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Fertility is the capability to produce
offspring In biology, offspring are the young creation of living organisms, produced either by a Asexual reproduction, single organism or, in the case of sexual reproduction, two organisms. Collective offspring may be known as a brood or progeny in a more ...

offspring
through
reproduction Reproduction (or procreation or breeding) is the biological process Biological processes are those processes that are vital for an organism In biology, an organism () is any organic, life, living system that functions as an indivi ...

reproduction
following the onset of
sexual maturity Sexual maturity is the capability of an organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxono ...
. The
fertility rate The total fertility rate (TFR) of a population is the average number of children that would be born to a woman over her lifetime if: # she was to experience the exact current age-specific rates (ASFRs) through her lifetime # she was to live from ...

fertility rate
is the average number of children born by a female during her lifetime and is quantified
demographically
demographically
. Fertility is addressed when there is a difficulty or an inability to reproduce naturally, which is referred to as
infertility Infertility is the inability of a person, animal or plant to Sexual reproduction, reproduce by natural means. It is usually not the natural state of a healthy adult, except notably among certain eusocial species (mostly haplodiploid insects). I ...
. Infertility is widespread, with fertility specialists available all over the world to assist mothers and couples who experience difficulties having a baby. Human fertility depends on factors of
nutrition Nutrition is the biochemical and physiological process by which an organism uses food to support its life. It includes ingestion, Absorption (biology), absorption, Assimilation (biology), assimilation, biosynthesis, catabolism and excretion. ...
,
sexual behaviour Human sexual activity, human sexual practice or human sexual behaviour is the manner in which humans experience and express their sexuality Human sexuality is the way people experience and express themselves Human sexual activity, sexual ...
,
consanguinity Consanguinity ("blood relation", from Latin '':wikt: consanguinitas, consanguinitas'') is the characteristic of having a kinship with another person (being descended from a common ancestor). Many jurisdictions have laws prohibiting people who ar ...

consanguinity
,
culture Culture () is an umbrella term which encompasses the social behavior and Norm (social), norms found in human Society, societies, as well as the knowledge, beliefs, arts, laws, Social norm, customs, capabilities, and habits of the individuals i ...

culture
,
instinct Instinct is the inherent inclination of a living Living or The Living may refer to: Common meanings *Life, a condition that distinguishes organisms from inorganic objects and dead organisms ** extant taxon, Living species, one that is not extinct ...
,
endocrinology Endocrinology (from ''endocrine The endocrine system is a messenger system comprising feedback loops of the hormone A hormone (from the Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδ ...
, timing,
economics Economics () is a social science that studies the Production (economics), production, distribution (economics), distribution, and Consumption (economics), consumption of goods and services. Economics focuses on the behaviour and interact ...

economics
, way of life, and
emotion Emotions are psychological state A mental state is a state of mind that an agent is in. Most simplistically, a mental state is a mental condition. It is a relation that connects the agent with a proposition. Several of these states are a comb ...

emotion
s. Fertility differs from
fecundity Fecundity is defined in two ways; in human demography, it is the potential for reproduction of a recorded population Population typically refers the number of people in a single area whether it be a city or town, region, country, or the wor ...
, which is defined as the ''potential'' for reproduction (influenced by
gamete A gamete ( /ˈɡæmiːt/; from Ancient Greek Ancient Greek includes the forms of the Greek language Greek ( el, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referred to by speakers simply ...
production, fertilization and carrying a pregnancy to term). Where a woman or the lack of fertility is
infertility Infertility is the inability of a person, animal or plant to Sexual reproduction, reproduce by natural means. It is usually not the natural state of a healthy adult, except notably among certain eusocial species (mostly haplodiploid insects). I ...
while a lack of fecundity would be called sterility.


