Sometimes the LawOfInverseFertility hits so hard that the woman doesn't even realize she's pregnant, often not until the ScreamingBirth (and sometimes not even then). Cries of "ButICantBePregnant" and "how could I have missed this?" ensue. For whatever reason, when they ''do'' notice before giving birth, it isn't the lack of [[NoPeriodsPeriod periods that tips them off]], but rather the MorningSickness and WackyCravings. It seems that heroines just don't keep track of their monthlies. Cue BabiesMakeEverythingBetter!

This is TruthInTelevision, in several ways.

* When they're near menopause, women's periods can become erratic, making them more difficult to track. Couple this with the fact that menopause takes time and doesn't occur at the same age for every woman, and older women can have an unplanned child whose college years will coincide with their own retirement. Similarly, some younger women can have health issues that make fertility unlikely or erratic. (For example, [[ PCOS]].)
* In many eras, sex education was (and in some places, still is) non-existent or pathetic, and some young women simply ''didn't know'' [[MissConception the details surrounding pregnancy and its cause]].
* Even for young, healthy, well-educated women, pregnancy can end up a surprise. Sometimes implantation of the embryo can cause minor bleeding and the woman can mistake that for her regular period. Read the [[note]]Roughly once a month, a woman's body builds a lining on the uterus to defend against the possibility of pregnancy. Human pregnancies are more invasive than most, a trait shared with other primates, some bats, and the elephant shrew. The shedding of this lining is menstruation. (You may have noticed dogs and cats don't menstruate; in fact they and other placental mammals reabsorb the lining. So do human women, but just not all of it.) The embryo implants in this lining by using enzymes to dissolve a portion of it just a little bit. This can cause some spotting that, except for the amount of material, would be identical to menstruation.[[/note]] for more details. Or possibly the woman, like most women, leads a busy life and doesn't necessarily keep close track of her periods, relying on [[HystericalWoman the warning signs]] to keep from making a mess. And some women keep having periods right through the pregnancy, though this is rare.
* Some methods of birth control "turn off" periods for extended lengths of time, which can make it very easy to miss the fact that a woman is pregnant until she's well along the way. Some types of [=IUDs=] (intrauterine devices) are becoming notorious for this.

Not to be confused with ButWeUsedACondom, but it's likely to be a result. Contrast with MySecretPregnancy, where the mother knows, but keeps it a secret from the world at large. May be justified in the case of a MysticalPregnancy or a MisterSeahorse situation.

'''Beware, all spoilers are unmarked.'''


[[folder: Anime and Manga]]

* ''Manga/GreatTeacherOnizuka'' -- Kunio Murai's mother didn't realize the implications of her sudden weight gain at first.
* In ''Manga/KodomoNoOmocha'' Sana's biological mom Keiko actually didn't know she was preggers ''until she gave birth''. Somewhat more understandable in the manga, where Sana's birth happened when Keiko was 14 (she's still very young in the anime, but not THAT much), and it's strongly implied than Sana is also a ChildByRape and the result of sexual abuse by Keiko's uncle.
* This happens to Shigeru in ''Manga/AkkanBaby'', though in her case it's not so much "ButICantBePregnant" as "how is babby formed?"
* This trope was played tragically straight in ''{{Manga/Berserk}}'', where Guts and a now insane Casca only discovered that she was in her beginning stages of pregnancy after she miscarried their child under the severe trauma that she sustained from the Eclipse [[note]]A few fans believe that Casca might have known she was pregnant before she went insane and either never got the chance to j Guts or [[MySecretPregnancy didn't want to tell him]] out of consideration that he would stay with the Hawks out of duty instead of pursuing his dream[[/note]].


[[folder: Comic Books]]
* ''Comicbook/{{Concrete}}'': neither Concrete nor Maureen, the biologist who studies him, even suspect he's pregnant until [[ChestBurster his back cracks open and there's a smaller him inside]], despite him getting symptoms similar to humans like morning sickness and being even moodier than he normally is. Justified because not only is Concrete's body alien, but the baby was a result of asexual reproduction (though said reproduction was triggered by human sexual thoughts), Concrete's body is still in many ways a mystery, and everyone thinks of Concrete as being male as he was once a man.
* {{Exaggerated|Trope}} in ''ComicBook/TheUmbrellaAcademy'', when 43 women who hadn't been pregnant to begin with suddenly all give birth all the same time with no warning, right in the middle of whatever it was they had been doing at the time.

