|World Athletics Championships|
|Venue: Beijing National Stadium, China Dates: 22-30 August|
|Coverage: Live on BBC TV, Red Button, Radio 5 live, online, mobiles, tablets and app. Click here for full details.|
Olympic heptathlon champion Jessica Ennis-Hill said leaving son Reggie at home to compete at the World Athletics Championships in Beijing was "one of the hardest things" she has done.
Briton Ennis-Hill, 29, is preparing to compete in the championships, which begin on Saturday, after giving birth to her first child in July last year.
"I want to make it really worthwhile and make him proud as well," she said.
She added recent doping allegations surrounding athletics are "depressing".
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Ennis-Hill has competed sparingly since winning Olympic gold in 2012, but returned to London's Olympic Stadium to compete in three events at the Anniversary Games in July.
She starts her World Championships heptathlon campaign in the 100m hurdles at 02:00 BST on Saturday.
"I was quite sure I wanted Reggie to stay at home," she told BBC Sport. "I didn't want to bring him all the way here, it is quite a long flight, with the smog and the climate.
"At the same time, it is so hard, being away from him for this amount of time.
"That morning when I left him was one of the hardest things I have ever, ever done. I was overcome with emotion, it is really, really difficult."
The build-up to the championships has been overshadowed by accusations of widespread doping in the sport.
The International Association of Athletics Federations (IAAF) has defended its record on doping.
|Denise Lewis, Olympic heptathlon gold medallist|
|"She would not have put herself on the line if she didn't think she was ready, we saw enough at the Anniversary Games.|
|"She will be disappointed to come away without a medal but she has to be in it.|
|"You are a long time from retirement and to miss a championship because of a little bit of uncertainty would be a shame because I think she is good enough to challenge for a medal."|
Ennis-Hill said it is "really important to get the message out there that there are so many athletes who train incredibly hard" and to "not get caught up in the horrible, awful news at the moment".
She added: "It is hard, it is depressing and it is really sad to read but there are so many highlights of our sport.
"We have to address all the awful things that are happening and make sure we make a change but we also need to highlight the amazing performance of the athletes who train really hard and do true performances."
Watch the World Championships preview show on BBC2 at 19:00 BST on Friday.