Law of Inverse Fertility



"''"Once on a time there was a king and a queen who had no children, and that gave the queen much grief; she scarce had one happy hour. She was always bewailing and bemoaning herself, and saying how dull and lonesome it was in the palace. 'If we had children there'd be life enough', she said."''"

- "Tatterhood"

The fertility of a couple is inversely proportional to their desire to have a child.

Couples who want to have children will have trouble not only conceiving, but adopting and using surrogates as well. Women who don't want to have children, however, will be faced with unwanted pregnancies even if they used several different forms of birth control. Particularly if the conception was forced upon them. Teenagers, of course, will get pregnant their first time, double points if they thought they couldn't. The reason for this, of course, is obvious: "woman becomes pregnant with longed-for child immediately" and "woman doesn't want to get pregnant and doesn't" don't make for very good stories. At least the woman with a baby she doesn't want can give it up to the woman who is desperate to conceive, but expect much angst along the way.

In many cases the stress of trying to have a baby will suppress fertility, and, once the couple decides to adopt or give up, the stress disappears, and: hooplah! they have a baby! Sometimes it's after they went through the hassle of adopting, as if Mother Nature felt humorous one day. Many people believe this to be Truth in Television, but in Real Life, while infertile couples do sometime conceive after adopting, they also sometimes conceive if they don't adopt -- and at the same rate.

Conversely, as soon as a woman begins to accept her pregnancy, her chances of a Convenient Miscarriage double. Or if she's simply having a pregnancy scare from a missed period, it'll turn out that she's not carrying after all, just as she starts warming up to the idea. This particular trick is common on shows where Status Quo Is God; whether the former or latter version is used depends on how much drama the writers wish to evoke.

This is very old, involuntary infertility being found in the opening of a number of Fairy Tales, before the birth of the main character, and just about required for the Wonder Child. Note that this law gets revoked during the Denouement for Babies Ever After. See also But We Used a Condom

Anime & Manga

 * The Dragon Ball franchise has an uneven history with this trope. Trunks was apparently the result of a one-night stand between Bulma and Vegeta. And given the amount of time Goku spends either dead, traveling through space, training in the wilderness, or bedridden with a killer virus between and during the Freeza and Android / Cell sagas, it's amazing that he and Chichi ever found time to conceive Goten.
 * Word of God is that Goten was conceived in the ten day span between the virus and Goku's second death. Though whether this was planned or not is never stated. It was probably just an off-screen Pre-Climax Climax.
 * Fullmetal Alchemist- Izumi and Sig tried desperately to have a child, and when Izumi finally became pregnant the child was stillborn. She was then convinced that she  Don't worry, she didn't.
 * From that, her "divine punishment" from the Truth was to lose her uterus along with a few other organs, effectively making her infertile there on out.
 * Berserk: Being career mercenaries,

Ballads
"Out then spak her father dear, And he spak meek and mild; "And ever alas, sweet Janet," he says, "I think thou gaes wi child.""
 * In the Child Ballad Tam Lin, Fair Janet becomes pregnant after her first meeting with Tam Lin. Which raises the spectre of an Arranged Marriage to ensure that the baby is born in wedlock, and has her resorting to some desperate measures to ensure the right father marries her.


 * Something similar happens in the Backstory of Gil Brenton.

Comicbooks

 * In the Salvation arc of Preacher (Comic Book), Toby and never-seen girlfriend Turleen aren't even thinking of having a baby (or much else, for that matter) when he tells Jodie that he thought she was pregnant because she'd missed her period. They're not worried, because it happened once before, last month. God, these two are such idiots.
 * In the Green Arrow miniseries The Longbow Hunters, Ollie tells Dinah he'd like to get married and have children. She says no, because their lives are too dangerous. A few years later she changes her mind...at which point they're informed that due to damage she sustained during Longbow Hunters, she's not physically capable of having kids anymore.
 * In Runaways, Victor learns that his mother wanted a child but was infertile and unable to adopt because of her past as a drug mule.
 * In Y: The Last Man, the (literal) last man on Earth manages to have sex exactly twice (in one night, with the same woman) in the years directly following the plague that killed all the other men. Nine months later, guess who's the last father on Earth?
 * Spider-Man's Aunt May had a miscarriage that left her infertile. She and Uncle Ben were more than happy to adopt Peter when his parents died, though it makes one wonder why they didn't try adoption before.
 * Ma and Pa Kent wanted a child, but weren't able to have one before baby Kal-El landed in their backyard. Some stories try to explain this, like Superman and Batman Generations which shows that.

