The female and herm HUDs allow a great deal of configuration of fertility elements. To reach them, activate the main menu and select the "Womb" button.
Current will display the present womb configuration in plain English. E.g.:
One SL "day" equals 4 hours in RL. All other values are stated in terms of this rate.
* Menustral cycles last 4 weeks, +/-1 day, 23 hours
* Menstruation lasts about 4 days, 11 hours, and the fertile period is from about days 11 through 18.
* If ovulation occurs immediately after insemination, there is a 35% chance of conception for each ovum.
* Chances of multiple ovulation are: 1 ova (always), 2 ova (1 in 17), 3 ova (1 in 1600)
* If conception occurs, gestation will end 12 weeks after the beginning of the menstrual cycle, +/- 4 days
Default will reset the configuration to the default parameters (human, normal fertility, gestation length, etc.)
The remaining items open a submenu.
Submissive mode permits coupling by nearby avatars without your consent. While this is appropriate for many scenarios, such as capture role-play, it creates the possibility that your "partner" may perform what's known as a "drive-by," simply attempting to inseminate then run off to his next target without following through on the role play.
As such, you can set a grace period during which you can abort coupling, and your partner can not inseminate you. You'll be notified of the attempt, and your partner will be notified that he was unsuccessful.
The insemination grace period applies regardless of whether submissive mode is set.
In most regions (sims), there is a four-hour day, as defined by the sunrise-to-sunrise period. All elements of the simulation are scaled to this ratio.
Changing day length will also automatically adjust the duration of your cycle or a pregnancy in progress.
You can choose to have virtual time advance more quickly while you are online (and your HUD is attached). This can be used to quickly advance the HUD's stage (e.g., to rapidly progress through your cycle or a pregnancy), or to allow yourself more time within a stage.
Use this feature with caution, as it can interfere with some elements of HUD operation (such as conception). It is generally better to adjust your day length.
This menu contains options specific to HUD operation within your monthly cycle
You can vary the duration of your cycle. The normal value is 28 days.
Keep in mind that gestation officially begins at the beginning of the cycle in which you conceive, so consider your cycle length if you choose a different length for gestation (below). E.g., if you choose a 56-day cycle and an 84-day pregnancy, the pregnancy will only last about 28 days beyond the end of your cycle. That value is even less when you consider that your cycle will generally appear to run a bit long if you conceive (unless you take a home pregnancy test and receive a positive result).
You can specify when during your cycle that you are fertile. The fertile period is defined as the time during which you may ovulate, not necessarily the time during which you may become pregnant simply due to insemination. As such, increasing the fertile period only has the effect of increasing the time of uncertainty.
The default fertile period is the middle 25% ("week") of your cycle, roughly days 11 through 18.
The fertile period also affects the time during which reflex ovulation is possible. See "Fertility - Reflex Ovulation," below.
The only element of gestation that may be configured is its duration. Once a pregnancy begins, its length (in SL days) may not be altered. If you wish to "modify" a pregnancy, use acceleration, change your day length, or ask another user with the Physician's HUD to terminate it (as the last resort).
Remember that the gestation length includes the time spent in the cycle.
This menu presents further options related to fertility.
This menu allows you to specify the conception rate for each egg (ovum). The default is 35%.
This value represents the likelihood that an egg would be fertilized if insemination occurred just prior to ovulation. If insemination occurs halfway during the egg's lifetime (about 1.5 "days"), this rate would effectively be halved. As such, this represents the conception rate if a couple is trying or the womb is frequently inseminated (such that sperm is always present).
1% roughly corresponds to the rate of conception if birth control were being used (although the HUD tends to assume a certain degree of carelessness). While birth control in real life actually results in the prevention of ovulation, the HUD simulates this by reducing the chance of conception (mainly for historical reasons). As such, birth control pills may be simulated using the "Release" menu in future versions (see below).
99% almost always results in conception provided you are trying.
Normally, only one egg is released at the time of ovulation. Occasionally two or even three are released, resulting in fraternal twins or triplets. You can alter this likelihood to correspond to several predetermined scenarios:
Normal - normal human ovulation. At least one egg will be released during each cycle. There is roughly a 1-in-17 chance of two eggs, and a 1-in-1600 chance of three, which roughly represents the real-world statistics on multiple live births.
Clomid - Increased odds of multiples, 1-in-3 for two eggs, and 1-in-33 for three
IVF Meds - Dramatically-increased odds of multiples, as real-life IVF medications are intended to increase egg production with the intent of removing the eggs prior to fertilization. Obviously, no eggs will be removed in this scenario. Generally, 5-10 eggs will be released.
Canine - 1-10 eggs, but generally around 5-6
Feline - 1-6 eggs, generally around 3-4
Lagomorph (rabbits and similar) - 1-10 eggs, generally around 7-8.
Remember that each egg is separately fertilized, so it's possible to be carrying children of more than one father!
Reflex fertilization is a phenomenon that occurs commonly in the animal kingdom, especially among prolific species such as rabbits, as well as among many domesticated animals such as cats and dogs.
When this option is enabled, ovulation will not occur randomly within the fertile period. Instead, ovulation will occur the first time you couple within your fertile period, and not again until your next cycle (provide you fail to conceive). This obviously maximizes the chances of conception provided you are inseminated shortly after coupling.