The episode where Kif gave birth was Kif Gets Knocked Up a Notch (2003), which aired January 12, 2003.
Tardigrades are micro-animals on Earth and are known colloquially as "water bears". At 0.5 millimeters long they are right on the boundary of being microscopic, they are also very unique in several ways. They don't fit into any standard classification of animal and are only distantly related to arthropods, they can be found in every region in Earth's biosphere from mountaintops, the deep sea, tropical rain-forests, to the Antarctic. They are also among the most resilient animals known, being able to survive extreme conditions no other animal could survive like extreme temperatures and pressures (both high and low), they can survive for extremely long periods of time with no oxygen, including in the vacuum of space, without water or food and can even survive prolonged exposure to radiation levels that would kill most organisms in seconds.
The role of Amy's father, Leo Wong, originally voiced by Billy West, has been recast with an Asian actor: Feodor Chin.
When making Fry's candy the Professor tries some and passes out due to a diabetic coma. Fry says they better add more sugar to increase the sweetness and Bender then adds a little treacle. Treacle is a type of syrup made during the refining of sugar, the most common forms of treacle are golden syrup, a pale variety, and black treacle, a darker variety similar to molasses. Black treacle has a distinctively strong, slightly bitter flavor, whereas gold treacle is more sweet and has the appearance and consistency of honey, it is a common sweetener in British cuisine like tarts and pudding.
The title of the episode is named after Mark Medoff's book "Children of a lesser god"