Fairy Tales
"A long time ago there were a King and Queen who said every day, "Ah, if only we had a child!" but they never had one. But it happened that once when the Queen was bathing, a frog crept out of the water on to the land, and said to her, "Your wish shall be fulfilled; before a year has gone by, you shall have a daughter.""
 * "Sleeping Beauty", both Grimms' and Perrault's:


 * "Rapunzel"
 * In "Tatterhood", the queen is so eager to have a child, she neglects to follow the magical directions to get them.
 * "The Juniper Tree"
 * See also Wonder Child
 * "Momo-tarou" is the Japanese version of this fairy tale.

Film

 * Raising Arizona uses this as the crux of its plot, where a married couple can neither conceive (because the wife is infertile) nor adopt (because the husband has a shaky, criminal history), so instead they opt to kidnap one of the recently-born Arizona quintuplets, since the father was quoted in the media as saying they had more children than they could handle.
 * This particularly fits the trope because the wife is absolutely desperate to have a child. When she finds out she can't, she's so depressed she quits the police force.
 * Baby Mama.
 * The whole point of the movies Juno, Knocked Up, Waitress, Saved, and going back a bit further, Maybe Baby.
 * The Ring.
 * In Hannah and Her Sisters, Mickey is told he is infertile. He and his wife Hannah have twins via in-vitro fertilization and a sperm donation from a family friend. Years later,
 * The introduction to Idiocracy features a highly intelligent couple who want to have a baby but keep putting it off for various reasons (not ready; not settled; husband's infertile; husband's dead; husband's frozen sperm melted in an accident...) while dumb white trash Clevon having a continually growing family tree. Particularly funny when Clevon gets into a crotch-related accident, but still has a dozen more kids after that.
 * In Beetlejuice the one cloud in Adam and Barbara's blissed-out life is their inability to have a child - but by movie's end, they've become sort-of surrogate parents to Lydia.
 * Handled with wonderful subtlety in the film Julie and Julia. At one point near the beginning, Julia gives a woman passing by with a stroller a longing look; later in the film, she gets a letter informing her that her sister is pregnant, and while she tries to express joy she can't help bursting into tears instead. That's all we get on the matter.
 * In the second Look Who's Talking film, Mollie gets pregnant with Jimmy's daughter and Mikey's half-sister, Julie, despite wearing her diaphragm. The diaphragm is also a Chekhov's Gun from the first film.
 * Cthulhu (2007). The father of the protagonist wants his gay son to start a family; naturally he refuses and snidely suggests pressuring his sister instead. She immediately storms off crying as she's been unable to have children.
 * In Eat Drink Man Woman, gets pregnant after sleeping with her boyfriend once.
 * In Match Point, Villain Protagonist Chris Wilton has trouble conceiving with his wife, but knocks up his mistress pretty much immediately, the irony of which he notes ruefully.
 * In Diary of a Mad Black Woman, Helen wanted to have children with Charles, but had two miscarriages. Meanwhile, he had two unplanned children with his mistress.
 * As noted below in the Western Animation section, the trope was played very straight with The Flintstones, in the film as well as the cartoon. The difference is that in the film, the Rubbles decide to adopt, and Fred empties his savings account to lend them the money so they can afford to do so.
 * In the dark comedy Kingdom Come, Luanne's angst comes from her inability to have children. She had multiple miscarriages, her latest one lost in an empty fried chicken bucket (she was ordered on bed rest and was using it as a makeshift bedpan while her husband Ray went to the drug store to buy a real one; a KFC bucket becomes a Trigger for her). She and Ray stopped trying after that.
 * The Curious Case of Benjamin Button, Queenie wants a child but can't have one. The only child she raises is Benjamin, who loves her and later says that Queenie is born to be a mother.
 * Part of Bethany's backstory in Dogma is that she was married and she and her husband both wanted children very much. But then she had cancer and the cancer treatments left her infertile, so her husband left her.
 * Claudia desperately wants a child in Snow White a Tale of Terror, but she only carries to term/gets pregnant (the film doesn't specify which) the one time in nine years. The baby doesn't live.