[[folder: Fan Works]]

* ''Fanfic/TheSecondTry'': Due to her mess of insecurities, Asuka flipped out when she discovered she was pregnant and had tried to hide it from Shinji; she even stopped eating in a misguided attempt to induce a miscarriage. Shinji found out anyways; a rat got into their trash while he was taking it out and he found a positive pregnancy test Asuka tried to hide. To say he was surprised would have been an understatement.
** Incidentally, Asuka avoids the usual markings of trope as what tipped her off to her condition was missing one of her periods.
* In the backstory of Kyon's mother in ''Fanfic/KyonBigDamnHero'', it took a while for her to realize she was pregnant of Kyon due to a mix of ignorance and her lack of physical growth, compounded by a FriendlessBackground and a strained relationship with her parents.
* In the ''Franchise/SailorMoon'' story ''[[ Misconception]]'', the plot is kicked off when Usagi learns about Chibi-Usa's previously-unmentioned older brother. One whose birthday is roughly eight and a half months away...
** As with the above mentioned Second Try case, it was only Chibi-Usa's comment that revealed it to Usagi. The ensuing nausea was from the shock and stress of learning she was going to be a mother far earlier than she realized, not morning sickness.
* In the ''Film/StarTrek'' fanfic ''[[ Safe and Sound]]'' we find out early on that Uhura is pregnant with Spock's child. She and the senior officers find out when the computer scans her and informs everyone (the biggest reactions come from Kirk and Scotty, the former spitting his mouthful of water into [=McCoy's=] face and the latter falling off his chair). This one is justified in that she was only one month along (before she would have noticed the missed period and before morning sickness came into play) and she and Spock didn't take precautions because of [[MateOrDie a certain incident which happens to Vulcans every seven years]].
* In the ''Film/StarTrek'' fanfic ''[[ Kirk Starts A Family Aboard The Enterprise]]'', Kirk discovers while undergoing a routine physical in Sick Bay aboard the ''Enterprise'' that the reason for his apparent weight gain is that [[MisterSeahorse he's pregnant]]. Justified in that Kirk is a female-to-male transgender person. Kirk decides to [[PregnantBadass continue performing his duties while he's pregnant]].
* In chapter 62 of ''FalloutEquestriaProjectHorizons'', a medical scan during [[spoiler:a cybernetic upgrading]] reveals that [[spoiler:main protagonist Blackjack]] is pregnant. It comes as a particular surprise to her because she's still using a contraceptive implant. The medical ponies speculate that [[spoiler:Blackjack's {{Magitek}} cybernetics saw the implant for another piece of useable scrap material and absorbed it]].
* Done more realistically in ''FanFic/MegaManReawakened''. [[spoiler: Tron Bonne]] finds out after 2 months of pregnancy, and tells the other characters soon after.
* Used in ''EggBelly'', when Konoka gets pregnant by a girl. [[spoiler:Apparently, Pactio sex can give even same-sex couples a child.]] The scene where the doctor tells her this is hilarious.
* In ''Fanfic/ExtendedStay'', the Mistress and the Superjail crew find out she's pregnant just when Ultraprison is about to leave. This one is justified since she hasn't been far enough along to exhibit any symptoms.
* A minor character in ''Fanfic/RedFireRedPlanet'', Master Chief Special Warfare Operator Haellh, mentions to Admiral Riker early in chapter four that she's six weeks along. Her fellow fireteam member Petty Officer Freeman is really surprised by this and complains about her not telling him, but she says she only found out a few hours before.
* It's mentioned in ''Fanfic/KillLaKillAU'' that Ragyou's pregnancies with Satsuki and Ryuuko were these, as, in the case of the former, she didn't found out that she was carrying until she was showing and, in the case of the former, she wasn't prompted to find out that she was pregnant, until someone pointed her being pregnant with Ryuuko out as a possibility, however, the latter is a bit more explainable, as, considering that she had complications as she was giving birth to her oldest (the which almost killed her) and the resulting surgeries, it's possible that, even after she's completely healed, she didn't think she could get pregnant again, let alone carry another to term.
* Ran's pregnancy with her kits in ''[[Fanfic/Gensokyo20XX Gensokyo 20XXI]]'', however, probably due to being servile, she didn't know the symptoms and just assumed she was getting fat, until she pieced together why Chen and Flandre were quite eager to forego eating, so she could have their food.
* Minor example in the DistantFinale of ''Fanfic/BrotherOnBrotherDaughterOnMother''. Eleya mentions in her InternalMonologue that she only discovered she was pregnant with her and Gaara's fourth after he had left for a five-year mission. She's forty at this point, so they may not have thought she could get pregnant again.

