Mandatory Motherhood

We have a character who, while fertile, very much does not want children. But society, or the law, or destiny, will not let her get away with that easily.

Maybe there's a problem in the Heir Club for Men and she doesn't want to be involved but, since she's married to the fella needing the heir, she can't readily escape it. Or she's in a society that's gone through a class-2 apocalypse, which is urging every fertile woman to repopulate the species; but she has desires or concerns more important to her than the species.

Maybe she's been prophesied to be the mother of the Chosen One or The Messiah, but she wants to Screw Destiny anyway. Or she's prophesied to be the mother of The End of the World as We Know It and is desperate to Screw Destiny.

Or maybe she's already pregnant with the kid she adamantly doesn't want but has had abortion forbidden her for legal, moral or health reasons.

Whatever. She would rather not have children, but the law or the universe is doing its best to stop her, demanding she have children or else. (There must be a serious "or else" involved.) The law and the universe generally win these fights, but it still can be interesting to watch it go down.

Also, despite the name, this trope is not limited to female characters.

Contrast Convenient Miscarriage, which is, of course, on the opposite end of the Law of Inverse Fertility.

Anime and Manga

 * The Yuki-onna of Rosario + Vampire are required to marry at seventeen and start producing children immediately, due to the fact that the average Yuki-onna hits menopause before hitting thirty, leaving very little time for them to produce the next generation of a race that can't afford to have anyone not contribute to the long-term survival of the species. Mizore doesn't want to participate... at least, not with the guy her family picked for her (She makes it QUITE clear that she is willing to go through with this tradition using Tsukune instead).

Comic Books

 * In Elf Quest, nature decides when two elves are ready to have a child, and the elves aren't allowed to protest. This turns into a Mate or Die situation for several elves, most prominently Dewshine, who hates the mate that was chosen for her by destiny. But since Babies Make Everything Better, she loves her child regardless.
 * This trope actually gets twisted -- nature seems to consider genetics and population when deciding which two elves are to reproduce. The Skyriders, for example, have an inversion forced upon them: none of them had been able to conceive in centuries, despite very much wanting to have children among them. The Go-Backs, on the other hand, have an amazingly short lifespan because of their warring with trolls and living in harsh conditions and breed like any other mammals; when the Wolfriders mention Recognition, Kahvi is surprised that they still bother with that. As with most things, the Wolfriders have the ideal balance, as they reproduce often enough to maintain a cycle of life and death, but still have Recognition and only breed genetically superior children. (Except for Pike).

Fan Fiction

 * This is ubiquitous in Shipping fic. The happy couple will have kids, even if neither of them would ever want them in their canon personality and even if neither of them has a womb. There's no such thing as contraception, and miscarriages only happen when Deus Angst Machina decrees it. And if abortion exists, we're generally treated to a tedious speech about how Good Girls Avoid Abortion -- sometimes right away, sometimes after a few equally tedious scenes where they pretend to consider it. If the character isn't a "good girl" to begin with, she generally becomes one in short order thanks to Deliver Us From Evil.
 * A Fandom Specific Plot for Harry Potter is the "Marriage Law fic," where the Ministry passes a law saying that every available Pureblood and Muggle-born have to get married and produce a child within x number of years. Generally used just to force Hermione with whichever Pureblood that you prefer (though for some reason her official Love Interest Ron is never chosen.)
 * The Ikaris has an implied example. Due to three billion people dying in Second Impact, numerous countries implemented laws to loosen marriage conditions and discourage divorce to encourage family development and birthrates. Japan apparently never bothered to repeal them, due to being too busy trusting shadowy agencies to build giant robots to fight off alien monsters. Asuka angrily dubs Japan "the Las Vegas of Asia".