Literature
"Now, family size; that was the real, secret, wicked fascination of Barrayar. There were no legal limits here, no certificates to be earned, no third-child variances to be scrimped for; no rules, in fact, at all. She'd seen a woman on the street with not three but four children in tow, and no one had even stared. Cordelia had upped her own imagined brood from two to three, and felt deliciously sinful, till she'd met a woman with ten. Four, maybe? Six?"
 * In Twilight, Rosalie and Esme can't ever have kids and yet they really, really want them. Bella, who wasn't trying to have kids and in fact wasn't even thinking about them, gets pregnant the very first time she and Edward have sex, despite being explicitly incapable of it. Justified if (as they imply) a vampire can't get pregnant but a vampire can get someone pregnant.
 * Averted entirely in Lois McMaster Bujold's novel Barrayar. Cordelia, who's actually trying to have a baby with her husband, gets pregnant first go, while her friend Drou, in the midst of a pregnancy scare after an ill-judged encounter, is not. And then the real plot starts.
 * But Cordelia had been looking forward to having several children. Growing up, Miles is uncomfortably aware that his parents had chosen not to, to protect their "mutie" son from being shunted aside.


 * Aunt Sissy in A Tree Grows in Brooklyn wants a child more than anything, but all her pregnancies result in stillbirth. She finally fakes a pregnancy and adopts the child of an unwed Italian girl, and about a year later becomes pregnant and has a healthy baby boy.
 * A Soldier of the Great War references this trope. A young boy is talking to the protagonist about various fertility superstitions he's heard about. Alessandro tells him that the real rule is "Once if you're not married; a thousand times if you are."
 * In Dan Abnett's Warhammer 40000 novel Brothers of the Snake Antoni explains to a Space Marine that she has had two husbands and no children -- presumably because of her Heroic Bystander actions earlier in the novel, when she went with him to where a Dark Eldar ship crashlanded, and was exposed to heavy radiation.
 * Federico García Lorca's Yerma is mainly about this topic: a woman who wants a child but can't get pregnant no matter what.
 * Happens to Detritus and Ruby as their relationship is developed through the Discworld series. Vimes noted that their marriage was happy but childless. They do however adopt Brick later in Thud.
 * Happens to two "friends" in I'm So Happy For You.
 * A major part of Gordie's character in "The Body" (the Stephen King novella that later became the film Stand by Me): his late brother Denny was born after a series of miscarriages and stillbirths and regarded as a gift from God, while he came along ten years later, when his parents didn't want another child.
 * Sonea in The Black Magician Trilogy falls under this trope from the virgin side of things. And manages to get pregnant while in the very stressful situation of  High stress isn't usually conducive to fertility.
 * In The Mists of Avalon, Gwenhwyfar desperately wants to bear Arthur's child, but instead has miscarriage after miscarriage . Morgaine, on the other hand, got pregnant with Gwydion (Mordred) the first time she ever had sex.
 * In the Codex Alera, Amara fears that she is infertile because she was 'blighted' (A potentially lethal disease that renders the majority of its female survivors infertile) in her youth. Bernard, her husband, points out that not every blighted woman is infertile, so they resolve to keep trying until they get the child they desperately want (Repeatedly, and with much enthusiasm). After years of (Very enjoyable) efforts, Amara finally resolves herself to never being a biological mother and instead focuses on caring for the orphaned children whose parents were killed in the recent fighting..
 * In Katherine Kerr's Deverry Cycle, the Maelwaedd clan has something of a succession crisis looming. Rhys is the ruler and needs an heir. He's been married for years and his wife hasn't given him any children at all. His brother Rhodry isn't so burdened, has a way with the ladies and accidentally gets a servant girl pregnant. Rhys, meanwhile, is forced by politics to cast off his wife for one who isn't barren and his cast-off wife is given to a widower with so many children, he needs a wife to mother them but doesn't need any more heirs. Within a year, Rhys's cast-off wife is pregnant and giving birth causing everyone realises the infertile one is actually Rhys (nobles start whiling away their time by placing bets as to whether his second wife will ever get pregnant). Rhys tries to solve this problem by adopting Rhodry's illegitimate child as his legal heir, but things don't go well for him.

