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Human reproduction

May 02, 2023

Human reproduction is sexual reproduction that results in human fertilization to produce a human offspring. It typically involves sexual intercourse between a sexually mature human male and female.[1] During sexual intercourse, the interaction between the male and female reproductive systems results in fertilization of the ovum by the sperm to form a zygote.[1] These specialized reproductive cells are called gametes, which are created in a process called gametogenesis.[2] While normal cells contain 46 chromosomes (23 pairs), gamete cells only contain 23 single chromosomes, and it is when these two cells merge into one zygote cell that genetic recombination occurs and the new zygote contains 23 chromosomes from each parent, giving it 46 chromosomes (23 pairs).[2] The zygote then undergoes a defined development process that is known as human embryogenesis, and this starts the typical 9-month gestation period that is followed by childbirth.[1][3] The fertilization of the ovum may be achieved by artificial insemination methods, which do not involve sexual intercourse.[4] Assisted reproductive technology also exists.

Biological and legal requirements

In order for human reproduction to be achieved, an individual must have undergone puberty first, requiring ovulation in females and the spermarche in males to have occurred prior to engaging in sexual intercourse or achieving pregnancy through non-penetrative means. Before puberty, humans are infertile, as their genitals lack reproductive function (only being able to discharge urine).

Legal factors also play a vital role in the achievement of human reproduction: a minor under the age of consent cannot give legal consent to sexual intercourse or artificial alternatives to reproduction, the former case of which is liable to have the older party charged with statutory rape, depending on jurisdictions.[5][6] Even for minors above the age of consent, comprehensive sex education advises both consenting parties to use contraception to avoid both sexually transmitted diseases and early, unplanned/unwanted pregnancies. Pregnancy in girls under the age of 15 is especially discouraged due to their reproductive systems having yet to reach full maturity.[7]

Anatomy

Further information: Human reproductive system

Male reproductive system

Further information: Male reproductive system

The male reproductive system contains two main divisions: the testes where sperm are produced, and the penis which discharges the sperm as semen (this is known as an ejaculation). In humans, both of these organs are outside the abdominal cavity. Having the testes outside the abdomen facilitates temperature regulation of the sperm, which require specific temperatures to survive about 2-3 °C less than the normal body temperature i.e. 37 °C. In particular, the extraperitoneal location of the testes may result in a 2-fold reduction in the heat-induced contribution to the spontaneous mutation rate in male germinal tissues compared to tissues at 37 °C.[8] If the testicles remain too close to the body, it is likely that the increase in temperature will harm the spermatozoa formation, making conception more difficult. This is why the testes are carried in an external scrotum rather than within the abdomen; they normally remain slightly cooler than body temperature, facilitating sperm production.

Female reproductive system

Further information: Female reproductive system

The female reproductive system likewise contains two main divisions: the external genitalia and the internal genitalia.

The ovum meets with the sperm cell: a sperm may penetrate and merge with the egg, fertilizing it with the help of certain hydrolytic enzymes present in the acrosome. The fertilization usually occurs in the oviducts, but can happen in the uterus itself. The zygote then becomes implanted in the lining of the uterus, where it begins the processes of embryogenesis and morphogenesis. When the fetus is developed enough to survive outside of the uterus, the cervix dilates and contractions of the uterus propel it through the birth canal, which is the vagina, and thereby gives external life to the newborn infant. This process is called childbirth.

The ova, which are the female sex cells, are much larger than the spermatozoon and are normally formed within the ovaries of the female fetus before birth. They are mostly fixed in location within the ovary until their transit to the uterus, and contain nutrients for the later zygote and embryo. Over a regular interval known as the menstrual cycle, in response to hormonal signals, a process of oogenesis matures one ovum which is released and sent down the Fallopian tube. If not fertilized, this egg is flushed out of the system through menstruation.

Process of fertilization

 
"Coition of a Hemisected Man and Woman" (c. 1492) by Leonardo da Vinci.

