PRE­SERVE your FER­TIL­ITY

IVF India - - Health -

Fer­til­ity Preser­va­tion is a new way of em­pow­er­ing re­pro­duc­tive choice. Re­pro­duc­tive choice means hav­ing chil­dren when you pre­fer, rather than when you must. The fer­til­ity of youth is no longer a limited re­source, con­strained by age. Women can po­ten­tially pur­sue their re­pro­duc­tive lives at their own pace, rather than ac­cord­ing to the obli­ga­tions of bi­ol­ogy.

DID WE KNOW?

• As a lady ages, her fer­til­ity de­clines

• We, women are born with 1- 2 mil­lion eggs

• Th­ese eggs are grad­u­ally lost as you age (at a rate of about 1,000 per month) and are never re­plen­ished

• The vi­tal­ity of the eggs that re­main is re­lated to our age

• Be­yond age 30, fer­til­ity be­gins to de­cline

• Fer­til­ity de­clines rapidly af­ter age 35

• Af­ter age 40 a woman has < 5 % chance each month of con­ceiv­ing nat­u­rally

• Mis­car­riages and chro­mo­some de­fects be­come more com­mon as you age

• A woman’s fer­til­ity po­ten­tial can be de­ter­mined in part by a blood test

• Egg freez­ing po­ten­tially em­pow­ers re­pro­duc­tive choice

The tech­niques of vit­ri­fi­ca­tion of oocytes and the sub­se­quent warm­ing process be­ing used to­day are now pro­duc­ing re­sults far su­pe­rior to the re­sults that are ob­tained with slow-freez­ing tech­niques, and it would seem that this is the method of fe­male fer­til­ity preser­va­tion that will be widely used in the near fu­ture. While men are ca­pa­ble of man­u­fac­tur­ing 1000 sperm in the space of one heart­beat up to a ripe old age, the fe­male of the species steadily but surely loses her eggs from birth to menopause, with an ac­cel­er­ated loss from the midthir­ties on­ward. Ac­com­pa­ny­ing this loss of eggs is an equally se­vere de­cline in egg qual­ity with age. Con­se­quently, fe­male fer­til­ity po­ten­tial rapidly dwin­dles from the age of 37 on.

Sperm cry­op­reser­va­tion was first suc­cess­fully per­formed (in snow!) more than 200 years ago. The cry­op­reser­va­tion of oocytes for fer­til­ity preser­va­tion has been at­tempted much more re­cently but has un­der­gone a com­plex his­tory, which has been largely un­suc­cess­ful. The slow-rate freez­ing of oocytes re­sults in ex­tra­cel­lu­lar and in­tra­cel­lu­lar crys­tal­liza­tion of ice, which can cause ir­repara­ble dam­age to the spin­dle. In ad­di­tion, the egg is par­tic­u­larly sen­si­tive to chill­ing in­jury, which as­suredly can oc­cur with most slow-freez­ing pro­to­cols.

It now seems that the rapid-freez­ing method to in­duce vit­ri­fi­ca­tion of oocytes has bro­ken the ice. The first at­tempts of vit­ri­fi­ca­tion of sperm were started about 70 years ago. The tech­niques of vit­ri­fi­ca­tion of oocytes and the sub­se­quent warm­ing process be­ing used to­day are pro­duc­ing re­sults equal to those us­ing fresh oocytes and are, cer­tainly, far su­pe­rior to those us­ing slowfreez­ing tech­niques. In the last 2 years, highly suc­cess­ful sur­vival rates of oocytes of over 90% af­ter vit­ri­fi­ca­tion and warm­ing, fer­til­iza­tion rates of 75%–90%, preg­nancy rates of 32%–65% per ET, and live-birth rates of over 50% have been re­ported. Suc­cess­ful de­liv­er­ies af­ter oocyte vit­ri­fi­ca­tion have been re­ported from coun­tries as far flung as Ja­pan, the United States, Colom­bia, and Italy and Ger­many in Europe. In ad­di­tion, the vit­ri­fi­ca­tion process is con­sid­er­ably less com­pli­cated than slow freez­ing, avoids the com­pli­ca­tion of in­tra­cel­lu­lar ice crys­tal­liza­tion, and is less ex­pen­sive and time-con­sum­ing.

The ini­tial worry that the use of the high con­cen­tra­tions of cry­opro­tec­tants needed would cause toxic and os­motic ef­fects have so far proved un­founded as long as the eggs are only left in the high­est con­cen­tra­tion of cry­opro­tec­tant for less than 60 sec­onds. As­sum­ing that the safety of the vit­ri­fi­ca­tion of oocytes will con­tinue to be ver­i­fied, it would seem that this is the method of fe­male fer­til­ity preser­va­tion that will be widely used in the near fu­ture. The re­ported suc­cess of the use of this method should stim­u­late a re­newed de­bate on oocyte stor­age for fer­til­ity preser­va­tion with­out a med­i­cal in­di­ca­tion (as­sum­ing that im­pend­ing ovar­ian fail­ure is not a med­i­cal in­di­ca­tion). We be­lieve that the time has come to con­sider re­dress­ing the bal­ance be­tween the male and fe­male fer­til­ity po­ten­tial now that we ap­par­ently have the tech­nol­ogy to do so. While sperm may be nat­u­rally ca­pa­ble of in­duc­ing a preg­nancy even up to the age of 80, the limited re­pro­duc­tive life span of oocytes has re­stricted women to con­ceiv­ing and de­liv­er­ing a baby up to the age of 45 at best but with in­creas­ing dif­fi­cul­ties from the mid to late thir­ties on­ward. The suc­cess­ful preser­va­tion of oocytes by vit­ri­fi­ca­tion will pro­vide the ‘‘ag­ing’’ woman who has had to de­lay her child­birth, for any rea­son, the op­por­tu­nity to con­ceive and de­liver us­ing her own oocytes at the time she de­cides.

So­ci­ety dic­tates the wide­spread use of med­i­cal ad­vances, and so­ci­ety is seem­ingly presently in­tent on women de­liv­er­ing at later ages. The laws of the coun­try will dic­tate the age limit up to which ET may be per­formed af­ter the fer­til­iza­tion of pre­vi­ously vit­ri­fied oocytes in the same way that the age limit af­ter ovum do­na­tion is ap­plied. While ovum do­na­tion has been highly suc­cess­ful in pro­vid­ing a so­lu­tion for women with in­com­pe­tent oocytes, the pref­er­ence of us­ing their own ge­netic ma­te­rial is over­whelm­ing. Le­gal, eth­i­cal, and lo­gis­tic prob­lems of ovum do­na­tion may also be over­come with the use of the sub­ject’s own vit­ri­fied oocytes.

The author Dr Atreyee Chat­ter­jee is the Chief Em­bry­ol­o­gist at Genome, Kolkata

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