Longest Pregnancy Ever

"Okay, first of all, Bonnie, you've been pregnant for like six years, alright, either have the baby or don't!"

- Peter Griffin, Family Guy

Thanks to the nature of storytelling in visual mediums, one day of in story can take weeks or months to portray (depending on the medium). As a consequence, pregnancies that are of the standard 8-9 months look like the characters have been pregnant forever.

Then there's times where the decompressed nature of such stories gets leaned on and outright abused.

Things like Comic Book Time and Webcomic Time can make a pregnancy last years in real time; to the point where even the creators (let alone the readers) aren't sure how far along a character is supposed to be in their pregnancy. God forbid a Schedule Slip get factored in, and this trope sometimes leads to the Tethercat Principle if we never actually see the woman deliver or see her again.

Occasionally used as a Running Gag. Contrast with Express Delivery.

Anime and Manga

 * In Naruto, Kurenai Yuhi was pregnant for 4 years until she gave birth, and the child's gender is yet to be revealed (but Word of God says he wants the child to be a girl). This is more because a sequence of chapters that has indeed taken years to come out span a timeline of a month at most in-story.
 * It was also revealed that female jinchuuriki such as have abnormally long pregnancies, generally lasting ten months.
 * One Piece: the father of is a criminal, and The Government is out for blood on all his descendants. The mother   delays the birth for a whole year through sheer willpower alone, so when  is born, his father,, has been dead for a year. This spares  life, but costs his mother hers.
 * A really horrifying example comes in Yami no Matsuei.

Comics

 * In For Better or For Worse, Elly was pregnant with April for about a full year rather than the usual 8-9 months. This was repeatedly Lampshaded by Elly complaining that "The kid's not even BORN yet and they're already making me WAIT!", among other things.
 * During the The Clone Saga, Mary Jane was pregnant for about two years in real time, which matches up with Marvel's time scale, 3 years in real time equals 1 year in the comics.
 * The Queen of Darshan in Lanfeust has been pregnant for 15 months when first seen. Discovering the reason for the unusual length is a minor plot point.
 * Nine Chickweed Lane: Diane has been pregnant since June 2009 - a total padded out by the six-month Whole Episode Flashback that immediately succeeded that reveal. She finally gave birth in October 2011... after going into labor in August and having that padded out with another character's Journey to The Center of The Mind.
 * Baby Blues: Wanda, Bunny, and Yolanda were pregnant with Wren, Wendell John and Wendell Jon, and Dziko. Wanda's pregnancy with Hammie also lasted long, mostly due to Comic Book Time

Film

 * If you measure the passage of time by the American Civil War battles in Gone With the Wind, it turns out that Melanie is pregnant for about 21 months. (This error does not happen in the book, BTW.)
 * Averted in Chicago, where Flynn tells Amos that no one will believe Roxie's child is his because a jury "can count to nine. Can you count to nine?"

Literature

 * The Inheritance Cycle features Elain, who may be anywhere from seven to fourteen months pregnant at the end of the third book. She was pregnant in the first book, and more than a year passed between then and the third book, in which someone mentions that Elain's kid is overdue. She finally gives birth to a daughter in book four.
 * In the Nightside novels, Alex's pet vulture Agatha was pregnant for 20 months and counting. Justified in-universe, as nobody's sure exactly what she mated with...
 * In the original version of Demon Seed, the supercomputer Proteus informs the mother of his child that her pregnancy will proceed more slowly than a normal pregnancy, not more quickly as she had hoped. She's not pleased, especially since Proteus didn't bother with such niceties as asking first.
 * Literal example in The Kalevala: the air maiden Ilmatar became pregnant by storming sea and carried the child for centuries. The kid (better known as the mighty wizard Väinämöinen) was thirty years old when he was born. Might be justified because Wizards Live Longer.
 * Star Wars Expanded Universe: in the Dark Nest Trilogy, Queen Mother Tenel Ka Djo is pregnant by Jacen Solo (son of Leia and Han) and, to avoid any rumours that he is the father, she uses The Force to artificially lengthen out the pregnancy to one year.
 * A side effect of the early anti-aging treatment in the Honorverse is extended pregnancies, typically about 11 months. Later versions of the treatment have normal term pregnancies.
 * In Iain Banks' Excession a character delays her babies' birth due to feeling conflicted about the father, she is heavily pregnant for 40 years. Arguably an inversion as it takes considerably less than 9 months to read the book.

