The new research on fertility struggles shows that 60% of 1386 couples who tried for a year or more to conceive had successful pregnancies, and about 50% of them did not need medical treatment like IVF (in vitro fertilisation).
If couples were able to have their first child without fertility treatment, their chances of having more children naturally were high, the research showed.
Sally Marr said her two children Leo and Sadie were conceived through IVF. She would have tried to have children earlier if she had met her husband Andrew when they were younger.
The couple had been through five rounds of IVF and she would not advise young couples to rely on IVF as a ''backstop'' for when they were older.
Mr Marr said while he would not necessarily advise young couples to have children simply because they were most fertile, he thought young couples who knew they wanted to have children in the future could consider measures such as freezing eggs in their 20s.
Mrs Marr said she would encourage both of her children to have children while they were young.
Research lead author Dr Antoinette Righarts said 62% of couples ended up having children, and 50% of live-births happened more than two years after couples first sought medical advice about conceiving.
Age was the most important factor for couples struggling to overcome infertility and have more than one child, Dr Righarts said.
Senior author Prof Wayne Gillett said conclusions from the longitudinal study showed if couples did not have a major problem causing their infertility, or a long time of infertility, the situation should be managed without treatment initially.
The findings of the research confirmed couples who wanted children should not delay trying to start a family if it ''suits their personal situation'', particularly if they wanted more than one, Prof Gillett said.
The research was published in the Human Reproduction journal.
