Not when "convenient", necessarily, but when the question of a woman's autonomy and control of her body is the central issue.
Up until poor women could get abortions without great risk and suffering, and even from then until recently, the standard practice of all the current pro-life people was to discard first and second trimester miscarriages as garbage - without even checking to see if they were alive.
They were flushed down the toilet at home, incinerated with the rest of the medical waste in hospitals, refused baptism or religious ceremony or burial in church graveyards, and not recorded as human deaths in any of the official records civil or religious. That went on, unremarked and unexceptional, for hundreds of years.
Meanwhile, among the many examples of such stance and statement from a prolifer, a political representative of the prolife faction - one of the people publicly espousing prolife views and legislation and so forth - explained a couple days ago why the legislation he and his crew were intending to fight all the way to the Supreme Court did not "protect" in vitro human embryos: they weren't in a woman. No woman was involved.
The game was given away from the beginning.