Countries by fertility rate as of 2020
Chance of fertilization by menstrual cycle day relative to ovulation.
United States crude birth rate (births per 1000 population); Baby Boom years in red.

Capability to produce offspring through reproduction following the onset of sexual maturity.

- Fertility

500 related topics


Ansley J. Coale

One of America's foremost demographers.

The Demography of the World Population from 1950 to 2100. Data source: United Nations — World Population Prospects 2017

These model life tables both established new empirical regularities and proved invaluable in the development of later techniques for estimating mortality and fertility in populations with inaccurate or incomplete data.

Review of Economics of the Household

Peer-reviewed academic journal established in 2001 by Shoshana Grossbard and first published in 2003.

A reviewer at the American National Institutes of Health evaluating a grant proposal

Household decisions analyzed in this journal include consumption, savings, labor supply and other time uses, marriage and divorce, demand for health and other forms of human capital, fertility and investment in children's human capital, households and environmental economics, economics of migration, and economics of religion.

John Bongaarts

Dutch-American demographer.

Requests for use: Contact Population Council.

Bongaarts has performed research a broad variety of topics, such as: population ageing, fertility, population policy options, life expectancy.


Rabbits, also known as bunnies or bunny rabbits, are small mammals in the family Leporidae (which also contains the hares) of the order Lagomorpha (which also contains the pikas).

This image comes from a specimen in the Pacific Lutheran University natural history collection. It displays all of the skeletal articulations of rabbit's hind limbs.
The rabbits hind limb (lateral view) includes muscles involved in the quadriceps and hamstrings.
A Holland Lop resting with one ear up and one ear down. Some rabbits can adjust their ears to hear distant sounds.
Anatomy of mammalian ear
Rabbits use their large vascularized ears, which aid in thermoregulation, to keep their body temperature at an optimal level.
Ventral view of dissected rabbit lungs with key structures labeled.
Monopodial branching as seen in dissected rabbit lungs.
Diagram of the male rabbit reproductive system with main components labeled.
Diagram of the female rabbit reproductive system with main components labeled.
Domestic rabbit photographed at Alligator Bay, Beauvoir, France.
Impact of rabbit-proof fence, Cobar, New South Wales, 1905
Beatrix Potter's Peter Rabbit.
alt=A small, round, dust-coloured rabbit with upright, close-set ears sat on the ground amidst dead branches.|Brachylagus idahoensis{{pb}}Pygmy rabbit
alt=A model of a relatively large rabbit, with a slightly longer face and shorter, rounder ears, and fur patterned black and gold.|Nesolagus netscheri{{pb}}Sumatran Striped Rabbit{{pb}} (Model)
alt=A small, light-brown rabbit with upright ears sat on some grass.|Oryctolagus cuniculus{{pb}}European rabbit{{pb}} (Feral Tasmanian specimen)
alt=A taxidermy of a large rabbit with dark brown fur, small, thin ears and an elongated, rodent-like face.|Pentalagus furnessi{{pb}}Amami rabbit{{pb}} (Taxidermy specimen)
alt=A taxidermy of a very small light-brown rabbit mid-gallop. Its features are equally small, appearing similar to a vole.|Romerolagus diazi{{pb}}Volcano rabbit{{pb}} (Taxidermy specimen)
alt=A juvenile rabbit sat on a white person's hand; its fur is a light brown ticked heavily with dark brown. It is not quite large enough to fill the person's hand completely.|Sylvilagus aquaticus{{pb}}Swamp rabbit{{pb}} (Juvenile)
alt=A medium-sized rabbit with light brown fur ticked with grey, its ears large and upright. It stands on all fours on some sandy ground.|Sylvilagus audubonii{{pb}}Desert cottontail
alt=A light-brown rabbit sitting in a field, its body unusually large and squat, its limbs and head small, and its ears especially small|Sylvilagus bachmani{{pb}}Brush rabbit
alt=A taxidermy of a small rabbit, its fur a warm brown ticked with a darker brown, its ears small and set back, its face closer to a vole's than a rabbit's |Sylvilagus brasiliensis{{pb}}Tapeti{{pb}} (Taxidermy specimen)
alt=A rabbit sitting upright in a field, turning to face the camera, its fur a light brown ticked with grey and dark brown, its ears upright |Sylvilagus floridanus{{pb}}Eastern cottontail

Rabbits are often used as a symbol of fertility or rebirth, and have long been associated with spring and Easter as the Easter Bunny.


Nonylphenols are a family of closely related organic compounds composed of phenol bearing a 9 carbon-tail.

Structure of the hormone estradiol and one of the nonylphenols.

Nonylphenol causes the feminization of aquatic organisms, decreases male fertility, and decreases survival in young fish.

Billings ovulation method

An observation chart.

The Billings ovulation method is a method in which women use their vaginal mucus to determine their fertility.


Absence of one or both testes from the scrotum.