Live-Action TV
"Vicki: Well, it's not like we've been doing anything else."
 * Brilliantly subverted in Frasier, when Niles and Daphne were trying to have a child. Niles finds out that he has lethargic sperm and goes through a whole rigmarole of ridiculous procedures to increase chances of impregnating Daphne. He then finds out that she is already pregnant. Played straight, however, with Roz, who gets pregnant even though she doesn't want to and has been using birth control.
 * Similarly subverted in Mama's Family, where Vinton and Naomi had reached the end of their rope (turned down for adoption, Vinton's low sperm count) and were about to move away from Thelma's house after a nasty row, only to find out Naomi was pregnant after all.
 * Happened both ways in Friends. Rachel at one point ended up with a crisis pregnancy, although despite rumors, Jennifer Aniston wasn't pregnant. The storyline was written to add tension to the whole "will Ross and Rachel get back together?" thing. (However, Lisa Kudrow really did get pregnant, causing the writers to scramble for the ridiculous "having her brother's baby" plotline.) Towards the end of the series, Chandler and Monica spent several episodes trying to have a baby, but it eventually turned out they were both nearly infertile, making them effectively sterile as a couple. They ended up adopting. Ironically, Courtney Cox was actually pregnant when the adoption episodes were filmed.
 * On Desperate Housewives, Gabrielle took a tumble down the stairs a few minutes after she accepted her pregnancy. When she later decided she wanted to try to have a baby, "complications" from the fall made her unable to do it the old-fashioned way. She and Carlos attempted to adopt a baby but were thwarted when an employee of the agency blabbed Gabrielle's history of statutory rape and Carlos' slave labor charges. They managed to adopt a child through the services of a private adoption lawyer but the biological mother had a change of heart and took the child back. Finally, they used a surrogate, and nine months later discovered there had been an embryo mix-up and the baby belonged to someone else.
 * In Season 5 we find out Gabby had two miracle pregnancies...right after her husband went blind and they lost all their money.
 * Lynette gets pregnant at the end of Season 5, despite having just undergone a chemo and being, judging by the age of her older children, well in her forties. Well, at least it gave occasion to one of the best lines of the season "Are you sure it's not cancer?"
 * On One Tree Hill, Brooke Davis wants to be a mother, but her foster daughter leaves her, and she ultimately discovers she is infertile.
 * In That '70s Show this trope is invoked when Eric and Donna realize that Donna had missed a day of her birth control, and were therefore convinced that Donna was pregnant. Most teenagers don't realize that birth control doesn't stop working just because you missed one day, so their panic is understandable.
 * On 3rd Rock from the Sun, Vicki and Harry go to a doctor when they can't seem to have a baby. Subverted in that they had only been trying for a month.


