Women should ensure they have exhausted all options before resorting to IVF, according to international experts concerned the procedure is being over-used.
They say the value of IVF (in vitro fertilisation) for women with blocked tubes or for infertile men is not in dispute.
However, the risks could outweigh the benefits in other cases such as unexplained infertility, moderately low sperm count or endometriosis.
Unexplained infertility accounts for up to 30 per cent of cases, they write in an analysis published by the British Medical Journal.
However, some of these couples might have conceived naturally if they had waited, ideally at least three years.
A concern is that national fertility registries in many countries, including Australia, do not collect data on duration of infertility.
"In Australia and New Zealand about one in 30 babies is conceived by IVF," says co-author Professor Ben Mol from the University of Adelaide.
In Denmark it is one in 20 and in the Netherlands it is one in 40.
"The issue is that we have a lack of knowledge of what the correct ratio is or who should have the procedure when," says Prof Mol.
One million babies were born in the first 25 years of IVF until 2003. The number soared to two million by 2005 and reached about five million by the end of 2013.
The authors argue that evidence for the extended use of IVF is weak and could be detrimental to the long-term health of the child, particularly as a result of multiple births from the use of two or more embryos.
However, Prof Mol points out that multiple births are not an issue in Australia, where the use of single embryos is the norm.
He says the risks are low for singleton babies.
"We are sure IVF is appropriate for couples who have been trying to get pregnant for three years or longer."
The authors question whether a profit motive is leading to a lack of will to question the use of IVF.
"In younger women with no obvious cause of infertility, IVF is not cost effective within three years of trying to conceive," they write.
"As a society we face a choice. We can continue to offer early, non-evidence based access to IVF ... or follow a more challenging path to prove interventions are effective and safe.
"We owe it to all subfertile couples and their potential children to use IVF judiciously and to ensure that we are first doing no harm."