A fertility specialist has indicated that men should take diet rich in folic acid and other vitamins if they are trying for a baby.
What's more, men should stop smoking, reduce coffee and alcohol intake if they are planning for a child.
Anne Clark will take to the Fertility Society of Australia's three-day meeting, starting in Brisbane today.
A study of almost 800 men who presented to a Sydney assisted reproduction unit found a "staggering" 59 per cent had nutritional deficiencies, including lower than normal levels of folate or vitamin D.
Clark, Fertility First medical director, said a similar number of the would-be fathers had high levels of damaged sperm, a key factor in infertility normally associated with infection, advanced paternal age or smoking.
According to the researcher, 123 volunteers agreed to make lifestyle changes and to take dietary supplements for two to three months before starting fertility treatment.
Of those, almost three-quarters had a significant reduction in the number of damaged sperm and 36 achieved a pregnancy, including 18 without using assisted reproduction technologies, the research found.
None of the 36 pregnancies miscarried, despite almost a third of the men's partners being aged 38 or older.
"Thinking about getting pregnant is a combined project. Fertility is a couple issue, it's not a woman's issue," the Courier Mail quoted the expert, as saying.
"The traditional sort of foods that we ask women to eat to improve their chances of having a healthy baby, men need to be told the same. They make up half the baby, so they need to be making changes, too," the expert added.
Damaged sperm not only reduce a couple's chances of getting pregnant, but miscarriages are more common and babies are more likely to be born with genetic diseases, Clark said.