Cryptorchidism on scrotal ultrasound
Scrotal ultrasonography of undescended testis: (a) Normal testis in the scrotum (b) Atrophic and decreased echogenicity of the contralateral testis of the same patient seen in the inguinal region
Inguinal cryptorchidism in a Chihuahua
A retained testicle with cancer removed during necropsy of a dog
Genitals of a 42-year-old man with cryptorchidism. The empty scrotum is clearly visible. The two bumps, that are above penis in pubic zone can be seen too, these are the testicles in the inguinal canal

Undescended testes are associated with reduced fertility, increased risk of testicular germ-cell tumors, and psychological problems when fully-grown.


Form of body modification made by inserting tattoo ink, dyes, and/or pigments, either indelible or temporary, into the dermis layer of the skin to form a design.

A realism styled tattoo depicting an owl and dreamcatcher.
A sailor's forearm tattooed with a rope-and-anchor drawing, against the original sketch of the design
An example of a tattoo design
Application of a tattoo to a woman's foot
Spanish depiction of the tattoos (patik) of the Visayan Pintados ("the painted ones") of the Philippines in the Boxer Codex (c.1590), one of the earliest depictions of native Austronesian tattoos by European explorers
A Māori chief with tattoos (moko) seen by Cook and his crew (drawn by Sydney Parkinson 1769), engraved for A Journal of a Voyage to the South Seas by Thomas Chambers
Tattooing among women of the Koita people of Papua New Guinea traditionally began at age five and was added to each year, with the V-shaped tattoo on the chest indicating that she had reached marriageable age. Photo taken in 1912.
An identification tattoo on a survivor of the Auschwitz concentration camp
Tattoo marking a deserter from the British Army; skin removed post-mortem
Tattooed lip makeup
Medical tattoo: blood type
Samoan pe'a, traditional male tattoos
Whang-od, the last mambabatok (traditional Kalinga tattooist) of the Kalinga in the Philippines, performing a traditional batek tattoo.
Giolo (real name Jeoly) of Miangas, who became a slave in Mindanao, and bought by William Dampier together with Jeoly's mother, who died at sea. Jeoly was exhibited in London in 1691 to large crowds as a sideshow, until he died of smallpox three months later.
A portrait of Omai, a tattooed Raiatean man brought back to Europe by Captain James Cook.
A 19th century drawing of a tattooed Bosnian Croat woman.
Sailor being tattooed by fellow sailor aboard USS New Jersey in 1944
Fred Harris, Tattoo Studio, Sydney, 1937
Artists place the artwork on the body in the form of a stencil to guide the process.
A two coil tattoo machine
Mrs. M. Stevens Wagner with arms and chest covered in tattoos, 1907
An 1888 Japanese woodblock print of a prostitute biting her handkerchief in pain as her arm is tattooed. Based on historical practice, the tattoo is likely the name of her lover.
Wilfrid Derome Tatto Collection, 1925
Latin Kings gang member showing his gang tattoo
Modern tattoo artist's nitrile gloves and sterilized equipment
Decal temporary ambigram tattoo Love / eros, on wrists
A henna temporary tattoo being applied
Dermatitis due to a temporary tattoo (dolphin) made with black henna
A Christian couple with matching cross symbol tattoos to associate with their faith
Keloid formation at the site of a tattoo

Many tattoos serve as rites of passage, marks of status and rank, symbols of religious and spiritual devotion, decorations for bravery, marks of fertility, pledges of love, amulets and talismans, protection, and as punishment, like the marks of outcasts, slaves and convicts.


Primary sex hormone and anabolic steroid in males.

Human steroidogenesis, showing testosterone near bottom
Hypothalamic–pituitary–testicular axis
Reference ranges for blood tests, showing adult male testosterone levels in light blue at center-left
Nobel Prize winner, Leopold Ruzicka of Ciba, a pharmaceutical industry giant that synthesized testosterone
Dimeric sex-hormone-binding-globulin with its testosterone ligands
Two methods for determining the concentration of bioavailable testosterone.

Growth of spermatogenic tissue in testicles, male fertility, penis or clitoris enlargement, increased libido and frequency of erection or clitoral engorgement occurs.


Chemical compound with the formula C6H23CH3.

Cross-sectional view of Oerlikon 20 mm cannon shells (dating from c. 1945) showing color codes for TNT and pentolite fillings
Chunks of explosives-grade TNT
Trinitrotoluene melting at {{convert|81|C|F}}
M795 artillery shells with fuzes fitted, labelled to indicate a filling of TNT
M107 artillery shells. All are labelled to indicate a filling of "Comp B" (mixture of TNT and RDX) and have fuzes fitted
thumb|Analysis of TNT production by branch of the German armed forces between 1941 and the first quarter of 1944, shown in thousands of tons per month
Detonation of the 500-ton TNT explosive charge as part of Operation Sailor Hat in 1965. The passing blast-wave left a white water surface behind and a white condensation cloud is visible overhead.

There is evidence that TNT adversely affects male fertility.