Demography

In demographic contexts, fertility refers to the actual production of offspring, rather than the physical capability to produce which is termed
fecundity Fecundity is defined in two ways; in human demography, it is the potential for reproduction of a recorded population Population typically refers the number of people in a single area whether it be a city or town, region, country, or the wor ...
. While fertility can be measured, fecundity cannot be. Demographers measure the fertility rate in a variety of ways, which can be broadly broken into "period" measures and "
cohort Cohort or cohortes may refer to: * Cohort (educational group), a group of students working together through the same academic curriculum * Cohort (floating point), a set of different encodings of the same numerical value * Cohort (military unit), ...
" measures. "Period" measures refer to a cross-section of the population in one year. "Cohort" data on the other hand, follows the same people over a period of decades. Both period and cohort measures are widely used.


Period measures

*
Crude birth rate The crude birth rate (CBR) in a period is the total number of live births per 1,000 population divided by the length of the period in years. The number of live births is normally taken from a universal registration system for births; population ...
(CBR) - the number of live births in a given year per 1,000 people alive at the middle of that year. One disadvantage of this indicator is that it is influenced by the age structure of the population. *General fertility rate (GFR) - the number of births in a year divided by the number of women aged 15–44, times 1000. It focuses on the potential mothers only, and takes the age distribution into account. *Child-Woman Ratio (CWR) - the ratio of the number of children under 5 to the number of women 15–49, times 1000. It is especially useful in historical data as it does not require counting births. This measure is actually a hybrid, because it involves deaths as well as births. (That is, because of
infant mortality Infant mortality is the death of young children under the age of 1. This death toll is measured by the infant mortality rate (IMR), which is the probability of deaths of children under one year of age per 1000 live births. The under-five mortali ...

infant mortality
some of the births are not included; and because of adult mortality, some of the women who gave birth are not counted either.) * Coale's Index of Fertility - a special device used in historical research


Cohort measures

*
Total fertility rate The total fertility rate (TFR) of a population is the average number of children that would be born to a woman over her lifetime if: # she was to experience the exact current age-specific fertility Fertility is the capability to produce offs ...
(TFR) - the total number of children a woman would bear during her lifetime if she were to experience the prevailing age-specific fertility rates of women. TFR equals the sum for all age groups of 5 times each ASFR rate. *Gross Reproduction Rate (GRR) - the number of girl babies a synthetic cohort will have. It assumes that all of the baby girls will grow up and live to at least age 50. *Net Reproduction Rate (NRR) - the NRR starts with the GRR and adds the realistic assumption that some of the women will die before age 49; therefore they will not be alive to bear some of the potential babies that were counted in the GRR. NRR is always lower than GRR, but in countries where mortality is very low, almost all the baby girls grow up to be potential mothers, and the NRR is practically the same as GRR. In countries with high mortality, NRR can be as low as 70% of GRR. When NRR = 1.0, each generation of 1000 baby girls grows up and gives birth to exactly 1000 girls. When NRR is less than one, each generation is smaller than the previous one. When NRR is greater than 1 each generation is larger than the one before. NRR is a measure of the long-term future potential for growth, but it usually is different from the current population growth rate.


Social and economic determinants of fertility

A parent's number of children strongly correlates with the number of children that each person in the next generation will eventually have. Factors generally associated with increased fertility include
religiosity The concept of religiosity has proven difficult to define. The Oxford English Dictionary suggests: "Religiousness; religious feeling or belief. ..Affected or excessive religiousness". Different scholars have seen this concept as broadly about ...
, intention to have children, and maternal support. Factors generally associated with decreased fertility include
wealth Wealth is the abundance of valuable financial asset A financial asset is a non-physical asset whose value is derived from a contractual claim, such as deposit (finance), bank deposits, bond (finance), bonds, and participations in companies' sh ...
, education,
female labor participation Since the industrial revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe Continental Europe or mainland Europe is the contiguous continent A contin ...
,
urban Urban means "related to a city". In that sense, the term may refer to: * Urban area, geographical area distinct from rural areas * Urban culture, the culture of towns and cities. Urban may also refer to: General * Urban (name), a list of people ...
residence, cost of housing,
intelligence Intelligence has been defined in many ways: the capacity for abstraction, logic, understanding, self-awareness, learning, emotional knowledge, reasoning, planning, creativity, critical thinking, and problem-solving. More generally, it can be des ...
,
increased female age
increased female age
and (to a lesser degree) increased male age. The "Three-step Analysis" of the fertility process was introduced by Kingsley Davis and Judith Blake in 1956 and makes use of three proximate determinants: The economic analysis of fertility is part of
household economicsHousehold economics analyses all the decisions made by household. These analyses are both at the microeconomic and macroeconomic level. This field analyse the structures of the household and their behaviour: it includes decision making, division of l ...
, a field that has grown out of the
New Home Economics Gary Stanley Becker (; December 2, 1930 – May 3, 2014) was an American economist who received the 1992 Nobel Memorial Prize in Economic Sciences The Nobel Memorial Prize in Economic Sciences, officially the Sveriges Riksbank Prize in Economic ...
. Influential economic analyses of fertility include Becker (1960), Mincer (1963), and Easterlin (1969). The latter developed the
Easterlin hypothesisThe Easterlin hypothesis (Easterlin 1961, 1969, 1973) states that the positive relationship between income and fertility is dependent on relative income. It is considered the first viable and a still leading explanation for Mid-20th century baby boom ...
to account for the Baby Boom.


