outcome data
for children born from cryopreserved oocytes is not yet available.
However, short term outcomes relating to pregnancy rates and
subsequent neonatal outcomes have been reassuring and appear
comparable to those for patients using fresh oocytes in traditional
IVF treatment. Current prediction models suggest that for at least
a 75% probability of future live birth, women up to age 36 should
consider cryopreserving at least 15 to 20 mature oocytes. Due to
the higher incidence of oocyte aneuploidy in women in their late
30s, women ages 37 to 39 are typically advised to cryopreserve at
least 20-30 to achieve similar outcomes. Depending on individual
variables and preferences, some patients may require more than
one OC cycle to achieve these clinical targets.
Interestingly, the cultural reception of planned OC has been
mixed. It has been applauded for enhancing women’s reproductive
autonomy and providing an option for the dissociation of fertility
from conflicting priorities relating to education, professional
commitments or other social circumstances. Several high-profile
An unfertilized oocyte (photo courtesy Dr. Greg Christensen, PhD, HCLD)
tech companies (including Apple and Facebook) quickly added it
to their list of employee health benefits as an incentive for attracting
and retaining more competitive female employees. However, over
the past few years, a number of startup companies have launched
with the goal of marketing OC to millennials in their 20s, which
has understandably generated a fair amount of criticism. Most
women in this younger age group are unlikely to benefit from
OC, and surveys have shown a high incidence of regret in young
women who pursue it. At Kentucky Fertility Institute, we generally
advise that otherwise healthy women in their 20s be managed with
education, counseling and serial assessments of ovarian reserve
metrics. To optimize the value of OC, careful patient selection
and counseling are key. Our typical patients pursuing planned OC
are in their mid-30s, and we have observed that most either have
highly-demanding jobs (e.g. physicians and executives), or are
newly single after ending a long-term relationship.
Female aging remains one of the most difficult barriers to
fertility for us to overcome in a clinical setting, and despite its
limitations, planned OC is among the most effective preventive
interventions we have available at the current time, particularly
for women who prioritize the use of autologous oocytes in their
family-building goals. From its origins in oncofertility to its
rapidly-expanding contemporary applications in family planning,
OC will undoubtedly have a valuable role in modern reproductive
care for the foreseeable future.
Dr. Hunter is the Practice Director of the Kentucky Fertility Institute.
SEPTEMBER 2019
27