"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]."