[[folder: Film]]

* The Creator/MontyPython movie ''Film/MontyPythonsTheMeaningOfLife'', previous to the infamous "Every Sperm Is Sacred" song, featured a poor Yorkshire family whose mother was having babies drop right out from between her legs as she cooked and cleaned for her burgeoning family, with her only reaction being to say "Get that for me, would you, Deidre?" to one of her older children. This may also be implying that it's less that she didn't know and more that she didn't care, since they had dozens of children already.
* The new cute swimming instructor in ''WaterBoys'' discovers she's eight months pregnant and goes on a maternity leave immediately after managing to convince her five team members to throw away their pride and join her synchro-swimming team for her.
* Emmeline in ''TheBlueLagoon'' becomes pregnant with Richard's child and has no clue whatsoever until ''after'' she's given birth. She even tells Richard she doesn't ''know'' why she had a baby. Justified due to them having been living on the island since they were children and having no formal sex education whatsoever.
* It's unclear how long she knew about it, but ''[[Film/TheAddamsFamily Addams Family Values]]'' starts with Morticia announcing that she's going to have a baby...right now, and being rushed to the hospital for delivery. (The surprise is only within the context of this movie, though, as the SequelHook of the previous one had her wordlessly announcing said pregnancy by way of knitting baby-sized pajamas.)
* In ''Film/{{Father of the Bride| 1991}} II'', Nina winds up getting pregnant at roughly the same time as her recently-married daughter. She initially mistakes the symptoms for menopause. And she is at an age where menopause would be probable, so her surprise is rather more believable than most examples.


[[folder: Jokes]]
* There's a grammar joke that goes like this:
-->Sex. Sex. Sex. Sex (OhCrap)
** The joke being that the periods after each "sex" are ''menstrual'' periods.

[[folder: Literature]]

* In ''Literature/ABrothersPrice'' Mother Eldest first thinks it is menopause when she doesn't get her period anymore. She is delighted to find out it is SomeoneToRememberHimBy.
* In the satirical 'legend' of Pope Joan, a woman went to Catholic school disguised as a boy and worked her way through the ecclesiastic ranks to Cardinal and finally Pope. Her cover was blown when she put her foot in the stirrup to mount her horse and promptly gave birth before a shocked audience.
* In a subversion, Maya Angelou relates that she knew she was pregnant in ''IKnowWhyTheCagedBirdSings'', but the surprise was certainly on her family after she hid it from them for eight months.
* Implied in ''Discworld/TheFifthElephant''. Even if Lady Sybil wasn't surprised, [[CrowningMomentOfFunny her husband most assuredly was]], and his stupid questions and her dry responses are particularly [[HilarityEnsues hilarious.]]
* Daisy's mother in ''TheStoneDiaries'' is unaware that she's pregnant.
* Bluestar in ''[[Literature/WarriorCats Bluestar's Prophecy]]'', thanks to her one-night stand with Oakheart. She is unaware of her pregnancy until another cat points it out.
* A double-subversion from Literature/TheBible: Sarah has overheard three men (actually [[AngelUnaware angels in disguise]]) telling her husband that he and Sarah will have a son. She laughs because [[ButICantBePregnant she is old and has been infertile for a long time]], and gets [[WhatTheHellHero called out]] for laughing by the angels, which shuts her up. Sure enough, she does become pregnant, and she names her son Isaac (because she laughed at the prospect of having a child at her age, and boy was she wrong!)
* In ''Literature/KingdomOfLittleWounds'', Ava realized she was pregnant after Jacob had already left her. She insists that Jacob ejaculated on her stomach.
* In ''Literature/DancingOnTheEdge'', it's mentioned that protagonist Miracle's mother wasn't aware she was pregnant for several months since it barely showed until the later months, and since she, as a dancer, was already very thin and implied to be anorexic she wasn't tipped off by her missed periods.


[[folder: Live Action TV]]

* This happened to Peggy Olsen in ''Series/MadMen'', such that she didn't know until she ''went into labor''.
* Was a plot point on ''Series/EastEnders'' a while back where a teenager gave birth not having a clue.
* Happened to an obese woman in a first-season episode of ''Series/StElsewhere.''
* The aptly-titled ''I Didn't Know I Was Pregnant'' is about this. See the "Real Life" category for details.
* A fat woman complaining of severe cramps went into the ''Series/{{ER}}'' and not only realized that she was pregnant but that she was giving birth to twins. Dr. Benton had to deliver the baby--something he "hadn't done since med school."
** Elizabeth Corday gets hit with this in the seventh season. Her response to the news was a flat "That's impossible."
* ''Series/AllMyChildren'''s Opal Cortlandt learns she's pregnant after several weeks worth of what she assumed were menopause symptoms. Not to mention her husband's supposed infertility.
* ''Series/DoctorWho'' Series 6 gives one to Amy Pond. The surprise element is made more plausible, so to speak, by having the Amy we see be a (non-pregnant) duplicate with her consciousness, while her comatose (pregnant) real body is elsewhere.
* Happened in the latest series of ''Series/{{Whitechapel}}'' when DS Miles' wife fears she might have ovarian cancer only for it to turn out she's 6 months pregnant
* At the end of "Baby on Board", ''Series/ModernFamily'''s third-season finale, Gloria [[ConfessionCam tells us]] she had thought she was carsick but, no, she's really pregnant, as the camera shows her buying a pregnancy test kit.
* Appears in the ChristmasEpisode of ''Series/CallTheMidwife''.
* A minor point in the fifth season of ''Series/{{Castle}}''. [[spoiler:Ryan and his wife are having trouble getting pregnant... because they're already pregnant.]]
* During one of his much-loathed clinic visits, ''Series/{{House}}'' meets a woman who wants to know why she's been feeling sick and can't seem to lose weight. House later explains that she has a "parasite", which he can't legally remove after a month. She expresses disbelief since she's been using birth control.
-->'''Woman:''' And my doctor said I might not get any periods at all if it was working...
-->'''House:''' Interestingly enough, you also don't get any periods if it ''isn't'' working.