Human reproduction normally begins with copulation, though it may be achieved through artificial insemination, and is followed by nine months of pregnancy before childbirth. Pregnancy can be avoided with the use of contraceptives such as condoms and intrauterine devices.[9]

Copulation

Main article: Sexual intercourse

Human reproduction naturally takes place as internal fertilization by sexual intercourse. During this process, the man inserts his erect penis into the woman's vagina and then either partner initiates rhythmic pelvic thrusts until the man achieves orgasm, which leads to ejaculation of semen containing sperm into the vaginal canal. The sperm and the ovum are known as the gametes (each containing half the genetic information of the parent, created through meiosis).[2] The sperm (being one of approximately 250 million sperm in a typical ejaculation) travels through the vagina and cervix into the uterus or Fallopian tubes. Only 1 in 14 million of the ejaculated sperm will reach the Fallopian tube. The egg simultaneously moves through the Fallopian tube away from the ovary. One of the sperm encounters, penetrates and fertilizes the ovum, creating a zygote. Upon fertilization and implantation, gestation of the fetus then occurs within the uterus.[10][11][12][13]

 
Chance of fertilization by menstrual cycle day relative to ovulation.[14]

Pregnancy rates for sexual intercourse are highest during the menstrual cycle time from some 5 days before until 1 to 2 days after ovulation.[15] For optimal pregnancy chance, there are recommendations of sexual intercourse every 1 or 2 days,[16] or every 2 or 3 days.[17] Studies have shown no significant difference between different sex positions and pregnancy rate, as long as it results in ejaculation into the vagina.[18]

Alternative methods

As an alternative to natural sexual intercourse, there exists artificial insemination, where sperm is introduced into the female reproductive system without the insertion of the penis.[4] There are also many methods of assisted reproductive technology, such as in vitro fertilization, where one or more egg cells are retrieved from a woman's ovaries and co-incubated with sperm outside the body. The resulting embryo can then be reinserted into the womb of the woman.[citation needed]

Pregnancy

Main article: Pregnancy

Pregnancy is the period of time during which the fetus develops, dividing via mitosis inside the uterus. During this time, the fetus receives all of its nutrition and oxygenated blood from the mother, filtered through the placenta, which is attached to the fetus' abdomen via an umbilical cord. This drain of nutrients can be quite taxing on the mother, who is required to ingest slightly higher levels of calories. In addition, certain vitamins and other nutrients are required in greater quantities than normal, often creating abnormal eating habits. Gestation period is about 266 days in humans. While in the uterus, the baby first endures a very brief zygote stage, then the embryonic stage, which is marked by the development of major organs and lasts for approximately eight weeks, then the fetal stage, which revolves around the development of bone cells while the fetus continues to grow in size.[19] It is estimated that about 3-5% of couples are infertile and the fecunditity of couples is around 30% for each menstrual cycle.[20]

Labor and birth

 
Newborn infant and mother
Main article: Childbirth

Labor is separated into 4 stages. The first stage involves latent phase and active phase separated by the dilation of the cervix for 6 to 10 cm. The second stage is the pushing stage. The third stage involves the delivery of the placenta. And the last stage is the contraction of the uterus.[21] Once the fetus is sufficiently developed, chemical signals begin the process of birth, which begins with the fetus being pushed out of the birthing canal. The newborn, which is called an infant in humans, should typically begin respiration on its own shortly after birth. Not long after, the placenta eventually falls off on its own. The person assisting the birth may also sever the umbilical cord.

Discovery of mechanism

While most ancient human societies believed that sexual intercourse was necessary for reproduction, the reasons some sex did not result in children, and the mechanism by which mating produced children were not understood. The theory of preformationism was popular in Ancient Greece and Christendom for centuries. Because they are too small to see with the naked eye, it was only after his invention of the microscope that Antonie van Leeuwenhoek discovered spermatozoa in 1677. Mitosis and meiosis were not discovered until the late 1800s.

