Between the second and third series. Seriously. you couldn't figure that out for yourself?
Leafpool had her kits in the book "Sunrise," which is the sixth book in the Power of Three series of the Warriors series by Erin Hunter.
Leafpool has kits with Crowfeather in the book "Sunset," part of the Warriors series by Erin Hunter. The kits are named Jaykit, Hollykit, and Lionkit.
Leafpool and Crowfeather had kits between the second and third series.
Squirrelflight did not have any kits of her own. She raised Leafpool's kits, Jayfeather, Lionblaze, and Hollyleaf, as her own to protect her sister's secret that she had broken the warrior code by having a litter of kits.
No because the kits are Crowfeather's and Leafpool's and Ashfur never fell for Leafpool
Spoiler Alert!!!Leafpool has kits with Crowfeather of WindClan. Her kits are named Hollykit(Hollyleaf), Lionkit (Lionblaze), and Jaykit (Jayfeather)
Leafpool had 3 kits; Hollykit(leaf), Lionkit(blaze), and Jaykit(feather)
yes
before The Sight
Leafpool and Squirrelflight went out of camp together and found a save place for Leafpool to have her kits. They had to wait until the kits were strong enough to travel back toward the clan and because no other cat then Squirrelflight was with Leafpool when she kitted, it was easy for Leafpool to say that the kits were Squirrelflight's. There were some questions of course about it, but the clan believed them.
In the book "Eclipse" from the Warriors series, Leafpool becomes pregnant with Crowfeather's kits. She struggles with the conflicting duties of being a medicine cat and a mother, ultimately deciding to give up her kits to raise in ThunderClan without them knowing she is their mother. This decision causes Leafpool emotional turmoil throughout the story.
Sandstorm's kits are Squirrelkit (Squirrelflight), and Leafkit (Leafpool).
Firestar and Sandstorm had their kits sometime between the end of the first series and Firestar's Quest.