Bongaarts' model of components of fertility

Bongaarts proposed a model where the total fertility rate of a population can be calculated from four proximate determinants and the total fecundity (TF). The index of marriage (Cm), the index of contraception (Cc), the index of induced abortion (Ca) and the index of postpartum infecundability (Ci). These indices range from 0 to 1. The higher the index, the higher it will make the TFR, for example a population where there are no induced abortions would have a Ca of 1, but a country where everybody used infallible contraception would have a Cc of 0. TFR = TF × Cm × Ci × Ca × Cc These four indices can also be used to calculate the total marital fertility (TMFR) and the total natural fertility (TN). TFR = TMFR × Cm TMFR = TN × Cc × Ca TN = TF × Ci ;Intercourse :The first step is
sexual intercourse Sexual intercourse (or coitus or copulation) is a sexual activity Human sexual activity, human sexual practice or human sexual behaviour is the manner in which humans experience and express their sexuality Human sexuality is the w ...

sexual intercourse
, and an examination of the average age at first intercourse, the average frequency outside marriage, and the average frequency inside. ;
Conception
Conception
:Certain physical conditions may make it impossible for a woman to conceive. This is called "involuntary infecundity." If the woman has a condition making it possible, but unlikely to conceive, this is termed "subfecundity."
Venereal diseases Sexually transmitted infections (STIs), also referred to as sexually transmitted diseases (STDs), are infection An infection is the invasion of an organism's body Tissue (biology), tissues by Pathogen, disease-causing agents, their multipl ...
(especially
gonorrhea Gonorrhea, colloquially known as the clap, is a sexually transmitted infection (STI) caused by the bacterium ''Neisseria gonorrhoeae''. Infection may involve the genitals, mouth, or rectum. Infected men may experience Dysuria, pain or burning ...
,
syphilis Syphilis is a sexually transmitted infection Sexually transmitted infections (STIs), also referred to as sexually transmitted diseases (STDs) and the older term venereal disease, are infection An infection is the invasion of an orga ...
, and
chlamydia Chlamydia, or more specifically a chlamydia infection, is a sexually transmitted infection caused by the bacterium '' Chlamydia trachomatis''. Most people who are infected have no symptoms. When symptoms do appear it can be several weeks after ...
) are common causes.
Nutrition Nutrition is the biochemical and physiological process by which an organism uses food to support its life. It includes ingestion, Absorption (biology), absorption, Assimilation (biology), assimilation, biosynthesis, catabolism and excretion. ...
is a factor as well: women with less than 20% body fat may be subfecund, a factor of concern for
athletes An athlete (also sportsman or sportswoman) is a person who competes in one or more sport Sport pertains to any form of competitive Competition is a rivalry A rivalry is the state of two people or groups engaging in a lasting com ...
and people susceptible to
anorexia Anorexia nervosa, often referred to simply as anorexia, is an eating disorder, characterized by underweight, low weight, Calorie restriction, food restriction, fear of gaining weight and a strong desire to be thin. Many people with anorexia see ...
. Demographer Ruth Frisch has argued that "It takes 50,000 calories to make a baby". There is also subfecundity in the weeks following childbirth, and this can be prolonged for a year or more through
breastfeeding Breastfeeding, also called nursing, is the process of feeding a mother's breast milk to her infant, either directly from the breast or by expressing (pumping out) the milk from the breast and bottle-feeding it to the infant. The World Healt ...

