'''Basic Trope''': An unwanted baby is placed on a doorstep for the occupants of the house to raise.
* '''Straight''': Bob's mother leaves him at the doorsteps of his aunt and uncle's home.
** Babies are piled on the doorstep, resulting in a WaveOfBabies when the door is opened.
** Every doorstep in the neighborhood has an abandoned baby on it, and no one thinks that anything is out of the ordinary.
* '''Downplayed''': The new parents of Bob know they'll be adopting a baby and greet his mother or a social worker at the door with Bob.
** Bob's parents can't afford a baby, and there is no orphanage in town.
** Same as above, except the parents simply don't want a baby.
** Bob is an adult and can no longer take care of his aging mother, so he leaves her on someone's doorstep.
** A mother leaves the baby on her own doorstep, in hopes that someone else will take it.
** Someone goes door to door asking for unwanted children.
** Becky needs help getting pregnant, so she sits herself down on the nearest doorstep and waits.
** Bob's mother leaves him at the doorsteps of his aunt and uncle's home...before they arrive back home, Bob is stolen by a thief.
** The doorstep is a church or orphanage and it is understood in that town that babies left there have been surrendered for adoption.
* '''Double Subverted''':
** The thief changes his mind and leaves Bob on another doorstep.
** But then another baby is left at the door of a house.
** The kindly parents take the infant in. The next day, a dozen more babies of different species are waiting for them on the doorstep.
** Bob's parents celebrate "[[FictionalHoliday National Baby-Swapping Day]]": they leave Bob on another couple's doorstep, and the other couple gives their baby to Bob's parents in the same way.
* '''Zig Zagged''': The baby is sick, but is healed, but gets sick again when it isn't on the doorstep, and gets thrown out for being too much of a hassle, whereupon it gets sick again.
* '''Averted''': No babies are left on doorsteps.
* '''Enforced''': "If they just find the baby in the open, they may assume it's just lost. If the baby's on the doorstep, people will understand it was left for them to find."
* '''Lampshaded''': "What the? I don't remember placing a baby on my doorstep. Someone must have left it here."
** A [[LawOfInverseFertility desperate, infertile couple]] puts a sign up on their door requesting foundlings.
** The father kidnaps the baby and places him on the doorstep.
* '''Exploited''': Someone who wants to adopt a child attempts to encourage people to abandon babies on their doorstep, not someone else's.
** The mother abandons the child where she knows it will not be discovered.
** The baby is put up for adoption the normal way.
** The mother knocks on the door, and hands the baby directly to the couple.
* '''Discussed''': "Anything on the doorstep this morning? Milk? Newspaper? Baby?"
* '''Conversed''': "Why do so many babies get abandoned on this show?" "I guess it's better than [[GoodGirlsAvoidAbortion killing]] [[InfantImmortality them]]."
* '''Deconstructed''': The baby is very sick and malnourished.
* '''Reconstructed''': The baby is reared back to health.
* '''Played For Laughs''': The first house has a sign on the door which reads "no babies please". The mother has to stop by twelve more houses before finding one without such a sign.
* '''Played For Drama''':
** The baby dies of exposure.
** The owners of the house raise the baby as a SexSlave.
Please, kind sir, won't you take this child back with you to DoorstopBaby?
%% Optional items, added after Conversed, at your discretion:
%%* '''Implied''': ???