Live Action TV
"Denzil: Seventeen years?! Gwynedd, if you have been pregnant for seventeen years, surely you should have experienced symptoms, like morning sickness?
 * The cast and crew of Lost once lampshaded this with Claire's pregnancy. The pregnancy itself is actually more of an aversion, since she was 8 months pregnant at the beginning of the series and gave birth late in the first season, which covered only about a month and a half of story time. However, in real life, about 7 months passed until the birth episode finally aired. In an earlier-season-one question-and-answer session (which is viewable on the DVD set), someone in the audience asks if she is "ever" going to have the baby, to which they jokingly reply "In season 3 -- she actually gives birth to an adult!"
 * "The Average Family" sketch on Australia Youre Standing In It featured a character who was 23 months pregnant.
 * Ensign Wildman from Star Trek Voyager. She was pregnant before the events of the pilot episode. She doesn't give birth to Naomi until midway through Season 2. Of course, since her husband is an alien, this gets explained by the Bizarre Alien Biology. Ironically, once born, her daughter grows up really fast.
 * In Friends, Rachel is pregnant for at least fifteen months, being already pregnant at Chandler and Monica's wedding (May 15th 2001) and going on maternity leave in August 2002. On the flipside, both Carol and Phoebe were pregnant for about 20 weeks, or about half of what a normal pregnancy is. Phoebe's could be partially justified in that multiple births tend to have shorter gestation periods than single births, but the triplets were explicitly shown to be healthy when they were born, so this was more of a math error than anything, and because of how the show was shot (with most of the new seasons coming in right when the old ones left off) this was hardly the first example of the timeline being off.
 * In Rome, tells  of her pregnancy during historical events that occur around 42 B.C. Judging by other historical events, like the betrothal of Octavian and Livia, she is still pregnant in 39 or 38 B.C. This is reportedly due to the show's cancellation and the necessary rewriting of the last few scripts which stuff about 15 years of history into 8 episodes.
 * Dana Scully's pregnancy in the eighth season of The X Files seems to have lasted about a year, going by the dates.
 * This was lampshaded in a Weekend Update skit of Saturday Night Live. When Tina Fey mentioned that Kate Hudson gave birth to her son, she did so after 15 months of pregnancy (Hudson's pregnancy wasn't exceptionally long, but she was in the middle of promoting a couple of movies, so the large number of photos and interviews of her very happily pregnant made it seem longer than it was.)
 * An Absolutely sketch involving recurring characters Denzil and Gwynedd had Gwynedd revealing she was seventeen years pregnant.

Gwynedd: I did. But I put that down to waking up in the same bed as you."


 * In the British sketch show Alfresco there's a Parody Commercial for private healthcare, in which one woman had a normal pregnancy under private care, but another had to wait so long on the National Health Service that her baby was born as an adult.
 * Sanctuary: Due to a combination of factors, 's pregnant girlfriend can't give birth without a huge risk to herself. Magnus figures out a way to reduce this risk by slowing the development of the fetus, but it also means she will be pregnant for a little under two years.
 * Explicitly defied in How I Met Your Mother: although Lily becomes pregnant in "Challenge Accepted", the sixth season finale (which aired in May 2011), that episode was actually set in September 2011, a couple weeks before Punchy's wedding (which took place in the seventh season premiere, aired September 2011) and she conceived the night of Hurricane Irene (August 27, 2011). Instead of just implying it, the writers take pains to make sure this timing is mentioned in canon: Ted breaks up with Zoey in "Landmarks", the second-to-last episode of season six, and in "Challenge Accepted", mentions that he and Zoey had been broken up for a few months, not the week or so that had elapsed between the two episodes.
 * In Tinsel, Amaka Okoh's pregnancy lasts 12 months.
 * Once Upon a Time: The Evil Queen's Dark Curse stalls Cinderella's pregnancy at nine months for twenty-eight years - once Emma enters town and time resumes properly, Ella is finally able to give birth.

Mythology And Religion

 * It's not remotely a doctrine of any form of Christianity present or past, but attempting to work out when Jesus was born could lead one to conclude that his mother Mary experienced a pregnancy of 10 years. That's because (according to the Gospels) his conception occurred during Herod the Great's reign as King of Judea, and his birth during a census in Cyrenius's reign as Governer of Syria. Extra-Biblical sources date those periods as 10 years apart. However, regardless of its reference to Cyrenius (the correct translation may actually be "before" and not "during"), the Bible does portray Herod as reigning when Jesus was born (whereupon he pulls his infamous Nice Job Breaking It Herod), so its authors clearly don't intend to suggest a years-long pregnancy.
 * In classical Chinese literature, it is said that multiple ancient kings' mothers were pregnant for 2~3 years before the kings were born. Obviously this is made up to make people believe these kings have divine power.
 * The true award goes to the Finnish man called Vainamoinen, who gestated for 700 years- and was born an old man.

Tabletop Games

 * The Book of Erotic Fantasy gives details on the subject of reproduction for all the major player races, noting that elves have a gestation period of fully two years.

Theater

 * Serbian comedy "Radovan The Third" has Radovan's daughter pregnant for five years because her father won't let her give birth until she gets married.

