Pregnancy

Pregnancy is a game mechanic and multiple-day event that begins after a successful 'Try for Baby' interaction between two Sims of opposite sex, and ends with the pregnant female Sim giving birth to one or more newborn children. Pregnancy primarily affects adult and young adult  female Sims. Pregnancy brings many physical and lifestyle changes to the pregnant Sim, including increasing body size, faster-decreasing motives, and forced vacation/maternity leave from work.

Pregnancy was introduced as a game feature in The Sims 2, and has appeared in each subsequent game. Prior to The Sims 2, kissing or playing in bed were the only interactions that could result in two Sims having a child - and the player could usually say yes or no to that. If the player said "yes", or was not given that option, a baby would immediately appear, forgoing any pregnancy period.

Under normal circumstances, only female Sims can become pregnant. However, male Sims can be impregnated as well, either through Alien abduction or by the use of Cheats.

Conception
To get a Sim pregnant, the two partners must "Try for Baby". When trying for a baby, there is a possibility that the Sim will not get pregnant, but if she does then the player will hear a lullaby song or jingle, signaling a successful conception.. In The Sims 4, the lullaby song was removed, and Sims can use the pregnancy test on the toilet.

In The Sims 2, only Adults and Elder males can initiate Try for Baby, although the InTeenimater mod can allow teens to become pregnant. (While Young Adult males can father children with Adult females, the "Try for Baby" interaction must be initiated by the Adult female at her home.) If the Sim is infertile, the player can testingcheatsenabled and spawn the Tombstone of Life and Death to impregnate a Sim. The number of babies born is determined at conception, but the gender is determined at birth.

Male young adults, adults, and elders can try for a baby, but only female young adults and adults can get pregnant. Additionally, the chance of conception is lowered for older female Sims trying for a baby.

Depending on what the player does or exposes the mother to during her pregnancy, it will affect both the gender and number of offspring the pregnancy will produce.

In The Sims Medieval, Woohoo between two Sims of the opposite gender always carries a chance of pregnancy; there is no "Try for Baby" option.

The Sims 2
In The Sims 2, when an adult male stargazes with the Farstar e3 telescope at night, there is a chance that he will be abducted by aliens. If he is, he will return after a few Sim hours, and will soon learn that he is pregnant. (Female Sims and male Sims of different ages can be abducted, but only adult males will become pregnant as a result of an abduction.) If NightLife is installed, an adult male Sim abducted from the ElectroDance Sphere will return pregnant. The Nightlife patch fixed a glitch which allowed young adult males abducted from the ElectroDance Sphere to return pregnant.

If FreeTime or later is installed, Knowledge Sims with the Summon Aliens aspiration benefit can use either telescope to attempt to summon aliens; so an adult male Sim with that benefit can use it to attempt to become pregnant.

The Sims 3: Seasons
There's a 33% chance a young adult or older male who has been abducted by aliens may receive the "Unexpected Weight Gain" moodlet after the "Abducted" moodlet has expired. While the Sim will give birth after the "Unexpected Weight Gain" moodlet has expired, he is not otherwise treated as pregnant. He will not be given maternity leave, will not change into maternity clothes, will not be restricted from activities that pregnant Sims normally cannot do, and will not pass on any genetic information to the alien child.

It has been noted that this can only happen if the aliens performing the abduction are not residents of the neighborhood.

Vacation Romance
In The Sims 3: World Adventures, it is possible for a Sim to have WooHoo with someone from the place they are visiting on their holidays. If a male Sim were to WooHoo with a female Sim who lives in his holiday destination (i.e. China, France or Egypt), it is possible for the female Sim to get pregnant. But when the male Sim returns home, his offspring can be seen on the family tree as a child, even if the WooHoo occurred the previous day. This jump in age occurs due to the fact that pregnant females, babies, and toddlers are not present in foreign destinations. In addition, Story progression is at a catch-up rate, meaning the offspring will not immediately show any age progressions through the family tree. Meanwhile, a female Sim who does the same will return home and give birth to the child, and the family tree will show who the father is; the baby will grow up in a normal pace.

