Many women have little idea of how significantly their chances of conceiving decrease with age.
Celebrity mothers who have babies in their 40s often do not disclose that they used donor eggs, giving the impression that conception over 40 is easy, said In Vitro Fertilisation experts.
A study, presented at the European Society of Human Reproduction's annual conference in Lisbon, stated that about 24% of 38-year-old women receiving fertility treatment successfully give birth.
But by the age of 44 that success rate dips to 1.3%. Thus, a woman of 38 is 18 times more likely to conceive than a woman just six years older.
The 12-year study led by Hospital Universitairo Quiron-Dexeus in Barcelona, Spain, involved 4000 women. The lead researcher, Dr Marta Devesa, said women should be encouraged to start trying for a family at a younger age.
She added: "But if you can't change society then we should encourage them to freeze their eggs by 35."
Michelle Rijsdijk, an embryologist at the IVF Fembryo lab in Port Elizabeth, said even while women might give birth at the age of 40, as her own aunt did, those women had usually given birth before.
She said: "The likelihood of having a first child at 39 or 40 is rare."
Rijsdijk said while newspapers carry stories of a woman giving birth in her 60s, "the stories never explain that the people that are having babies after 40 are usually using donors eggs; it is not their genetic material".
She added that very few women in South Africa chose to freeze their eggs.
Rijsdijk said that of the roughly 200 women who did so at her facility in Port Elizabeth annually, half were in their twenties and undergoing cancer treatment. Chemotherapy and radiation can affect fertility.
The other half were single women in their early 30s.
"It is rather expensive and women in their 20s don't have R 30000 lying around to do it," she said.
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