Because it is a human being.
Via Life News:
If there is anything abortion activists hate the most, it’s photos of unborn babies in the womb. They reveal the truth about the humanity of the unborn baby in a way that convinces many people abortion is the killing of an unborn child.
Frequent LifeNews author Sarah Terzo highlights one quote from an abortion advocate who doesn’t like them:
From pro-choice author Melody Rose:
“The images and language most often wielded by pro-life advocates are vivid and emotional… recent developments in imaging technique certainly have facilitated a reliance on powerful pictures that humanize the fetus in a way not possible two decades ago. Because fetuses now can be seen in intricate detail, opponents of abortion have striking images to use in support of abortion restrictions, despite what these restrictions might mean to women’s health and freedom.”