The Sims 4: Get To Work
Theres a chance during the hours of 9PM - 4AM that a Sim can be abducted, Male Sims after abduction may come back with the pregnant with an Alien baby where as Female sims will only get the Abducted moodlet.

Duration
Pregnancies last 75 Sim hours in The Sims 2 and 72 Sim hours in The Sims 3 though it's common to refer to pregnancies as lasting 3 days in both games. In The Sims 4, pregnancies can last up to 3–5 days. The Sims 2 has cheats which can be used to reduce the gestation period to a mere 2 hours of Sim time. The lifespan setting in The Sims 3 does not normally affect the duration of a pregnancy.

The motives of a pregnant Sim will drop at an increased rate, even if the Sim is not visibly pregnant. In The Sims 2, Sims who are able to meditate will still be able to do so while pregnant.

In The Sims 2, it is possible to calculate the time in which the Sim will expand each day and eventually give birth. From the hour in which a Sim becomes pregnant, she will expand 25 Sim hours later each day until she gives birth. So a female who becomes pregnant at one o'clock on Tuesday, will expand at two on Wednesday, three on Thursday, and give birth at four on Friday.

In The Sims 3, a Sim who is at level 5 or higher in the Medicine career track can determine the gender of the baby.

First Trimester
The first trimester lasts one day only. During this trimester the pregnant Sim will suffer from morning sickness, which usually leads them to throwing up in the bathroom, with a thought bubble showing a pacifier and a question mark. In The Sims 2, Sims with high Body skill may have a better chance of not throwing up, though they will still be visibly queasy, and their Comfort meter may at times go into the red. Sims do not always throw up when pregnant, but they may wake up in the middle of the night to vomit.

In The Sims 2, the Sim will not be visibly pregnant. In The Sims 3, the bulge cannot be seen unless the player zooms in. Sims with the Grumpy trait will be aggravated by morning sickness. During the first trimester, the pregnant Sim can't leap into other Sims' arms and other Sims can't leap into her/his arms.

Also, pregnant Sims in The Sims 2 may have random drops in the hunger motive, which may take newer players by surprise.

In The Sims 4, the player can have the prospective mother do a pregnancy test after trying for a baby. This is done by selecting the action at the toilet. If the Sim is pregnant, a "First Trimester" moodlet will appear, and will last 24 hours. When a pregnancy test is not done the Sim will appear pregnant around 24 hours after conception.

Second Trimester
The second trimester lasts one day. At some point in the day, the pregnant Sim will attract the player's attention and change appearance. Their abdomen will enlarge and they will begin to wear maternity clothing. In The Sims 3, the bulge is nearly non-existent at first, but progressively grows larger. If the pregnant Sim has a job, they will be placed on maternity leave, and the carpool will not appear. In The Sims 2, however, a pregnant Sim who has access to a car can drive to work. In The Sims 2, the Sim will be paid for these leave days even if they fall on one of their days off. Also, in The Sims 2, calling a Sim who is on maternity leave during his or her work hours will still result in the " is working" messages, and a Sim who "brings a friend" home from work may bring a pregnant Sim. There will be new social interactions, "Rub Belly" and "Talk to Belly" ; "Feel Tummy", "Listen to Tummy", and "Talk to Tummy", and the pregnant Sim may "Ask to Feel Tummy". The pregnant Sim and father can announce the pregnancy to others.

In The Sims 2, a Sim at this point will no longer be able to do yoga or work out in front of a stereo, but will be able to work out in front of a television. The Sim may be able to use some types of exercise equipment, but will not be able to use all types. The combined effects of pregnancy and working out will be hard on the Sim's motives, but this does not appear to pose any other risk. A pregnant Sim will be able to swim, but will be unable to use a diving board or pool slide.

Pregnant Sims in the second and third trimesters can also expect to have cravings, in the form of more "Eat..." wants/wishes (depending on which game) for specific foods. These are easy to fulfill, since they'll usually be a dish the Sim knows how to cook.

In The Sims 4, a Sim in the second trimester may get a Morning Sickness moodlet upon waking from sleep. This which will make them Uncomfortable, and possibly even make them throw up.

