"I think it has more to do with the mental shift that occurs when you become a mother; you have much more focus when you run, and you don't take the time you have away from your kids for granted.

"There may be some truth to the 'pregnancy hormones' argument, but for most mothers, having a baby is not going to help your running. You can't train, you're exhausted, you may have had major abdominal surgery. I've had three C-sections and I can still feel it when I run," she says.

"Whatever hormonal boost I may have had, it's definitely worn off by now."

Another driver is the sheer beauty of Hong Kong's trails. McNaughton, who recently returned to part-time work in the finance industry, had always run "just to have fun and keep in shape" but discovered trail running three years ago.

Enamoured, she began training for her first Oxfam Trailwalker. Three weeks from the start she discovered she was in her early stages of pregnancy.

"After discussing it with my obstetrician, learning it was low risk and given how much training I had put in, I decided to go for it," says the New Zealand native. "My daughter probably holds the record for having run the Oxfam Trailwalker as an 11-week-old fetus."

She is sponsored by Gone Running, a local online trail-running store.

"You simply can't replicate the VO2 max [a measure of fitness] benefits you get from pushing up a big hill. Then there's the way you learn to handle pain: you're constantly breaking through a personal pain barrier then recovering," she explains. "In some ways, it gives you the strength to be a better mother."

It just makes me feel guilty. When I run, I just think about running.

Even when I was road running I was competitive. I've always wanted to do better than the person next to me and I've always wanted to better myself. I don't think that's changed. I don't think I'm a "good" runner now, I think I've just found something I'm really passionate about.

it's changed the entire way I approach it. I ran a marathon recently with no specific road training in 3 hours 17 minutes. When you've run 100 kilometres, you're not so afraid of a measly 42-kilometre race any more. There's a variety to running on the trails that keeps you interested and makes you better.

and, of course, because of the help you can get in Hong Kong. Time-wise, my husband and I are a tag team on the weekends; I usually train in the mornings and he usually plays rugby in the afternoon. On Sundays he supports me at the races and it's usually a family affair, with the whole team coming along.

in Hong Kong is that you can train at night and it's safe to run; there are lots of trails and they're generally accessible. It's great because I know the kids are asleep in bed. I usually run guilt-free at night twice a week.

On Fridays when my daughter does her own fitness class I bring my sneakers and go for a run. I'm the mum that picks up her daughter all sweaty.

I eat a lot, I talk a lot and just enjoy myself. You hear about people who run 50km on one small gel packet, but I just can't do that. Perhaps my biggest competitive advantage is my skill at napping - I've perfected the art of a 15-minute power nap.