breastfeeding
. A furious political debate raged in the 1980s over the ethics of baby food companies marketing infant formula in developing countries. A large industry has developed to deal with subfecundity in women and men. An equally large industry has emerged to provide
contraceptive Birth control, also known as contraception, anticonception, and fertility control, is a method or device used to prevent pregnancy Pregnancy, also known as gestation, is the time during which one or more offspring develops inside a woman ...
devices designed to prevent conception. Their effectiveness in use varies. On average, 85% of married couples using no contraception will have a pregnancy in one year. The rate drops to the 20% range when using withdrawal, vaginal sponges, or spermicides. (This assumes the partners never forget to use the contraceptive.) The rate drops to only 2 or 3% when using
the pill The combined oral contraceptive pill (COCP), often referred to as the birth control pill or colloquially as "the pill", is a type of birth control Birth control, also known as contraception, anticonception, and fertility control, is a meth ...
or an
IUD
IUD
, and drops to near 0% for implants and 0% for
tubal ligation Tubal ligation (commonly known as having one's "tubes tied") is a surgical procedure for female sterilization in which the fallopian tube The Fallopian tubes, also known as uterine tubes, salpinges (singular salpinx), or oviducts, are tubes that ...
( sterilization) of the woman, or a
vasectomy Vasectomy is a surgical procedure for male Sterilization (medicine), sterilization or permanent contraception. During the procedure, the male vas deferens, vasa deferentia are cut and tied or sealed so as to prevent sperm from entering into the ure ...

vasectomy
for the man. ;
Gestation Gestation is the period of development Development or developing may refer to: Arts *Development hell, when a project is stuck in development *Filmmaking#Development, Filmmaking, development phase, including finance and budgeting *Development ...
:After a
fetus A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo An embryo is the early stage of development of a multicellular organism A multicellular organism is an organism tha ...

fetus
is conceived, it may or may not survive to birth. "Involuntary fetal mortality" involves natural abortion,
miscarriage Miscarriage, also known in medical terms as a spontaneous abortion and pregnancy loss, is the natural loss of an embryo An embryo is the early stage of development of a multicellular organism A multicellular organism is an organism ...
s and
stillbirth Stillbirth is typically defined as fetal A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo An embryo is the early stage of development of a multicellular organism ...
(a fetus born dead). Human intervention intentionally causing abortion of the fetus is called "
therapeutic abortion Abortion is the ending of a pregnancy by removal or expulsion of an embryo or fetus. An abortion that occurs without intervention is known as a miscarriage or "spontaneous abortion" and occurs in approximately 30% to 40% of pregnancies. ...
".


Fertility biology

Women have
hormonal A hormone (from the Greek participle , "setting in motion") is any member of a class of signaling molecules in multicellular organisms, that are transported to distant organs to regulate physiology and / or behavior. Hormones are required for ...
cycles which determine when they can achieve
pregnancy Pregnancy, also known as gestation, is the time during which one or more offspring In biology, offspring are the young creation of living organisms, produced either by a Asexual reproduction, single organism or, in the case of sexual repr ...