Third Trimester
The third trimester lasts one day. The expectant Sim will get the attention of the player and the abdomen will enlarge again. They can no longer drive, take a taxi, use the swing, or use the electro-dance sphere from Nightlife. They will suffer from mood swings, in which the outcome of Social interactions between the pregnant Sim and another will change. In The Sims 3, they will get negative moodlets, such as the "sore" moodlet, and may no longer run.

In The Sims 4, the third trimester can last 1 or more days, as birth can happen at any time rather than at a set time as in previous games.

Birth
On the last day of the pregnancy the Sim will attract the viewer once again and go into 'labor'. This is an autonomous action and all Sims on the lot or nearby will be drawn to the Sim to 'panic'. In The Sims 3 and in The Sims 4: Get to Work expansion, the pregnant Sim can be taken to the hospital when clicked on while in labor, or they can stay at home, and have a safe and comfortable birth.

In The Sims 2, a screen will come up with the message "There's a new family member on the way..." or "There are TWO new family members on the way..." (if the Sim is having twins) at which time the genetics and gender of the new baby (or babies) are determined. If the special camera is enabled, a cinematic will commence showing the birth of the baby, otherwise the Sim will turn around on the spot and a new family member is born. If the Sim has a job, they will get additional leave in the form of three vacation days, regardless of the number of vacation days they already have. These work like ordinary vacation days; if the Sim is scheduled to work, the carpool will come, and the Sim will get in unless the player cancels that action. These vacation days will not be lost if they are not used while the new family member is a baby. If another family member can stay home with the baby, the player may want to let the Sim go to work in order to save a leave day for later.

In The Sims 3 a little pop-up will say: "The baby is coming! Make sure (Sim) is at home or in the hospital so she can have a safe and comfortable birth!" If the Sim goes to the hospital, the player won't be able to see anything, but can still hear the birth taking place. If the Sim stays at home, the Sim will turn on the spot, and the new little family member will be born there.

In The Sims 4 labor lasts several hours. The Sim can continue to do things while in labor but will be Uncomfortable. If the player bought a bassinet previously, the Sim will go to the bassinet to give birth when the time comes. If they didn't, a bassinet will spawn spontaneously when the baby is born.

After the birth of the baby (or babies), the player will then be able to name them. In The Sims 3, depending on how happy the mother was during her pregnancy, the player might be able to choose both traits for the baby, just one, or none at all.

Multiple Births
The Sims 3 allows for the birth of both twins and triplets. The Sims 2 only allows for twins, though there are third-party hacks which can produce triplets and quadruplets.

Twins
Twins are conceived the same way as single babies, so they will look about as much like each other as normal siblings do—from nearly identical to widely different. With, for example, a light-skinned mother and dark-skinned father, the twins can have different skin colors. However, some pre-made twins, such as the Pleasant twins, are identical; and it's possible to make identical Sims in CAS. CAS in The Sims 3 even has a Create A Twin option, which creates an identical copy of a Sim.

Every pregnancy has a low chance of producing natural twins. Most Sims have about a 10% chance of having twins, although if a parent is a twin themselves, the chances increase slightly. This is decided at the moment of conception, so, unlike gender and genetics, exiting and reloading the lot will not change the number of babies born. However, with the Open for Business expansion pack for The Sims 2, EA did include a "forcetwins" cheat; using it when a pregnant Sim is selected will result in that Sim having twins. If a pregnant Sim eats cheesecake, also added in Open for Business, they will have twins, as if the "forcetwins" cheat had been used while they were selected. This is different from what is stated in the Prima guide for Open for Business; the guide states that eating cheesecake while pregnant increases the chance of twins, not that it ensures them.

There was a myth that eating cheesecake prior to conception would increase the chance of having twins. Whether or not this is what EA originally intended, it is not true.

Enabling testingcheatsenabled and shift-clicking a pregnant woman allows the player to force twins by clicking on DEBUG: force twins.

Triplets/Quadruplets
Under normal circumstances, it is impossible to have triplets, quadruplets or more in The Sims 2. Players may download third-party hacks to obtain the option of having triplets or quadruplets. When having triplets or quadruplets, the game informs players that the Sim in question has given birth to two babies, despite the actual number. Players are still able to name each child, though, as the option pops up twice.