 * In an episode of Dharma and Greg, Dharma became convinced that she and Greg were about to have a baby after seeing a vision. They tried to have a baby for a long time, using various methods, but, in the end, it was Dharma's middle-aged mother who became pregnant. Dharma explained that her vision was correct, but that she just misplaced its womb.
 * In Sex and the City, Charlotte, who is the character who's the most excited about the idea of marriage and family, turns out to have trouble conceiving. Miranda, who's more lukewarm on the subject, suffers an unplanned pregnancy. What's more, Miranda had a lazy ovary and the man who impregnated her had lost one testicle to cancer!
 * Charlotte does get pregnant in The Movie, though, as an example of "getting pregnant once you stop trying."
 * Also averted with Samantha, who remains adamant that she doesn't want children throughout the series and movie, yet never even has a scare.
 * Actually she mentions that she has had two abortions.
 * Carrie and Doug's difficulties in having a baby were used occasionally on The King of Queens. One two-part episode had Carrie get pregnant, only to suffer a miscarriage. In the Grand Finale they end up adopting, only to find out that they are having one of their own as well.
 * Mad Men uses this both ways with the same character:
 * Again played two ways with, who tries for months to get pregnant with her husband's child, worrying that past abortions have possibly made her infertile, then becomes pregnant with   on their one-night stand (and her only episode of infidelity).
 * Betty discovers she's pregnant while estranged from Don and considers aborting. They reconcile, but not much later they split up for good, and she's holding the baby on the plane as she and her second-husband-to-be fly to Reno to obtain the divorce.
 * Through flashbacks, we find out that Son of a Whore Don was only taken in by his father's wife because all of her pregnancies had ended in stillbirths and she desperately wanted a child. She had a son of her own about ten years later.
 * Provides the motivation for murder in the Cold Case episode "Family".
 * This appears to be law #1 on Lost's island. Pregnancy is a death sentence for mother and baby, but normal sperm count is magnified by five.
 * Also seen in flashbacks. Sun and Jin desperately want a baby, and can't conceive. Claire is on the pill, and gets pregnant.
 * Coupling: in the season finale Susan is desperate to conceive but is told the chances are low, while Sally has a pregnancy scare when she doesn't want a baby - subverted as Susan finds out at the last minute that she's pregnant, and Sally isn't (Jane was also involved in the test mixup and she was not pregnant).
 * An episode of The Last Detective had the culprit specifically call attention to this trope in her Motive Rant.
 * Cuddy from House went to great lengths to get pregnant. When that doesn't work out, she tries to adopt which doesn't work out either, at least at first.
 * Played hilariously straight on Scrubs, where J.D. accidentally impregnated his girlfriend without even having sex with her (he didn't have a condom, and he didn't want to get her pregnant), Jordan and Dr. Cox had Jack with their relationship being little more than a booty call, and Jennifer Dylan after Dr. Cox had three vasectomies. Turk and Carla, on the other hand, had to both have fertility tests and counseling before they finally had Izzy.
 * Played straight in the last season with Carla and Turk too. Carla gets pregnant a second time when they weren't really trying. No one cared other than the couple though.
 * Notably averted in How I Met Your Mother. In Season 4, Marshall and Lily decide that the time just isn't right for the two of them to have a baby, and they actually make it stick; Lily doesn't get pregnant. What makes it notable is that Alyson Hannigan, the actress who plays Lily, was pregnant throughout season, but the writers still passed on the chance to write it into the story.
 * In an unbelievable coincidence, Cobie Smulders (who plays Robin) was also pregnant at the same time, and her character also had no desire for kids. Which makes this a Double Aversion and a Crowning Moment of Awesome for the writers who actually pulled it off.
 * Played straight in season six, where Lily and Marshall have decided that they want a baby and are having trouble conceiving.
 * Subverted as of "Bad News." Marshall and Lily both learn that they are fertile. They've just had bad luck so far.
 * Brutally subverted in season 7 when Robin, who absolutely despises kids, gets a pregnancy scare only to find out that not only is it a false positive, she's infertile. She has no idea how to react to it, because she's never wanted kids, ever, but the knowledge that she can't have them, period, makes her realize that she might've wanted them someday, but now that choice has been taken from her and she'll never, ever be able to change her mind. It's made even worse when she's trying to convince herself that infertility is a good thing, now she'll never have to worry, she has no right to be sad because she never wanted kids in the first place, she's glad her and Barney's beautiful future kids that she's been imagining telling the story of how she met their father to aren't real...
 * South of Nowhere has Chelsea getting pregnant to Clay, and then deciding that she can't go through with an abortion. She later loses the baby in a car accident.
 * Played with in Hex: Cassie falls pregnant to Azazeal while under his influence. Upon discovering that she's pregnant, she decides to abort it.
 * Used multiple times in Six Feet Under. Spoilers ahoy:
 * Glee features Terri, who is desperate for a baby yet can't get pregnant. Meanwhile the religious celibacy club president Quinn cheats on her boyfriend and has sex with his best friend once and ends up pregnant. The two stories then overlap as not only do both women pull The Baby Trap on their respective men but Terri is attempting to secretly adopt from Quinn.