pregnancy
. The cycle is approximately twenty-eight days long, with a fertile period of five days per cycle, but can deviate greatly from this norm. Men are fertile continuously, but their
sperm quality Semen quality is a measure of male fertility, a measure of the ability of sperm in semen to accomplish fertilization. Semen quality involves both sperm quantity and quality Cryptorchidism, hypospadias, testicular cancer and poor semen quality ma ...
is affected by their health, frequency of ejaculation, and environmental factors. Fertility declines with age in both sexes. For women, the decline begins around the age of 32, and becomes precipitous at age 37. For men, potency begins to decline around the age of 40. Even if an older couple does manage to conceive a child, the pregnancy will be increasingly difficult for the mother, and carries a higher risk of
birth defect A birth defect, also known as a congenital disorder, is a condition present at birth Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is initiat ...
s and
genetic disorder A genetic disorder is a health problem caused by one or more abnormalities in the genome In the fields of molecular biology Molecular biology is the branch of biology Biology is the natural science that studies life and li ...
s for the child. Pregnancy rates for sexual intercourse are highest when it occurs every 1 or 2 days, or every 2 or 3 days. Studies have found no significant difference between different sex positions and pregnancy rate, as long as it results in
ejaculation Ejaculation is the discharge of semen Semen, also known as seminal fluid, is an organic fluid created to contain spermatozoon, spermatozoa. It is secreted by the gonads (sexual glands) and other sexual organs of male or hermaphrodite, her ...

ejaculation
into the
vagina In mammal Mammals (from Latin language, Latin , 'breast') are a group of vertebrate animals constituting the class (biology), class Mammalia (), and characterized by the presence of mammary glands which in Female#Mammalian female, femal ...

vagina
.


Menstrual cycle

A woman's menstrual cycle begins, as arbitrarily assigned, with menses. Next is the follicular phase where estrogen levels build as an ovum matures (due to the follicular stimulating hormone, or FSH) within the ovary. When estrogen levels peak, it spurs a surge of luteinizing hormone (LH) which completes maturation and enables the ovum to break through the ovary wall. This is ovulation. During the luteal phase following ovulation LH and FSH cause the post-ovulation ovary to develop into the corpus luteum which produces progesterone. The production of progesterone inhibits the LH and FSH hormones which (in a cycle without pregnancy) causes the corpus luteum to atrophy, and menses to begin the cycle again. Peak fertility occurs during just a few days of the cycle: usually two days before and two days after the ovulation date. This fertile window varies from woman to woman, just as the ovulation date often varies from cycle to cycle for the same woman. The
ovule In seed plant A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The band's first double album, it was released ...

ovule
is usually capable of being fertilized for up to 48 hours after it is released from the
ovary The ovary is an organ found in the female reproductive system The female reproductive system is made up of the internal and external sex organs that function in reproduction of new offspring. In humans, the female reproductive system is im ...

ovary
.
Sperm Sperm is the male reproductive Cell (biology), cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as ...

Sperm
survive inside the
uterus The uterus (from Latin "uterus", plural ''uteri'') or womb () is the main female hormone-responsive, sex organ, secondary sex organ of the reproductive system in humans and most other mammals. Things occurring in the uterus are described with t ...

uterus
between 48 and 72 hours on average, with the maximum being 120 hours (5 days). These periods and intervals are important factors for couples using the
rhythm method Calendar-based methods are various methods of estimating a woman A woman is an adult female Female (symbol: ♀) is the sex of an organism, or a part of an organism, that produces non-mobile ovum, ova (egg cells). Barring rare medical cond ...
of contraception.


