The breath child (that lets you release your breath when it's born) is a son. Nowadays it's cool to have a girl, but back in the day you wanted a son to carry on your underwater basket weaving legacy. That's why this is a son.
The reading of this is messed up. 子 is こ, that should be okay. 息 is むす for some reason though. Why? Because you gave birth to a son, but he was a moose (むす). You better hold that breath again, because this is not what you wanted.
Tonight is very quiet because my son is cramming for the exam tomorrow.
My son works efficiently and goes home earlier than anyone else.
I have the most beastly son. He sneakily ate up the rest of my cake last night.