I refer to the report Freezing Hope (March 31). I believe many people have not studied egg freezing carefully and are unaware of the myriad side effects, and may arrive at hasty and erroneous conclusions. I would like to make the following clarifications.

The egg is not perfectly preserved through current freezing techniques. The egg is the largest cell in the body, with a high water content. This results in more icicle-like structures when frozen, causing cell damage.

To avoid this, high concentrations of cryoprotectants are used to dehydrate the egg. However, cryoprotectants harden the egg shell, preventing the sperm from naturally fertilising the egg.

In the body, the egg is naturally surrounded by a cloud of cumulus cells. These act as a sperm-selection filter to allow only healthy sperm to pass through to reach the egg to fertilise it. During egg freezing, however, these cells are mechanically stripped off to determine the suitability for freezing.

The preservation of eggs is not 100 per cent guaranteed. If eggs were frozen at absolute zero (-273 deg C), then every atom would come almost to a standstill and could be indefinitely preserved. However, the eggs are stored in liquid nitrogen, at -196 deg C. This means atoms and molecules in the egg are still moving but slowly. And the egg continues to age slowly.

The freezing process affects gene regulation and developmental competency. A recent study showed that freezing decreased early embryonic development rates in animal models, as well as the maturation rates of immature human eggs.

I believe there is a misconception that technology and fertility methods can fully make up for delaying childbirth.

It is worth noting that, especially in Singapore, we try to give our children the best start in life, providing for them materially and financially, but it seems that we have overlooked providing them with the best possible start from their very beginnings.

Natalie Lim Sheng Jie