The technique is designed to recreate the essential elements of the experience of living in the womb. Human babies, according to Karp, are born less-developed than other mammals. The first three months of life Karp calls the "fourth trimester". Karp believes there is a "calming reflex" that causes babies to instantly relax when they are given clues that they are safe inside the womb. There are five parts of the technique he calls the "five S's".

1. Swaddling: Tight swaddling recreates the confinement of the womb.
2. Side/Stomach position: Holding the baby on the right side slightly face down.
3. Shushing: Karp uses a loud "ssh" sound similar to the loud white noise that is present in the womb.
4. Swinging (and jiggling): Gentle but constant jiggling (especially of the head) is intended to remind babies of the constant motion they experienced in the womb.
5. Sucking: Karp also recommends the use of pacifiers.

CBS news reports that "Critics say Karp is riding to fame on the strength of his patients' VIP parents, who include Michelle Pfeiffer, Pierce Brosnan and Madonna. Endorsements from several stars appear on his book jacket and video cover." Some doctors have also expressed concern that babies may accidentally be left to sleep face down, a position which increases the risk of sudden infant death syndrome. Karp explicitly warns parents not to leave babies in this position.