* Averted in Music/EricChurch's "Two Pink Lines". The young man and woman in the story notice that the woman is two weeks late, so she takes a pregnancy test and the two of them angst over it. [[spoiler:The test comes up negative, so she leaves at the end.]]

[[folder: Theatre]]

* In the stage play ''E/R'' (basis for the half-hour 1984 sitcom, not the hour-long 90's drama), a mother brings her teenage daughter into the hospital emergency room, complaining of "stomach cramps". The girl continues to deny she's pregnant even as she's giving birth.
* {{Played for Laughs}} in the stage musical of Roald Dahl's ''{{Theatre/Matilda}}'': Mrs. Wormwood is shocked to learn that she's pregnant, despite the fact that she (a) is nine months in, (b) is showing heavily, and (c) has been pregnant once before.

[[folder: Video Game]]
* In [[VideoGame/TheBookOfUnwrittenTales The Book of Unwritten Tales 2]], Ivo discovers that she's pregnant and is ''really'' surprised. In fact, discovering how the pregnancy came to be is her original quest in the game, even if she ends up getting involved in graver matters later on.

[[folder: Western Animation]]
* In ''WesternAnimation/FamilyGuy'', Peter looks up one of his old girlfriends; and is surprised to find that since he last saw her she's become very ugly and even fatter than he is. While they're talking, [[BlackComedy a baby plops out from between her legs]], surprising them both. She then yells to her offscreen husband, "You were right! I ''was'' pregnant!"

[[folder: Web Original]]
* On ''WebVideo/TheGuild'', Clara was well aware that she was pregnant. Her husband, on the other hand, was quite shocked to find out.

[[folder: Real Life]]

* According to [[TruthInTelevision The Learning Channel series]] ''I Didn't Know I Was Pregnant'', there are a number of reasons for why a woman might have a surprise pregnancy, regardless of whether she's ignorant of real life pregnancy symptoms or highly educated and self-aware. Examples include: infertility, improper contraceptive use, failure to realise contraception is not infallible, doctors not revealing antibiotics can damage contraceptive effectiveness, and spotting throughout pregnancy being interpreted as a normal period. There are several life-long health conditions that have many symptoms in common with pregnancy. Also, body shape, weight and the way a baby lies can disguise weight fluctuations or result in no visible baby bump.
* On either the same show or something similar, there was a story about a larger woman who had been thought to be infertile and thus didn't notice any of the regular signs of pregnancy. When she went into labor, she had been suffering from a bad case of constipation and thought she was trying to pass a bowel movement. The description she gives of what follows crosses the line from Nightmare Fuel into [[UpToEleven Nightmare Nitro]].
* Many British women's magazines have TruthInTelevision versions of this trope on a fairly regular basis. Multiple women have reported giving birth while on the toilet (one example was a teenage girl who had ovulated but not had a period before; another was a woman who, due to how the baby was positioned, didn't at all look as though she was pregnant), having to then cope with the shock of it and having to break the news to their loved ones.
* In 2012, there was news of a woman who did not know she was pregnant until she gave Afghanistan, in the middle of a war zone. ''After serving as a bombardier in battle''. So she qualifies for PregnantBadass, even if she hadn't been aware of it. Justified because the normal signs of pregancy (lack of periods, stomach pains, vomiting) can be chalked up to the stress of battle.
* In the late 1990s, a woman made the Seattle news after she went to the hospital with terrible stomach pains and delivered a healthy 6-pound baby girl. As her periods had always been light and irregular, and she continued to spot throughout the pregnancy and had no baby bump at all, she had no idea she was pregnant until she gave birth.