As thousands of dads celebrate Father's Day, many others who haven't been able to have a child are questioning what can be done to help them.
An Auckland research programme is hoping to find out more about the link between men's lifestyles and increasing infertility.
No topic is off-limits on radio DJ Dom Harvey 's breakfast show but under the laughs he faces a very serious issue. When Harvey had a tumour removed a couple of years ago, a complication left him infertile.
"Right through your twenties one of my worst fears was actually getting someone pregnant and having a baby that I didn't want. Now Jay Jay and myself are at a point in our lives where we think we'd be great parents and we really really want to start a family and it's... bloody difficult," Harvey says.
He is supporting the Nurture Foundation - a charity funding research into men's fertility.
There are a range of environmental factors associated with life in the 21st century which may have an impact on men's fertility such as delayed parenting, smoking and even the heat and radiation from appliances such as laptop computers, cellphones in pockets and microwave cookers.
But the Auckland research is focussing on one other factor - body weight.
"In recent years there has been just a little bit of evidence to suggest that a man's body mass index, particularly if it's very high, could have an adverse affect on a man's sperm quality," Auckland Hospital fertility specialist Neil Johnson says.
Researchers hope to test 1500 men, first by taking their body mass index and then by scrutinising their sperm sample for size, shape and structure.
"It's an additional piece of the jigsaw of piecing together the impact of lifestyle and bodyweight on men's fertility," Dr Johnson says.
