More accurately, "additional blob"

Can confirm, that is an actual word we use in Norway, and yes, the translations are more or less correct

My husband and our youngest son are 'afterblobs'. My husband was born 14 years after his siblings, and our youngest was born 10 years after his sibling

The Swedish version is "sladdbarn" but with all the double meanings in the language that could be translated as "skid kid" or "extension cord baby".