Literature

 * Nineteen Eighty-Four. Made hard for the protagonist as you must not derive pleasure from it and the women are literally trained to lie back and think of the party. Artificial insemination (or artsem in Newspeak) is recommended.
 * Camilla in Darkover Landfall: After being stuck on a Lost Colony, she gets pregnant thanks to Applied Phlebotinum and can't talk the doctor into giving her an abortion. She goes on to have a brood of children, and she doesn't seem to be happy about it. This ends up being a policy for all Darkovan women (particularly the Comyn). Later, Rohana Ardais also admits that she never wanted children, but had to have them.
 * Zig Zagged in S.L. Viehl's Blade Dancer: Jory and must Mate or Die; he wants kids, she doesn't. Jory is.
 * Kris in the Freedom series by Anne McCaffrey. Another Lost Colony situation in which everyone has to breed. But Kris is involved in an Interspecies Romance and is apathetic on having kids (and definitely against cheating), even if her alien boyfriend doesn't mind. Solution: uncharacteristic drinking to the point of blacking out and having sex with other humans. Twice.
 * To be fair, she didn't intend to sleep with him the first time- she'd broken her arm and was using alcohol as a painkiller since it was all they had. Unfortunately, it was stronger than she'd thought.
 * In the Liaden Universe books by Sharon Lee and Steve Miller, everyone is required to have one temporary Arranged Marriage and produce a child to be their heir, to whom he or she is a legal single parent. They can foster the kid to be raised by someone else, but Everyone. Must. Have. One. (The Liadens nearly went extinct due to a Planet Eater species.)
 * Roger and Cecilia Checkerfield from The Company Novels didn't want kids, and Roger got a vasectomy. Too bad that Roger was employed by Dr. Zeus, who forced him to adopt one of their scientific projects as his own son.
 * In Patricia A. McKillip's The Bell At Sealey Head, Ysabo is told the reason she must submit to the Arranged Marriage is to have a child; her mother and grandmother are baffled by her resistance, since she must have one.
 * In Diane Duane's The Tale of Five series, the entire human race is bisexual and both gay and poly marriages are common, but the Goddess requires that everyone must have at least one child at some point before they marry.
 * Lucia and Ben of Devil's Due would have liked to have officially started dating and having sex on their own recognizance and then decided for themselves, rather than having her be kidnapped while she's passed out due to anthrax poisoning and scientifically raped/artificially inseminated with Ben's sperm by the Cross Society.
 * In Margaret Atwood's The Handmaid's Tale, the Republic of Gilead has an entire caste of women (the Handmaids) whose sole function is to breed. Abortion and birth control for any woman are outlawed and punishable by the death penalty.
 * Subverted in Ursula Vernon's Black Dogs, where a character is raped for the sake of producing a powerful heir, but she aborts the zygote and to ensure that it never happens again she sterilizes herself.
 * The Iron Star has a thief who does not want to be a housewife or a mother or any kind of family woman. A Goddess overrules her (but the husband the goddess chose for her agrees to make life luxurious for her).
 * The Doctor Who novel The Eyeless takes place on a world where 99% of the population has been wiped out. The couple of hundred remaining survivors have worked out a plan for how many children each women must have in order for the species to survive long term -- and the loss of just a few children or potential parents could be devastating. The repopulation attempt is presented as an unfair, but necessary process, as it really is the only way their race is going to stay alive. At least one of the main characters, Alsa, is understandably upset about it, and her unwillingness to be a birthing machine for the rest of her life shows.
 * What happens if you refuse? Some extremely Unfortunate Implications, there.
 * The society is portrayed as level headed and moral, as well as pragmatic so it's probably meant to be an unrealistic idea that the issue would be forced. However in reality, who knows what could happen in such a situation.
 * The Warrior Cats don't often touch on this but in Bluestar's Prophecy, the title character is good with kits and raises her nephew after her sister's death but has no interest in having any of her own, . Naturally one of the Clan elders tells her she needs to "live her own life" now that her sister's son is grown. Because in order to live your own life, you have to have and raise children.
 * Lois McMaster Bujold's Vorkosigan Saga has a particularly odd one. While there was always an element of Mandatory Motherhood for Vor women, it was nevertheless understood and frequently referenced that many women might not want to have children, if only because, given the levels of technology available, it was a life-threatening risk every time. With the introduction of the uterine replicator into Barrayaran society, however, the concept of a woman who doesn't want children is erased, because the culturally acceptable 'excuse' for it is no longer valid.
 * Barrayar is still somewhat underpopulated even during Miles's young adulthood, and as his mother points out, traditionally the planet has had to struggle to maintain, let alone increase, its population. Plus the Vor are aristocracy, so it literally is mandatory for both men and women to have children if they want their line to continue. It's pretty much ingrained in the entire planet's society.
 * True, but prior to the introduction of the uterine replicator a cultural space existed in which it was possible for a woman to acknowledge not wanting children, if only for the reason of pregnancy being dangerous to life and health -- even if she couldn't get out of actually having them. With the introduction of a technology intended to improve women's health and reproductive freedom, that space was erased, making Mandatory Motherhood even more present -- and insidiously so -- in Barrayaran culture.
 * On the other hand, the uterine replicator itself is an instrument of sexual empowerment. It's noted that the Traditionalist political party won't be able to shove the new Empress into a maternity ward; she can breed and heir and still be a dominant force in the politics of the empire. Lady Vorkosigan herself has a fierce devotion to the galactic reproductive technology itself as a delayed action social time bomb; a few decades of gender selection of offspring results in an acute shortage of eligible brides, and the girls and their families are able to pick and choose from the bachelors available. A man expecting the traditional child gestation that left Miles himself teratogenically crippled finds it night impossible to get hitched. It should also be pointed out that Cordelia Vorkosigan was born and raised on Beta Colony, where children are precious commodities requiring a license for even a single offspring; Cordelia's displays of genetic greed have less to do with Barrayar than with Beta Colony.
 * Alluded to in Terry Pratchett's Nation. It's not clear exactly how old Daphne is, but her own culture certainly considers her a child; the people of the Nation, however, have pretty much a response of 'what do you mean you've not had a kid yet?'
 * In Bumped by Megan McCafferty, teenage girls are paid lots of money to be "surrogates" after a virus makes everyone over 18 infertile. They are not allowed to keep their baby and even take medication so they will not form any attachments to the baby. Motherhood is glorified and even schools are encouraged to have as much pregnant teens as possible.
 * Princess Varencienne is married to Valraven to provide him with an heir in Chronicles of Magravandias. She pretty much hates being a mother and refuses to have more children unless their son dies.
 * Arpazia in White as Snow bears a child after the king rapes her. Being his legal wife, she is expected to have more children, boys in particular. She, perhaps understandably, ignores her daughter completely.

