Dame Valerie Adams and husband Gabriel Price are expecting their second child next April.
The double Olympic shot put champion told NZME she was thrilled with the timing, which allows her the best opportunity to recover and compete at the Tokyo Olympics before her retirement.
The couple's first child, daughter Kimoana, celebrated her first birthday last week.
"It's a dream come true to have a sibling for Kimoana," the 34-year-old Adams said.
"People might think I'm nuts, but I'm expected to be menopausal by age 43, so we wanted to have another baby as soon as possible."
As with Kimoana, the couple engaged fertility treatment for this baby.
"We hadn't realised there was an issue trying to conceive, until we tried for a family.
"It's more common than people think, and shouldn't be taboo because help is out there. Knowledge is power, so you can plan to make it happen. We had some embryos in a freezer, and were blessed having one stick."
Adams expected two children to make life "full on".
"But one thing we have this time around is time. I only had six months from having Kimoana until competing at the Commonwealth Games [in April].
"After having a C-section and being a first time mum I didn't know what to expect with the sleepless nights and everything, but this time we have a blueprint. We'll have a plan in place by December next year to be in Europe and building towards Tokyo. I want to have my family watching there."
Adams said becoming parents was her and Price's priority after the 2016 Rio Olympics before she returned to the sport. If the three-time shot put medallist is selected for Tokyo, she will join Barbara Kendall as the only other New Zealand woman to feature at five Games.
"People might think I could wait [to have a family] until after Tokyo, but I didn't want to miss the opportunity and regret it, because after retirement who's going to be there? My family.
Adams said parenthood had taught her one thing above all else.
"Patience… and that not everything is about me any more. I give myself more time to do things, especially if we're about to go out and Kimoana craps her pants. That's an immediate half-hour delay, so you stop and do what you've got to do. It can be a two-person job.
"We both rush in, but that's the reality you live in. Sometimes people forget that when they look at picture-perfect lives on TV.
"I want to continue to inspire women who want a family and a professional sporting career."