Reference for Niddah 57:44

תניא נמי הכי

in a reversed position it is deemed born as soon as its greater part issued forth, but, it follows, if it issued in the normal way the head alone causes exemption. R. Jose ruled: Only when it issued in the normal manner in a condition of viability. And what is 'the normal manner in a condition of viability'? The issue<span class="x" onmousemove="('comment',' Lit., 'when it went out'. ');">³⁹</span>

Jastrow

Jastrow

Jastrow

Jastrow