I was responding to your observation that

some births result in stillbirths and some result in fatal deformities

Which I took to mean fatal deformities that are apparent at birth and usually cause death soon afterwards. As when a child is born with some or many of their internal organs and structures on the outside rather than on the inside of their bodies. Which in the days before routine fetal scanning and genetic testing in utero used to happen a lot more than today.

I wasn't talking about fatal deformities that would/will lead to premature death at a later point, such as cystic fibrosis or severe combined (primary) immune deficiency and all the other fatal genetic conditions that are present at conception and birth but which usually or often result in death well after birth and the neonatal period.

I was working off your prior exasperated statement that

if some births result in stillbirths and some result in fatal deformities and some result in the baby never even forming etc. then clearly human reproduction IS a spectrum.

I wasn't saying my own view is that human reproduction really is a spectrum, nor was I making this out to be your actual view. Which I think I made pretty clear.

Continuing on with this theme, no most human fertilizations/conceptions do not really have results that are, as you say, "so unpredictable."

About half of the human eggs that get fertilized inside a female human body die within the first trimester, which is why women who learn they are pregnant before then have always been advised to keep news of the pregnancy largely private until the 12-week mark. Most of the other half of human eggs that get fertilized inside a female human will result in a pregnancy that results in a human fetus developed enough to survive outside the mother's body.

Yes, some human eggs fertilized within female bodies will result in second- and third-trimester miscarriages and stillbirths, and some babies born at term will have genetic conditions that will be fatal sooner or later. But still, the vast majority of eggs fertilized in a female human body that survive past the 12th week in utero won't end up in miscarriage, stillbirth or death in the moments or hours after birth. This means most human eggs that get fertilized either die early on or lead to live births and surviving infants - which is very binary.