Live Action TV

 * On Lost, Claire Littleton, left pregnant after her boyfriend walks out on her, plans to give the baby up for adoption, but a fortune teller advises her to take flight 815, which ends up stranding her on the island, where there are no adoption agencies.
 * In the new version of Battlestar: Galactica, a civilian approaches Doc Cottle looking for an abortion, since she's pregnant out of wedlock and her home colony (Gemenon?) has taboos against it. But since the entire human race is now small enough to fit in a football stadium, President Roslin makes a tough call: outlawing abortions but allowing any expectant mothers can bring their child to be adopted, no questions asked.

Newspaper Comics

 * One of the reasons Anthony is so despised in the For Better or For Worse fandom is the implied subtext that it was he who pressured his wife Thérèse into having a child that she didn't want by agreeing to be the primary care-giver, then reneging on the agreement just as Thérèse was going through postpartum depression. We are explicitly meant to see Thérèse as an unnatural monster for not wanting children in the first place (to the point where she wholesale abandons child, husband and all not much later) and Anthony as the poor put-upon hubby who 'tries to love' his wife despite her refusal to make them a 'real family'.

Poetry
"Dear my love, you know, You had a father: let your son say so."
 * The first 17 of Shakespeare's sonnets revolve around persuading a man that this applies to him.

Religion

 * In The Bible, mankind is ordered to "be fruitful and multiply," which has traditionally been seen as a command to have children if at all possible. The Patriarchs and Matriarchs, for example, went through a lot knowing that God's plans relied on them producing the Jewish people, as did Moses' parents in the wake of Pharaoh's decree.
 * Onan was killed by God for refusing to have a child with Tamar, his dead brother's wife, as per the laws of levirate marriage. Of course, he told her he would and then performed coitus interruptus to prevent it, so he was arguably sort of an Asshole Victim.

Tabletop Games

 * Exalted:
 * Terrestrials are strongly encouraged to marry and have babies regardless of sexual orientation, since theirs is the only sort of Exaltation that's hereditary.
 * Inverted with the Abyssals, who suffer divine (or at least infernal) punishment if they procreate. The Neverborn created them to get rid of all those pesky living creatures, damn it, not to go around making new ones!
 * A sore point for many fans of Werewolf: The Apocalypse is how werewolves are expected to marry kinfolk (humans who carry the recessive shapeshifter gene) and hopefully make werewolf babies, since lycanthropy is passed through plain old sexual reproduction in this game, regardless of whether or not either one has other plans. It's treated like Arranged Marriage at best and flat-out rape at worst.

Theater
"Lady, you are the cruel'st she alive If you will lead these graces to the grave And leave the world no copy."
 * In Twelfth Night, one argument used on Olivia.

"No! The world must be peopled. When I said I would die a bachelor, I did not think I should live till I were married."
 * In Much Ado About Nothing one argument used by Benedick on himself.

Video Games

 * In Fire Emblem: Genealogy of the Holy War, the fourth game in the series, every last female character recruited in the first half of the game has two kids if she falls in love with someone. One boy and one girl each, no exceptions. And it's a massive Generation Xerox for classes depending on who the fathers are.
 * While not strictly mandated, the Quarian race of aliens in Mass Effect, forced to live on an enormous fleet of mostly hand-me-down starships after having been exiled from their homeworld by their own robotic creations, and this trope may or may not be in effect depending on the state of the fleet. The Quarian Flotilla will occasionally be put into a state of overpopulation so they have incentives to have fewer children, and when they are underpopulated they will start giving things like tax breaks and other rewards to people who have multiple children. Fewer births is the norm though.

Webcomics

 * In Sinfest, Monique's body tries to argue with her.