What is SLED?

SLED is an acronym for Size, Level of Development, Environment and Degree of Dependency.

The SLED Test is truly invaluable when trying to persuade and defend your Pro-life views to others.

This method was first developed by Stephen Schwarz in his book The Moral Question of Abortion.

The unborn differ from toddlers in only four ways:

  • SIZE



Level of Development




Degree of Dependency


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Size and Appearance

The unborn is smaller than a toddler, but toddlers are also smaller than teenagers or adults. It’s true that embryos and fetuses are much smaller than a newborn baby. It’s also true that during different stages of development the preborn might not look like what some would consider a “normal” human being. But at all stages of their development, the preborn are still human beings that look exactly the way every other human being has looked at that particular time in their development  They still have the same DNA and genetic makeup as they will when they are toddlers, teens and adults.

Questions to consider: Do humans lose value when they don’t look right? Does size equal value? Are husbands more valuable than their wives? Can men oppress women just because women are generally smaller than them? Are preschoolers less valuable than teenagers because they’re smaller?

Size and appearance do not determine personhood.

Level of Development

The unborn is less developed than a toddler, but toddlers are less developed than teenagers and adults and yet still human. Embryos and fetuses are not as developed as an adult but again what difference should this make?

Questions to consider:  Is a person’s value defined by her abilities, by what she can or can’t do? Do we forfeit our rights as human persons—our claim to life, liberty, and the pursuit of happiness—because we don’t have the capabilities others have? What if we could no longer play chess, run bases, read, or remember? Many disabled adults are less “developed” than many newborns, but that hardly justifies killing them. Do stronger, more capable,more intelligent people have more rights than others? Do human beings become disposable simply because at their level of development they are helpless, defenseless, and dependent? Is a four year old girl less valuable than her mother because she can’t reproduce?

Personhood is not determined by level of development and abilities.


Baby Rachel (Rachel Caruso) was born prematurely at 24 weeks, in the middle of her mother’s second trimester. On the day of her birth, Rachel weighed 1 pound, 9 ounces, but dropped to just under 1 pound soon after. She was so small she could rest in the palm of her daddy’s hand. She was a tiny, living, human person.

Heroic measures were taken to save her life because she was a vulnerable and valuable human being. If a doctor had killed Rachel while she quietly slept at her mother’s breast, we would have recoiled in horror at this homicide. However, if this same little girl—the very same Rachel—was inches away from the outside world, resting inside her mother’s womb, she could be legally killed by abortion. Here’s the question: If we are valuable human persons, do we cease being valuable because we move locations by crossing the street, moving from the kitchen to the den, or simply rolling over in bed?

If it’s wrong to kill an innocent human child at one location, then it’s wrong to kill that same innocent human child located six inches away. If it is considered homicide to take the life of any child like little Rachel outside her mother’s womb, then why is it legally protected to take the same life for the same reasons at exactly the same stage of development while inside her mother’s womb? Nothing changes except the child’s location.

Location has no bearing on personhood.

Degree of dependency

The unborn’s dependency on his mother for biological sustenance is irrelevant to the baby’s value. No baby is “viable” if degree of dependency matters because babies of all ages depend on their mothers for feeding, whether via blood (an umbilical cord), breast, or bottle. In this sense, no child is “viable” even years after she’s born. Human beings may be dependent on others for their survival, but they aren’t dependent on others for their value. All physically dependent people are at risk if degree of dependency determines their value. If dependence on an external source makes one non-human, then all those dependent on kidney machines, pacemakers, and insulin would have to be declared non-persons.

Dr. Bernard Nathanson—formerly one of the largest abortion providers in New York City and an original founder of NARAL (National Abortion Rights Action League)—now points out as a prolifer that there is no ethical difference between an unborn child who is plugged into and dependent upon her mother and a kidney patient who is plugged into and dependent upon a kidney machine.

Personhood is not determined by dependency.

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