Female fertility

The average age of
menarche Menarche ( ; ) is the first menstrual cycle, or first Menstruation, menstrual bleeding, in female humans. From both social and medical perspectives, it is often considered the central event of female puberty, as it signals the possibility of fe ...
in the United States is about 12.5 years. In postmenarchal girls, about 80% of the cycles are
anovulatory Anovulation is when the ovaries do not release an oocyte An oocyte (, ), oöcyte, ovocyte, or rarely ocyte, is a female gametocyte A gametocyte is a eukaryotic Eukaryotes () are organism In biology, an organism (from Ancient Greek, ...
(ovulation does not actually take place) in the first year after menarche, 50% in the third and 10% in the sixth year.
Menopause Menopause, also known as the climacteric, is the time in women's lives when menstrual periods stop permanently, and they are no longer able to bear children. Menopause usually occurs between the age of 48 and 52. Medical professionals often ...
occurs during a woman's midlife between ages 48 and 55. During menopause, hormonal production by the ovaries is reduced, eventually causing a permanent cessation of the creation of the uterine lining (period). This is considered the end of the fertile phase of a woman's life. The predicted effect of
age on female fertility
age on female fertility
in women trying to get pregnant, without using fertility drugs or in vitro fertilization:A computer simulation run by Henri Leridon, PhD, an epidemiologist with the French Institute of Health and Medical Research: * *At age 30 **75% will conceive ending in a live birth within one year **91% will conceive ending in a live birth within four years. *At age 35 ** 66% will conceive ending in a live birth within one year ** 84% will conceive ending in a live birth within four years. *At age 40 **44% will conceive ending in a live birth within one year **64% will conceive ending in a live birth within four years. Studies of couples trying to conceive have yielded better results: one 2004 study of 770 European women found that 82% of 35- to 39-year-old women conceived within a year, while a study in 2013 of 2,820 Danish women saw 78% of 35- to 40-year-olds conceive within a year. According to an opinion by the Practice Committee of the American Society for Reproductive Medicine, specific coital timing or position, and resting supine after intercourse have no significant impact on fertility. Sperm can be found in the cervical canal seconds after ejaculation, regardless of coital position. The use of fertility drugs and/or invitro fertilization can increase the chances of becoming pregnant at a later age. Successful pregnancies facilitated by fertility treatment have been documented in women as old as 67. Studies since 2004 have shown that mammals may continue to produce new eggs throughout their lives, rather than being born with a finite number as previously thought. Researchers at the
Massachusetts General Hospital Massachusetts General Hospital (Mass General or MGH) is the original and largest teaching hospital A teaching hospital is a hospital A hospital is a institution providing treatment with specialized and staff and medical equipment. Th ...
in Boston say that if eggs are newly created each month in humans, current theories about the aging of the female reproductive system will have to be overhauled, although this is
conjecture In mathematics Mathematics (from Greek: ) includes the study of such topics as numbers (arithmetic and number theory), formulas and related structures (algebra), shapes and spaces in which they are contained (geometry), and quantities and ...
. According to the
March of Dimes March of Dimes is a United States nonprofit organization A nonprofit organization (NPO), also known as a non-business entity, not-for-profit organization, or nonprofit institution, is a legal entity organized and operated for a collective, ...
, "about 9 percent of recognized pregnancies for women aged 20 to 24 ended in miscarriage. The risk rose to about 20 percent at age 35 to 39, and more than 50 percent by age 42". Birth defects, especially those involving
chromosome A chromosome is a long DNA molecule with part or all of the genome, genetic material of an organism. Most eukaryotic chromosomes include packaging proteins called histones which, aided by Chaperone (protein), chaperone proteins, bind to and ...

chromosome
number and arrangement, also increase with the age of the mother. The March of Dimes reports "At age 25, your risk of having a baby with
Down syndrome Down syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder A genetic disorder is a health problem caused by one or more abnormalities in the genome In the fields of molecular biology and genetics Gen ...
is 1 in 1,340. At age 30, your risk is 1 in 940. At age 35, your risk is 1 in 353. At age 40, your risk is 1 in 85. At age 45, your risk is 1 in 35."


Male fertility

Some research suggests that older males have decreased semen volume,
sperm motility Sperm motility describes the ability of sperm Sperm is the male reproductive Cell (biology), cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, "female" reproductive cell and a smaller, "male" one). ...
, and impaired sperm morphology. In studies that controlled for female age, comparisons between men under 30 and men over 50 found relative decreases in
pregnancy ratePregnancy rate is the success rate for getting pregnant. It is the percentage of all attempts that leads to pregnancy, with attempts generally referring to menstrual cycles where insemination Insemination is the introduction of sperm Sperm is t ...
s between 23% and 38%.
Sperm count Sperm is the male reproductive cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Closed spaces * Monastic cell, a small room, hut, or cave in which a monk or religious recluse lives ...
declines with age, with men aged 50–80 years producing sperm at an average rate of 75% compared with men aged 20–50 years and larger differences exist in the number of
seminiferous tubules Seminiferous tubules are located within the testes Testicle or testis (plural testes) is the male reproductive gland or gonad A gonad, sex gland, or reproductive gland is a mixed gland that produces the gametes (sex cells) and sex hormon ...
in the
testes Testicle or testis (plural testes) is the male Male (symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilization. A male or ...