 * On the other end of the scale it is a miracle that Brittany hasn't become pregnant. She has claimed to have had sex with almost every guy in the school and yet she thinks using protection means having a burglar alarm and additionally she still thinks babies come from the stork.
 * There's also Shelby Corcoran, who after  is told she can no longer have children.
 * On The West Wing, we find out via flashbacks that Toby's wife Andi desperately wanted to have a baby, and they tried every fertility treatment under the sun. In the series timeline, they're divorced, but Andi becomes pregnant with Toby's twins -- and then rejects his proposal of remarriage, saying that he's "sad," "angry" and "not warm," and she's worried about the influence he would have on the kids. Oddly, we're never told whether she finally had a successful in vitro fertilization using his stowed-away sperm or they rekindled their relationship long enough to do it the old-fashioned way. This is a point of contention is the fanbase: one side insists that it's too much of a long shot for Andi to have become pregnant just by luck, after failing for all those years, while the other maintains that if those are really her conclusions about Toby's potential as a family man, she wouldn't have intentionally made him the father of her children.
 * On The X-Files, Scully is not only told she is infertile, but that she had her ova removed. While she had never given that much thought to having children before, she did after hearing that. An invitro attempt with Mulder failed, as did trying to adopt, and yet by the end of season seven Scully is pregnant by circumstances never fully explained. However, Word of God did confirm that Mulder is the father of Baby William.
 * In an episode of Legend of the Seeker, Kahlan gets magically split into two people, each one representing a major part of her personality: a highly-emotional Kahlan with no powers, and a cold, calculating Confessor who enforces draconian laws whether or not they are moral. Both of them end up having sex. The emotional Kahlan finally sleeps with Richard, and the Confessor Kahlan sleeps with a tyrant she has confessed purely for procreation. When it comes time to re-join them, both claim they could be pregnant from a single encounter. Zedd, however, performs a magical scan and determines they aren't pregnant. He claims this is because they are not real people.
 * Happens on Martin. His girlfriend Gina misses her period and Hilarity Ensues as they and their friends scramble about getting her tested for pregnancy and if they're ready for a baby. Just when Martin and Gina warm up to the idea of having a child, it turns out she wasn't pregnant after all.
 * On Spartacus: Blood and Sand and Spartacus: Gods of the Arena, Lucretia tries for years to provide her husband Batiatus with an heir, even resorting to adultery with one of his gladiators due to the belief that a Gaul's seed was extraordinarily potent. Despite regularly having sex with both men and undergoing a fertility ritual, she remains unable to conceive.
 * Flagrantly abused by Shonda Rimes on Greys Anatomy. To date:
 * Addison cheats on her husband with Sloan, gets pregnant, aborts, and then when she tries to have a baby on her own finds out she's barren
 * Cristina gets pregnant on accident, turns out to be ectopic and miscarries
 * Bailey, who after 7 years of trying, gets pregnant right when she's about to become an attending
 * Adele gets pregnant at age 50 while seperated from her husband, only to miscarry once they've reconciled
 * Callie and George briefly talk about trying to have a baby which doesn't happen
 * Sloan knocked up some chick when he was young and dumb and his daughter shows up in season six, ALSO knocked up (also young and very, very dumb)
 * Meredith gets pregnant, and though she is happy about it she WAS on birth control... but then miscarries. She then spends all of season 7 trying to get pregnant only for...!
 * Sloan to knock up CALLIE, who up until about five minutes prior was in a committed relationship with another woman.
 * Implied to have been the case with Jessica and her late husband Frank on Murder, She Wrote. In the pilot, Jessica explains her childlessness to a new suitor by saying "We were never blessed in that way."
 * This is really played up in the Korean Drama Ojakgyo Brothers. Cha Soo Young had surgery that removed one ovary completely and partially removed the other, yet became pregnant by a one-night-stand with her coworker.
 * Both sides are featured in Boardwalk Empire. On the one hand, Rose Van Alden, who wants a child more than anything in the world and practically considers sex a chore to get that, can't conceive. Her husband Nelson is not so thrilled about having children himself  Meanwhile, Lucy had suggested to stop using birth control in order to secure Nucky for herself, but only gets pregnant after he has abandoned her.
 * Avoided, mostly, on Star Trek: Deep Space Nine. Keiko opens up one episode by telling her husband, Chief O'Brien, that she's pregnant. While there was no build-up in previous episodes of them wanting a second child, they apparently were trying. O'Brien is simply disappointed because he wanted to have to keep trying a little while longer.
 * In season five of Stromberg, Jennifer gets pregnant with Stromberg's child, which was unwanted and thought they had used birth control. Conversely, in the same season, Tanja and Ulf are trying to have a child, but it turns out that Ulf is infertile.
 * On Charmed, after a year of marriage, Piper and Leo admit that they've been trying to have a baby for a while but have been unsuccessful. Piper eventually finds out that all the demon-hunting and "sharp blows to the abdomen" have made it "difficult if not impossible" for her to get pregnant. Meanwhile her sister Phoebe, who has been married for a month to the Source of All Evil but doesn't want children does get pregnant. She at first doesn't tell Piper about her pregnancy because she knows it will hurt her; when Piper does find out she says this is ridiculous and that she would love to be an aunt if she can't be a mother. Subverted in the end when Phoebe's fetus is taken from her ( It Makes Sense in Context )and Piper finds out she has gotten pregnant.

