Is there some official gradation of sins?
Masturbation is a sin.
Contraception is a sin.
Abortion is a sin.
Lusting after your neighbor’s wife is a sin.
Now, I would say that depending on what stage of the pregnancy, an abortion has, perhaps, varying degrees of moral implications - but many Christians don’t make such a distinction and oppose abortion merely because they believe that the bible, as the word of god, says it is a sin.
But they also believe that masturbating is a sin as stated by god him/herself in the bible.
So if playboy magazine has lead to at least 65 million incidents of masturbation, should Hugh Hefner be compared to Mao?