These two words are often confused with one another. Since I know a lot of people in the childbirth field, I see these words a lot. Not even all the birth people use them correctly, which surprises me a bit.
A breach is a gap in something or a violation of something. To breach something is to break, break through or break open something.
They were in breach of contract.
The enemy attempted to breach the castle walls.
A breech is the back or lower end of something.
The baby was breech; the midwife could see his bottom emerging first.
Yes, there is only one letter difference between these two words, but as you can see, they mean completely different things. Granted, you could use breach in reference to birth, but it certainly wouldn’t mean the same thing as a baby being born bottom first.
The obstetrician created a breach in the mother’s belly when he performed the cesarean.