Music

 * Played with in The Decemberists' The Hazards Of Love concept album. The Rake, who really doesn't want kids, got four. Subverted with the Star-Crossed Lovers William and Margaret, who, also in accordance with the trope, seem to conceive very quickly. Although it's kind of a problem, they're extremely happy about it.

Religion & Mythology

 * Theseus's father visited an oracle to find out why he was childless. Theseus was conceived on the way home.
 * Genesis is ripe with examples of this trope; in fact, the only matriarchs who don't have problems conceiving are Eve and Leah (who in fact subverts this trope, having at least seven children). Sarah, Rebekah, and Rachel were all infertile, and all three required divine intervention in order to have children.
 * Not just Genesis; the respective mothers of Samuel, Sampson, John the Baptist. In fact, Michal, the wife of King David and daughter of King Saul, was the only notably infertile woman in the Bible who didn't eventually give birth (her infertility being a divine punishment). Mary, the mother of Jesus, could fall under this trope as well.
 * Apocryphal stories say that Mary's mother was also infertile for a number of years before having Mary at a relatively old age.

Tabletop Games

 * Weird variant in the history of Forgotten Realms monarch Azoun of Cormyr: A red wizardess of Thay once used magic to seduce the king, apparently believing that their son could one day make a claim for the throne, stealing it from Azoun's legitimate daughters. Subverted in that, while she may well have succeeded in one try, Azoun had already sired so many illegitimate children in his bachelor-prince days that hers would have to get in line behind hundreds of older half-sibs. She may have gotten the son she wanted, but he won't be any use as a political pawn.
 * In Werewolf: The Apocalypse and Werewolf: The Forsaken, if two werewolves engage in the forbidden act with one another despite the massive social taboos involved and punishment that will fall upon their heads if they are caught, then conception is a virtual certainty. Thanks to their dual physical/spiritual nature, this frequently applies even if they used protection. The resulting offspring are (in Apocalypse) sterile, deformed and frequently insane freaks or (in Forsaken) horrifyingly hideous vengeful spirits.

Theatre

 * Blood Brothers is a major example of this trope- Mrs. Johnston seems to have produced about ten kids and gives one away because she can't afford any more.
 * The Baker and his wife in Into the Woods want a child, but are magically cursed with infertility. Act 1 revolves around the quest they must complete before the Witch will lift the curse. (They have a baby in Act 2.)

Videogames

 * Played with in Baldur's Gate in the form of Aerie, and more straightforwardly, the mod-added Mary Sues Kelsey and Saerileth.
 * In the sound novel Umineko no Naku Koro ni, it takes Natsuhi and Krauss Ushiromiya 8 years after their marriage to conceive their daughter, Jessica. Krauss' ambitious younger sister Eva, however, gives birth almost immediately after she and Hideyoshi marry, so she tries to use this as a bargaining chip to secure her son George's headship in the family over Jessica.

Webcomics

 * Used in Arthur, King of Time and Space here. What kicks it up a notch is that it's the exact same people, but in different situations - one where they want to have a child, one where they don't. That particular comic makes it seem as though the desire to have a child is the one factor that keeps them from having one. Later averted in the space arc.
 * Eugene and Sara Greenhilt's contraceptive spell fails in Order of the Stick, leading to the protagonist's unplanned birth and the end of his mother's freewheeling lifestyle (until she got to the afterlife, anyway!)
 * Fur Will Fly ended with Tammy and Stewart trying (without much success) to have a kid while Brad and Page end up in a Shotgun Wedding.

Web Original

 * Frequently happens in The Gungan Council. Beth gets knocked up after her first time ever and Kirk, who vehemently does not want children, knocks someone up as well with just one encounter.
 * Quite a few surprise pregnancies occur in Chakona Space, most notably Admiral Boyce's first three children (all by different mothers of supposedly incompatible species). On the other hand most characters who want kids usually have little trouble making them, the major exception being Forestwalker's foxmorph mates Katrina and Kristopher.

Western Animation

 * The Simpsons - Apu and Manjula are trying to have a child with no success. Apu asks Homer how he and Marge did it, and Homer laughingly notes that each of their kids was unintentional. He then tries to deliberately invoke this trope to help them -- staging an entire setup where they were having sex dressed in teenage-y clothes in the backseat of a car, while Majula reads her lines in a monotone: "Oh no, I hope I don't get pregnant."
 * And of course, because apparently every member of the Simpson family sans Maggie was slipping Manjula fertility drugs, they have octuplets.
 * Also happened in Family Guy, where Lois and Peter tried to have a fourth baby. Of course they had Stewie actively working against them, and eventually shrinking down to destroy every sperm in Peter's body. Manually.
 * Delicately handled in The Flintstones, where it is implied that Barney and Betty Rubble are unable to conceive a child. After the birth of their goddaughter Pebbles, the Rubbles come by to see the new baby every night until one day Fred thoughtlessly orders them out of the house, which drives Betty to tears. Fortunately, their prayers are answered when the next day presents them with a Door Step Baby, Bamm-Bamm.
 * A flashback episode of King of the Hill reveals that prior to conceiving Bobby, Hank had been declared infertile due to a narrow urethra, which was exacerbated by his habitual uptightness. He and Peggy gave up on trying to have a baby and got a puppy (Ladybird) instead. Playing with the puppy was relaxing enough to counteract Hank's anatomical difficulties, and pregnancy ensued.
 * Later, when Hank and Peggy are trying to have a second child, Hank's seventy-something father Cotton winds up having a child with his forty-something wife Didi. After the baby is born and both parents are neglecting him, Peggy even miserably alludes to the fact that she can't have a child while they somehow got to have a "beautiful child they don't even want." Becomes a Crowning Moment of Heartwarming when.
 * Up. Subtly implied in the opening montage of Up. It's especially heartbreaking since the buildup has Carl and Ellie making a room for the baby. Word of God says it was a miscarriage that left Ellie unable to have more children. What we see is what little they could actually show/feel comfortable putting in a kid's movie.
 * In Disney's Hercules, the title character's adoptive human parents have prayed to the gods for years to bless them with a child, and they see Herc as the answer to that prayer.
 * In the ThunderCats (2011) episode "Native Son" a Flash Back reveals that the king and queen of Thundera tried to have a child for years. It got so bad that the queen worried she might be infertile. Their concerns were put to rest when baby Tygra literally flew into their lives in a balloon. So of course just when the royal couple have gotten comfortable with Tygra inheriting the throne as crown prince, the queen became pregnant.

