Oggy gets up one morning to discover that his stomach is enormous...it's round...is he pregnant? He can't believe it at first and then, timidly flips through the pages of a magazine for young parents...he is pregnant!
Official Synopsis, 
Episode starts: Oggy in bed, while the Cockroaches use an air pump on his stomach and keep inflating it, until the next day.
The next day, Oggy who has just woke up and starts to brush his teeth notices his belly has grown huge. He then runs to the bathroom and picks up a magazine, saying on the cover 'Mom' and he assumes he is pregnant.
Next, he dreams of having kids. With a mirror, holding his back and even sucks in his belly button after that he goes through the door but gets jammed halfway through and we see the cockroaches laughing at him.
Later, Oggy is eating strawberries, whilst eating, Oggy sees something that looks like it's kicking (probably indigestion) and he thinks that it's his baby/babies kicking. Following that he performs a scan, and sees something, and thinks it's his baby. He then is seen knitting clothes for his baby/babies.
Oggy walks out of the room and the door has gone circular to get his belly through. After he leaves, the cockroaches leap into one of his suits and start dancing.
A day after we see him craving ice cream he is then holding his belly against the mirror then he starts doing exercises.
The next day we see him craving bananas, and he starts sewing pillows; after he's done, he brings the pillow over to a cradle with the cockroaches in it, and he chases after them, but since the size of his belly he is slow after the chase he goes down the stairs slowly. Then Jack comes in and hits the cockroaches with a newspaper and he has a little toothpick in his mouth.
Oggy finally made it down, and Jack watched in surprise. Jack asked what is this. Oggy says there is pop-up news for him. Jack says that there's no pop-up and pops his belly. After Oggy becomes a thin cat and all air is released, Jack gets away. Roach gang laughs like mad and Oggy is very upset, but then he sees the air pump...
In the end he finds the air pump and inflates the cockroaches while they sleep and they float out of his house and into the sky, then Oggy pulls a tongue at them, and then it ends.
- Oggy and the Cockroaches - Nine months and counting (S1E18) Full Episode in HD (published by OGGY on Apr 12, 2016, on YouTube. Accessed Nov 14, 2018.)