In The Sims 3, a player can use the Fertility Treatment to get twin and triplets, but not quadruplets. Players may download third-party hacks to obtain the option of having quadruplets.

Increasing Multiple Birth Odds

 * The Sims 2
 * The cheat "forcetwins" will give the Sim a 100% chance of twins.
 * A pregnant Sim can eat cheesecake, which gives a 100% chance of twins.
 * The ultimate Lifetime Aspiration Benefit for Family Sims is Super Fertility, which greatly increases the chance of having twins for the rewarded Sim and their spouse. The benefit will decide the number of children born 25 hours after conception (at the time of the first belly expansion).
 * There is also a chance that twins will carry down in the family tree such as the case of Antonio Monty with his children as Antonio may, himself, be a twin to his deceased brother.
 * With the InSimenator, a player can buy the Reproductive Adjustor, which looks like a microwave oven. If the player selects a pregnant Sim and clicks on the Reproductive Adjustor, one of the options will be to select the number of babies.


 * The Sims 3
 * Watching the kids channel on TV or listening to the children's music station on the stereo can increase the chance of multiple children. Doing either slightly increases the chance for multiples. Doing both at the same time more than doubles the chances of having twins or triplets as either alone.
 * Reading the pregnancy book. One or both parents can read it to have a better chance of outcome.
 * Having the "Fertility Treatment" lifetime reward. Fertility Treatment makes it more likely that "Try For Baby" will work, and also increases chances of twins and triplets.
 * Sims can wish for Large Family from the genie and get the "Feeling Fertile" moodlet, which will give them twins or triplets when trying for baby.
 * Sims can use the Procreation Elixir. They will get "A Twinkle in the Eye" moodlet, lasting for 8 hours, that increases the chances of conception and having twins or triplets. This effect is the same as having the "Fertility Treatment" lifetime reward. The reward and elixir effects will not stack.
 * Using the romantic massage from the massage table, gives Sims "High Fertility" moodlet that increases the chance of having twins or triplets.

The Sims
There is no pregnancy in The Sims, but if a family is evicted while there is a baby in the house, the baby will be lost.

The Sims 2
Miscarriage per se does not occur in The Sims 2, but if a pregnant Sim dies, the baby will be lost, as in the case of Olivia Monty's unborn baby. Family members will not get a memory of losing the baby, only the Sim who died.

If a pregnant Sim becomes an elder, the baby will be lost. Normally, a Sim who is close enough to elder-hood for that to happen cannot become pregnant. However, negative effects of drinking the Elixir of Life can age a pregnant Sim to the point where it becomes possible, or even move the Sim into the Elder life stage.

In addition, there are hacks which can be used to end a pregnancy.

The InTeenimater
With the InTeenimater, a mod for The Sims 2, the player can make a miscarriage when a Sim is pregnant. She will have a miscarriage in her memories. The PlumbBob will glow red, and the Sim will start grasping for her stomach. A thought bubble with a pacifier and a question mark will come up. The Sim will then be in her normal clothes, and start crying.

The pregnancy may even end with a miscarriage (autonomously), if the pregnant Sim's motives are low, specifically hunger and energy.

The player may also choose an option known as "End Pregnancy" which will stop the pregnancy completely, meaning that the Sim will lose the baby but will have no emotional distress or memories of losing the baby.

The InSimenator
With the InSimenator, a player can buy the Reproductive Adjustor, which looks like a microwave oven. If the player selects a pregnant Sim and clicks on the Reproductive Adjustor, one of the options will be "Abort Pregnancy". Aborting a pregnancy sometimes makes the mother depressed. Another option on the Reproductive Adjustor is "Suspend Pregnancy", which will pause the pregnancy until the Reproductive Adjustor is used to resume it.

The Sims 3
In The Sims 3, it is not possible for a pregnant Sim to lose the baby, without any cheats. In The Sims 3, if a Sim is impregnated or turns pregnant before becoming an elder, the process of aging is simply suspended until after the baby is born. It also appears that pregnant Sims in The Sims 3 cannot die, and will avoid or survive events that would normally result in death, even if those events are arranged by the player. Sims who have successfully conceived, but haven't realized they are pregnant, cannot die as well. There are many mods that will stop a pregnancy, however most of them don't have any negative effects on the Sim. If the player clicks on the pregnancy moodlet while pressing the Ctrl key with testingcheatsenabled on, it will not stop the pregnancy but simply deny the mother a happy moodlet during her entire pregnancy. If this happens to the "Baby Is Coming!" moodlet, the mother will remain pregnant but never give birth until the game is restarted.

