Looks like we're going to have to go into some science for dumbasses.

Pain is perceived differently based on the person due to different nerve connections and different chemicals the brain sends out. This is commonly referred to as pain tolerance and this means that EVERY person feels a different amount of pain. Being shot for one person may be a walk in the park compared to the agony another feels.

Length is also to be taken into account. Birth and labor can take days, with the pain maintaining constant until the child is born. Recovery also takes days to weeks depending on the method. The average healing time is 6 weeks. During these weeks the pain will persist.

While balls do swell up, they will not hurt as bad as the initial pain in the days afterwords. The average healing time is a week to two weeks. During these weeks the swollen pain persists.

This unit is measured from the brain. When more blood flows to the brain, pain is assumed to be present. But it will not stay the same for each person, and each person will feel differently due to the aforementioned reasons. Therefore, something measured as "57" on one would ranged from "1" to "100" on a different person.
In addition, pain is not well enough defined to use something like that.
That picture was obviously made to get women to stop using childbirth as an argument. Which they should, but that doesn't make the picture right.

We can not tell which is worse, due to length, differences in pain tolerance, and the fucked up way they use that measurement.