Our wonderful and frankly miraculous bodies are designed to give birth. The shape of the pelvis, cocktail of hormones and powerful muscles of the uterus are designed to all work together perfectly to bring our baby into the world, if we let them do their job! *That's not to say that medical intervention hasn't got its place, in some circumstances it is needed.
What gets in the way? Fear and being observed. Fear disturbs this natural process by inviting the hormone Adrenaline to crash the party (literally). We then go into Fight or Flight mode, and the Oxygen is no longer where it needs to be, fuelling the muscles of the uterus. Feeling calm and relaxed on the other hand produces Oxytocin, the love hormone or feel good hormone which fuels labour and gets everything working as it should.
Think of your pregnant cat for a minute - where is it most likely to give birth? Usually not in that nesting box you made especially (annoyingly!), but more likely under a bed or in a cupboard corner i.e. in a safe place, unobserved, somewhere private and comfortable. We have the same instincts.