In several pregnancy mods, there are varying "End Pregnancy" options, some giving moodlets such as "Broken Heart" or "Strained".

The Sims 2
There is currently no definitely known way to influence the gender of an unborn child in The Sims 2. The only way to change the outcome is if the player saves while the mother is going through the labor animation, (or any time during pregnancy) before the "new baby on the way" popup comes up and the birth cutscene begins. If, after the birth, the baby is not the desired gender, the player can exit the lot without saving and go through the sequence again; this can be repeated until the baby is the desired gender. Since the chance of getting either gender is about 50%, this can take any number of tries to succeed.

No Maxis cheat or fan-made hack exists to force a gender, though there have been many rumors, none of which are true. These include a fake "boolprop force[gender] 100" or the "twinsr2cute" cheats. Another rumor is that if a pregnant Sim eats gelatin it will increase the chance for a girl. It has also been rumored that the baby will be a boy if the father initiates the "Try For Baby" action, and will be a girl if the mother initiates it. However, this has been disproven.

The Sims 3
In The Sims 3, there are ways to increase the chance to have male or female babies. Eating 3 or more apples during the pregnancy in each trimester will greatly increase the chances for the baby being a boy, while 3 or more watermelons during each trimester will greatly increase the odds of having a girl. If the Sim is carrying twins or triplets, there is still a chance that both boys and girls will be born.

Patch 1.3 of The Sims 3 keeps the apples for boys, watermelons for girls system, however eating these in prepared foods will not affect the gender. For example, watermelon pancakes will not increase the chances for a girl.

There are many mods that allow the players to choose a baby's gender or tweak the chances in one direction or the other, but these mods all have their own rules and may not be subject to information given here.

The Sims 4
It is not possible to control or affect a baby's sex in an un-updated copy of The Sims 4. Patch 17 (released on May 4, 2015) introduces a method for influencing the gender of offspring. Eating strawberries or listening to Pop music will increase odds for having a girl, while eating carrots or listening to Alternative music increases the likelihood of having a boy.

Pets
Like Sims, female pets are able to become pregnant and give birth.

The Sims: Unleashed
Pets, like Sims, cannot become pregnant per se. However, if a male and female pet have a good relationship, they can "snuggle", which can lead to the player being asked whether or not they should have a kitten/puppy. Once the kitten/puppy is born, there will be a small box with a sheet over it near the mother, and the Sim(s) will "welcome" it by clapping at it. The kitten/puppy cannot be fed or played with, only viewed by Sims (while pets watch it), so when it comes to taking care of it, the player has to make sure the mother is doing okay. If not, then animal control will come to take the kitten/puppy away. After 3 Sim days, the kitten/puppy becomes fully grown. Pets born in-game have no personality points.

The Sims 2: Pets
In The Sims 2, a Sim can command a pet to WooHoo in a large pet house with another pet of the opposite gender, provided that the Sim has a good relationship with the pet being commanded and the two pets have a good relationship with each other. The female pet stays pregnant for three days, and then has the kittens/puppies. Kittens and puppies in The Sims 2 can do things, and Sims can interact with them, unlike in Unleashed. Kittens and puppies cannot get jobs nor learn commands, but they can learn behaviors.

The Sims 3: Pets
Pet pregnancy in The Sims 3 is mostly the same as in The Sims 2, with the exception of horses, as they are a new addition. Horses can breed in a box stall or be taken to the equestrian center and bred with a horse of the player's choosing. There is also a Lifetime Reward available for all cats and dogs that will increase the number of kittens or puppies that they have at once.