testes
containing mature sperm: *In males 20–39 years old, 90% of the seminiferous tubules contain mature sperm. *In males 40–69 years old, 50% of the seminiferous tubules contain mature sperm. *In males 80 years old and older, 10% of the seminiferous tubules contain mature sperm. Decline in male fertility is influenced by many factors, including lifestyle, environment and psychological factors. Some research suggests increased risks for health problems for children of older fathers, but no clear association has been proven. A large scale in
Israel Israel (; he, יִשְׂרָאֵל, translit=Yīsrāʾēl; ar, إِسْرَائِيل, translit=ʾIsrāʾīl), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a ...

Israel
study suggested that the children of men 40 or older were 5.75 times more likely than children of men under 30 to have an
autism spectrum disorder The autism spectrum encompasses a range of neurodevelopmental conditions, including autism Autism is a developmental disorder Developmental disorders comprise a group of psychiatric conditions originating in childhood that involve ...
, controlling for year of birth, socioeconomic status, and maternal age. Increased paternal age has been suggested to correlate with
schizophrenia Schizophrenia is a mental disorder A mental disorder, also called a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may b ...

schizophrenia
but it is unproven. Australian researchers have found evidence to suggest
obesity Obesity is a medical condition A disease is a particular abnormal condition that negatively affects the structure or function (biology), function of all or part of an organism, and that is not due to any immediate external injury. ...
may cause subtle damage to sperm and prevent a healthy pregnancy. They reported fertilization was 40% less successful when the father was overweight. The American Fertility Society recommends an age limit for sperm donors of 50 years or less, and many
fertility clinic Fertility clinics are medical clinics that assist couples, and sometimes individuals, who want to become parents but for medical reasons have been unable to achieve this goal via the natural course. Clinics apply a number of diagnosis tests and s ...
s in the
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain,Usage is mixed. The Guardian' and Telegraph' use Britain as a synonym for the United Kingdom. Some prefer to use Britain as shorth ...

United Kingdom
will not accept donations from men over 40 or 45 years of age.Age Limit of Sperm Donors in the United Kingdom
Pdf file


Historical trends by country


France

The pronatalist movement from 1919 to 1945 failed to convince French couples they had a patriotism, patriotic duty to help increase their country's birthrate. Even the government was reluctant in its support to the movement. It was only between 1938 and 1939 that the French government became directly and permanently involved in the pronatalist effort. Although the birthrate started to surge in late 1941, the trend was not sustained. Falling birthrate once again became a major concern among demographers and government officials beginning in the 1970s. In mid-2018, there was a bill introduced to legalize single women and lesbian couples to get fertility treatment. At the beginning of 2020, the Senate approved the bill 160 votes to 116. They are a step closer to legalizing fertility treatments for all women regardless of sexual orientation or marital status. Soon there will be no reason for lesbian couples or single women to travel to be able to start their own family.


United States

From 1800 to 1940, fertility fell in the US. There was a marked decline in fertility in the early 1900s, associated with improved contraceptives, birth control movement in the United States, greater access to contraceptives and sexuality information and the "first" sexual revolution in the 1920s.


Post-WWII

After 1940 fertility suddenly started going up again, reaching a new peak in 1957. After 1960, fertility started declining rapidly. In the Baby Boom years (1946–1964), women married earlier and had their babies sooner; the number of children born to mothers after age 35 did not increase.


Sexual revolution

After 1960, new methods of contraception became available, ideal family size fell, from 3 to 2 children. Couples postponed marriage and first births, and they sharply reduced the number of third and fourth births.