Video Games

 * A retroactive example - At the end of Fire Emblem: Radiant Dawn, The father in question had died three years prior, and the mother had presumably been kept away from him for at least an additional year besides. She also mentions that he had left their homeland 19 years before the climax of FE9, and the condition he was in when she was near him after that left her getting pregnant then... unlikely, to say the least. A slight twist in that  but since this isn't shown to happen with any other  this is most likely a math error.
 * It isn't conclusively shown not to be the case for, either, and they are notoriously long-lived (the paternal grandfather, , is known to be at the very least in his ninth century of life and doesn't look particularly ancient), so it's possible.
 * Sam and Max Freelance Police, in the Telltale Games, has Sybil Pandemik. Her  baby isn't born until the end of the 5th episode of season 3, by which point she's a month into her fifth trimester. In other words, thirteen months of being pregnant. When her water breaks, she also... er, "releases" pennies, to the confusion of the other characters.
 * In The Sims 2, if you save and exit a household while a Sim is pregnant, she will remain at the stage of pregnancy she was at when you did so. So if you go into another household and have another male (or female) kid 'grow' to be an adult while being there, they might meet the same woman, who was always pregnant since he (or she) was a child... Divide By Zero!
 * Notably averted in The Sims 3, however: there's an option to have the world continue around you while you play, so characters will grow up, grow old, get married, have kids, and die, and you might never know (unless you read the newspaper).
 * In Red Dead Redemption, one of the side quests has you help a pregnant woman who was thrown out on the street by the man's wife. If you do not complete the mission until after the Time Skip (which is about 3 years) and talk with her, she is still pregnant.

Western Animation
"Quagmire: It's hard to believe she's already 18."
 * Bonnie from Family Guy was pregnant for the show's first five seasons. Even though the show runs on Comic Book Time, since none of the other kids have aged at all, it's frequently Lampshaded by other characters, since it it took ten years of real time for her to give birth in "Ocean's Three and a Half"


 * Ms. Gloria Duwong from The Weekenders was pregnant for the entire four seasons of the show.
 * Martha Generic from ''Bobby's World' was pregnant for nearly two years.
 * Luanne Platter from King of the Hill was pregnant for almost three years; the strange part was she showed no signs at all until the episode where she gave birth.
 * Fish Hooks: So far, Mr. Baldwin, a seahorse.
 * Marge was apparently pregnant with Lisa for 15-16 months on The Simpsons, seeing how she was conceived in March 1983 and was born around the 1984 Summer Olympics.

Web Comics

 * In Gene Catlow, Tatavania has been pregnant with Michelle from 2003 to the present. Due to one of the more Egregious abuses of Webcomic Time ever, that time span has only been a few months, in-story.
 * In Two Kinds, as of mid-2010, Flora was confirmed as pregnant with Trace's child. But the readers have been clued in that this is the case since at least 2006. As of May 2011, she barely has a baby bump (and we only have Kathryn's word on that). This is another case of chronic Webcomic Time, since only a few weeks have passed in-universe.
 * Order of the Stick: Kazumi Kato has been pregnant for three years worth of strips and counting. In-story it's been an unknown number of months, but probably between 6 and 8.
 * Sabrina Online: Amy was pregnant with her son from February 1997 to January 2000. In-story her pregnancy was of normal length.
 * Anders Loves Maria: Maria was pregnant for nearly all of the comic's three-and-a-half-year run. Though this was padded out by the comic's liberal use of flashbacks.
 * Word of God says that Nei'kalsa Tion Sarghress of Drow Tales is pregnant during this scene, which was published during December of 2007. While only a few months passed in story until a 15 year timeskip in October 2011, this means she was pregnant for almost 4 years of real time. Even knowing that drow are Fae and therefore have Human Outside Alien Inside that's still pushing it.

Web Original

 * The classic web hoax malepregnancy.com dates back to at least 1999 according to the Internet Archive. The subject, Mr. Lee Mingwei, is still described as pregnant as of 2010. That's 11 years.
 * Happens a lot on message boards with people who say "How much drama can I have in my life?" It's "I'm having a baby!" Years later, she's still pregnant.

Real Life

 * This article reports of a woman who had a calcified fetus removed from her body. Apparently she had miscarried the almost full term baby and never passed it from her system. The fetus calcified and remained in her womb for decades before doctors removed it.
 * An elephant fetus takes 2 years to gestate.
 * A number of animals are capable of delayed implantation. For example, the nine-banded armadillo delays for about the same amount of time it takes to gestate (four months).
 * It's actually very possible for a woman to be pregnant for ten or eleven months. Unfortunately, these pregnancies have a high rate of death for the fetus, much higher than an equivalent premature baby, because the baby's head is generally too large to fit through the pelvis.
 * You can just perform a cesarean. Bigger problems are caused by issues such as placenta becoming less active and baby being able to poo in the womb.
 * Trimesters of pregnancy are formally assessed from the end of the last menstrual period, not the presumed date of conception, which typically adds another two weeks to the pregnancy's technical duration.
 * The longest human pregnancy on record lasted 375 days instead of the standard 280 - labour is triggered by a foetus' size and this foetus had abnormally slow growth.
 * It is estimated that a human pregnancy should be about 18 months. We are all born incredibly premature in order to be able to fit the head out at all and avoid killing our mothers in the process. The growth of a baby's brain is far more comparable with fetuses than with babies in other apes, and humans are downright helpless compared to other primates soon after birth.
 * Jackie Chan himself stated he was in his mother's womb for TWELVE MONTHS.