Other

 * Pregnant Sims get a few days off work (maternity leave).
 * In The Sims 2, the days off are counted as calendar days. The Sim is paid for a day whether or not he/she was scheduled to work that day, so it is effectively bonus pay. The message saying that the Sim has used a paid vacation day does not appear, even if the Sim was scheduled to work that day. Also, a pregnant Sim who drives or walks to work will still receive this pay in addition to being paid for a day's work.
 * In The Sims 3, the days off are counted as work days and not calendar days. This means that a female astronaut Sim who gets pregnant winds up getting weeks off in maternity leave due to there only being 1 working day a week).
 * Parents get a few days off when they adopt a baby.
 * In The Sims 2, a visibly pregnant Sim can get a job, but the "new job" pop-up notice will say that the Sim should not start work until after the baby is born. The Sim will not receive paid maternity leave for this time, but will otherwise be treated as a Sim on maternity leave.
 * In The Sims 2, a Sim who gives birth to twins will change out of maternity wear after the first baby is born.
 * Pregnant Sims experience nausea and backaches, shown as negative moodlets.
 * Fulfilling a pregnant Sim's wishes improves the chances of a "happy" pregnancy, which will give the child better traits or even allow the player to select the traits. If a pregnant Sim and the father read pregnancy books the chances of a "happy" pregnancy improve, in addition to the improvement given by any wants the Sim may have to do so.
 * A Sim in the medical career (level 5 or above) can "Determine the Gender of Baby" of the pregnant Sim and can "Give Medical Advice". Clicking on the hospital allows the interaction "Get Medical Advice". They will enter the hospital and then come out after a while. This option is not available with Sims that are not pregnant.
 * If the father is on a different lot or even at work when a Sim goes into labor, he will go to the hospital to be with the mother.
 * If both the mother and the father have the Fertility Treatment Lifetime reward, there is a high chance the Sim will get twins or triplets.
 * Sims can "Try For Baby" in a time machine, and the result will be a child of the couple; who is an elder if the player initiates "Try For Baby" in the future and in the past soon after, or a teenager/young adult when done the other way round.
 * Pregnant Sims can't change their appearance.
 * In The Sims 3, pregnant Sims cannot become vampires.
 * In The Sims 3: Supernatural, Sims can't transform to their werewolf-form while they are pregnant.
 * If a pregnant Sim goes on vacation before starting to show or becomes pregnant while on vacation, the pregnancy will be suspended until after they return home. The Sim may, however, experience morning sickness when on the rental or hotel lot, especially on a longer vacation.
 * Pregnant Sims cannot clean a litter box.
 * In The Sims 3, before the Sim is visibly pregnant, it is possible to customize the maternity clothing.
 * Young adults that are pregnant and about to become adults will not age up until the baby is born.
 * In The Sims 3: Island Paradise, mermaids will still be able to transform into their mermaid state while in the ocean or pool.
 * In The Sims 3: Island Paradise, mermaids aren't able to snorkel, dive, or windsurf while pregnant. However, they can still ride boats.
 * Pregnant Sims will not change into a costume during a costume party.
 * A pregnant Sim cannot travel to the future.  However, they can get pregnant and have a baby in the future, but the household will not be able to return home while the Sim is pregnant.
 * In The Sims 4, pregnant Sims no longer change into maternity clothes, as Sims can wear any clothes while pregnant.

Player tips

 * Speed up pregnancy with the Tombstone of Life and Death and it will take about three Sim hours (minutes in real time if at speed 1) for the baby to be born.
 * You can save your game before a Sim gives birth and then exit and reload if you want to try getting a baby of a different gender.
 * The quickest and easiest way to get a female Sim pregnant is by making her tour the Theater with her spouse/boyfriend. Once they are inside click the option "Try for Baby Backstage" and "WooHoo Backstage". There is the rare occasion of which the couple will be caught and thrown out. This is the best way to get your Sims pregnant because there is no flirting and kissing, so it doesn't take as long.
 * Fathers-to-be in The Sims 3 can assist during pregnancies by massaging a pregnant Sim's aching back, cooking for their cravings and reading pregnancy books.
 * To make the expectant mother happy during her pregnancy, try to fulfill her wishes, and make sure she gets massages when she's having back pain. Go to the hospital to receive medical advice, make both parents read books about pregnancy and don't forget to keep the mother in a good mood.