Infertility

Infertility primarily refers to the biological inability of a person to contribute to fertilization, conception. Infertility may also refer to the state of a woman who is unable to carry a pregnancy to full term. There are many biological causes of infertility, including some that medical intervention can treat.


See also

* Birth control * Family economics * Family planning * Fecundity * Fertility clinic * Fertility tourism * Fertility deity * Fertility equality * Fertility preservation * Human Fertilisation and Embryology Authority * Natural fertility * Oncofertility * Reproductive health * Sub-replacement fertility *
Total fertility rate The total fertility rate (TFR) of a population is the average number of children that would be born to a woman over her lifetime if: # she was to experience the exact current age-specific fertility Fertility is the capability to produce offs ...
* Vasectomy * Fertility-development controversy * Fertility factor (demography) ** Income and fertility ** Fertility and intelligence


Footnotes


References

* Barrett, Richard E., Donald J. Bogue, and Douglas L. Anderton. ''The Population of the United States'' 3rd Edition (1997) compendium of data * * Ansley J. Coale, Coale, Ansley J. and Susan C. Watkins, eds. ''The Decline of Fertility in Europe,'' (1986) * Eversley, D. E. C. ''Social Theories of Fertility and the Malthusian Debate'' (1959
online edition
* Garrett, Eilidh et al. ''Family Size in England and Wales: Place, Class, and Demography, 1891-1911''(2001
online edition
* Grabill, Wilson H.. Clyde V. Kiser, Pascal K. Whelpton. ''The Fertility of American Women'' (1958), influential study at the peak of the Baby Boo
online edition
* GuzmÁn, JosÉ Miguel et al. ''The Fertility Transition in Latin America'' (1996
online edition
* Haines, Michael R. and Richard H. Steckel (eds.), ''A Population History of North America.'' Cambridge University Press, 2000, 752 pp. advanced scholarship * Hawes, Joseph M. and Elizabeth I. Nybakken, eds. ''American Families: a Research Guide and Historical Handbook.'' (Greenwood Press, 1991) * Klein, Herbert S. ''A Population History of the United States.'' Cambridge University Press, 2004. 316 pp * Knox, P. L. et al. ''The United States: A Contemporary Human Geography.'' Longman, 1988. 287 pp. * Kohler, Hans-Peter ''Fertility and Social Interaction: An Economic Perspective'' (2001
online edition
* Leete, Richard. ''Dynamics of Values in Fertility Change'' (1999
online edition
* Lovett, Laura L. ''Conceiving the Future: Pronatalism, Reproduction, and the Family in the United States, 1890–1938,'' (2007) 236 pages; * Mintz Steven and Susan Kellogg. ''Domestic Revolutions: a Social History of American Family Life.'' (1988) * * Population Reference Bureau, ''Population Handbook'' (5th ed. 2004)
online
(5th ed. 2004). * Reed, James. ''From Private Vice to Public Virtue: The Birth Control Movement and American Society Since 1830.'' 1978. * Tarver, James D. ''The Demography of Africa'' (1996
online edition
* Weeks, John R. ''Population: An Introduction to Concepts and Issues'' (10th ed. 2007), standard textbook


Journals

* ''Demography''
Scope and links to issue contents & abstracts.
* ''Journal of Population Economics'' * ''Population and Development Review'' —
Aims and abstract & supplement links.
* ''Population Bulletin'' — Each issue on a
current population topic.
* ''Population Studies''
Aims and scope.
* ''Review of Economics of the Household''


Further reading

* Josef Ehmer, Jens Ehrhardt, Martin Kohli (Eds.)
''Fertility in the History of the 20th Century: Trends, Theories, Policies, Discourses''
Historical Social Research 36 (2), 2011.
Fertility treatment and clinics in the UK - HFEA
* Jorge Chavarro (2009) ''The Fertility Diet: Groundbreaking Research Reveals Natural Ways to Boost Ovulation and Improve Your Chances of Getting Pregnant,'' McGraw-Hill Professional. * *
Fertility statistics from the Commission on Population Growth and the American Future (1972)


External links



Data on fertility trends worldwide {{Authority control Fertility,