Real Life

 * A book by Mary Pride points out that some people (like the author) may get so used to "family planning"-style matter-of-course birth control that they believe that merely going off the birth control is enough to cause pregnancy in a very short period of time. This is, of course, at odds with (statistical) reality -- even perfectly healthy, fertile couples can go months or in extreme cases years without a viable pregnancy while not using birth control.
 * If you have gone for years with your birth control method working perfectly, it can mean that eventually you become less vigilant about using it, or worry less about whether you might be pregnant even if you do have a condom break or forget to take a pill. But yes, women in their thirties or forties can still get pregnant by accident, and just because you never have got pregnant doesn't mean you can't.
 * After one year of "trying" (well-timed, unprotected sex) with no pregnancy, you meet the medical definition of "infertile." Most couples without a diagnosable medical problem will be pregnant by that point, although there are always exceptions...
 * Some infertile couples who take fertility meds to increase their chances of having just one child end up having... quintuplets. Or sextuplets. Or even more. (Due to multiple ovulation.) And once this fact is realized, the reality of low birth-weight and the chance of miscarriage sets in... and then some doctors may propose "selective reduction" to increase the chances of a normal birth-weight / normal term for the remaining babies.
 * See Jon and Kate Plus Eight. Or don't - you can find out more about them than you ever wanted to know just by reading the magazine covers while waiting in the supermarket checkout line.
 * Henry VIII. Except it wasn't so much "fertility" as "Law of Surviving Male Heirs". He'd have a child but it would be a girl, or it would then die or it would be a boy, live but, whoops, he was having sex with a mistress and the child was a bastard. Lack of an heir was a problem for kings for as long as there have been hereditary monarchies, but the Tudor succession has a positively geological impact on the history of Europe.
 * More the pity for his first wife, Catherine of Aragon, who gave birth to ten legitimate children... only two of whom survived long enough to even be baptized. The first was Henry, known as "Little Prince Hal, the New Year's Boy" (because he was born on New Year's Day), but he died a few months later. To make it even worse, the probable cause of Baby Henry's death (or at least a big contributing factor) was purging by his doctors. The other eventually became Queen Mary I, who had her own fertility heartbreaks. Running a government based on the fertility of its leaders doesn't work very well.
 * To give a somewhat more modern example also from the British Royal Family, the house of Hanover. King George III and Queen Charlotte had several children, but their sons, not so much. George IV had just one daughter, Charlotte, who was his heir apparent until her death as a young adult; after that happened, George's younger brothers (who were almost all single) sort of scrambled to marry and have children because there was the danger of a Succession Crisis. George outlived the second son, Prince Frederick, so he was succeeded by third son William IV. William had about a dozen children - but they were all illegitimately conceived with his mistress, an actress known as Mrs. Jordan; his legitimate children with his wife Adelaide all died within days of birth. Thus, when William died, the crown went to the only child of the fourth son, the Duke of Kent; you know her as Queen Victoria.
 * If a woman is actively pursuing a baby, there's a very good chance they're also dealing with a good amount of stress (if not the specific ticking biological clock, possibly a more generic "why isn't this working" frustration.) Stress can have some bad effects on anybody, and there are a few studies that suggest stress can affect infertility, creating a vicious cycle of "the more you obsess over a baby, the more likely you're not gonna have one."


 * Women face declining fertility as they age, so by the time some women are mature enough to have a child, they often can't have one due to infertility. So if older age = greater desire to have a child, and older age = less fertile, then it makes sense that the desire to have a child would correlate inversely with the ability to have one.
 * There are probably many men and women who don't want to have babies who are infertile, they just don't know it. Only when someone tries to have a baby (and therefore wants children) does fertility become an issue.