There are an exceedingly few humans that can live on their own, providing they can make themselves clothing, shelter, and fire in short order, as even people in the tropics require such lest they die of exposure or disease as a consequence of. Same with food, and those rare few require the quick making of tools or they will starve.
Pound for pound humans are the weakest creatures on Earth - even a worm can push through dirt with its soft body, as can the tiniest seedling. Try that without gloves and a trowel, and a person'll be bleeding within a few inches of making a scrape.
But even within the airconditioned, food and provisions for cheap, protected mega societies most people live in, humans have the longest childhood of any animals, and the weakest offspring - call it an infant, baby, or whatever silly title sematics offer to convenience an argument - this side of bee larvae. Even marsupial offspring who are born far less developed than placentals can climb from birth canal into the pouch and to a teat.
Have mommy unplug the cell phone and not bring any Hotpockets upstairs and Jr won't make it through the night.
So that nils the "unsupported" argument save for some hunter gatherers still in the Kahlahari or Amazon who still require fire, tools, and donated American tee shirts.
As for pain, fact is human not-yet-baby-thingiez at an early stage DO respond to such stimuli in a manner that adults respond to pain - remember, not too long ago infants "did not" feel pain so required no anesthesia for medical procedures, nor did the insane, as well as woman and slaves, and, well, anything that wasn't a property owning English speaking Protestant male.
Regardless, pain is nothing more than a reactive sensation to potentially dangerous threats as they get too close, and in the case of abortions - feel it or not here it comes - to its most lethal end. Cloroform used while murdering exonerates murderers said no one ever, save a serial killer or three...
Most spontaneous abortions, or miscarriages, occur in the earlier stages of development and thus often without anyone aware. In cases that they are, measures are taken to prevent them.
Diethylstilbestrol was prescribed to prevent them till that was discontinued in 1971 due to various health issues including cancer and even miscarriages, plus it didn't even work.
It seems Jill Filipovic is too young to have heard of this.
No one is pretending a fertilized egg is a human, it IS, hence why abortions are done.