See also

References

  1. ^ a b c Jones, Richard E. (1991), "The Male Reproductive System", Human Reproductive Biology, Elsevier, pp. 72–93, doi:10.1016/b978-0-12-389770-1.50008-1, ISBN 9780123897701, from the original on 2022-09-12, retrieved 2022-09-12
  2. ^ a b c "Gametogenesis - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2022-09-12.
  3. ^ "Embryogenesis - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2022-09-13.
  4. ^ a b Ombelet, W.; Van Robays, J. (2015). "Artificial insemination history: hurdles and milestones". Facts, Views & Vision in ObGyn. 7 (2): 137–143. ISSN 2032-0418. PMC 4498171. PMID 26175891.
  5. ^ Carmen M. Cusack (2015). Laws Relating to Sex, Pregnancy, and Infancy: Issues in Criminal Justice. Springer. p. 10. ISBN 978-1137505194. from the original on May 9, 2021. Retrieved August 31, 2021. Voluntary sexual intercourse with a post-pubescent minor who is younger than the legal age of consent is described as statutory rape. [...] In most states, age of consent is delimited between 16 years old and 18 years old. [...] In almost every jurisdiction, prepubescent children may not engage in any sexual contact. [...] Engaging in sexual contact with a prepubescent child is a serious criminal offense and a felony.
  6. ^ "Statutory Rape Known to Law Enforcement" (PDF). U.S. Department of Justice - Office of Juvenile Justice and Delinquency Prevention. (PDF) from the original on 2007-10-21. Retrieved 2021-08-31.
  7. ^ Mayor S (2004). "Pregnancy and childbirth are leading causes of death in teenage girls in developing countries". BMJ. 328 (7449): 1152. doi:10.1136/bmj.328.7449.1152-a. PMC 411126. PMID 15142897.
  8. ^ Baltz RH, Bingham PM, Drake JW (1976). "Heat mutagenesis in bacteriophage T4: The transition pathway". Proc. Natl. Acad. Sci. USA. 73 (4): 1269–1273. Bibcode:1976PNAS...73.1269B. doi:10.1073/pnas.73.4.1269. PMC 430244. PMID 4797.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  9. ^ Teal, Stephanie; Edelman, Alison (2021-12-28). "Contraception Selection, Effectiveness, and Adverse Effects: A Review". JAMA. 326 (24): 2507–2518. doi:10.1001/jama.2021.21392. ISSN 0098-7484. PMID 34962522. S2CID 245557522. from the original on 2022-08-26. Retrieved 2022-09-12.
  10. ^ Ghazal, S, Kulp Makarov, J; et al. (2014). "Egg Transport and Fertilization". The Global Library of Women's Medicine. doi:10.3843/GLOWM.10317. ISSN 1756-2228. from the original on May 13, 2016. Retrieved May 8, 2016.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. ^ "Conception: How It Works". The Regents of The University of California. 2002. from the original on March 15, 2016. Retrieved May 8, 2016.
  12. ^ "Fertility Basics". Complete Fertility Centre Southampton. Complete Fertility Ltd. 2015. from the original on May 8, 2016. Retrieved May 8, 2016.
  13. ^ "Conception & Pregnancy: Ovulation, Fertilization, and More". WebMD, LLC. 2016. from the original on May 8, 2016. Retrieved May 8, 2016.
  14. ^ Dunson, D.B.; Baird, D.D.; Wilcox, A.J.; Weinberg, C.R. (1999). "Day-specific probabilities of clinical pregnancy based on two studies with imperfect measures of ovulation". Human Reproduction. 14 (7): 1835–1839. doi:10.1093/humrep/14.7.1835. ISSN 1460-2350. PMID 10402400.
  15. ^ Pages.242,374 in: Weschler, Toni (2002). Taking Charge of Your Fertility (Revised ed.). New York: HarperCollins. pp. 359–361. ISBN 0-06-093764-5.
  16. ^ "How to get pregnant". Mayo Clinic. 2016-11-02. from the original on 2020-05-18. Retrieved 2018-02-16.
  17. ^ "Fertility problems: assessment and treatment, Clinical guideline [CG156]". National Institute for Health and Care Excellence. from the original on 2018-02-17. Retrieved 2018-02-16. Published date: February 2013. Last updated: September 2017
  18. ^ Dr. Philip B. Imler & David Wilbanks. (PDF). American Pregnancy Association. Archived from the original (PDF) on 2018-06-01. Retrieved 2018-02-16.
  19. ^ Feist, Gregory J.; Rosenberg, Erika L. (11 October 2011). Psychology: Perspectives and Connections (Second ed.). McGraw Hill. pp. (171–172). ISBN 978-0-07-803520-3.
  20. ^ Spira, A. (February 1986). "Epidemiology of human reproduction". Human Reproduction (Oxford, England). 1 (2): 111–115. doi:10.1093/oxfordjournals.humrep.a136353. ISSN 0268-1161. PMID 3549765. from the original on 2022-06-15. Retrieved 2022-09-12.
  21. ^ Liao, John B.; Buhimschi, Catalin S.; Norwitz, Errol R. (June 2005). "Normal labor: mechanism and duration". Obstetrics and Gynecology Clinics of North America. 32 (2): 145–164, vii. doi:10.1016/j.ogc.2005.01.001. ISSN 0889-8545. PMID 15899352. from the original on 2022-06-15. Retrieved 2022-09-12.

Altrui - The Human Egg Cell Explained

Further reading

  • Hopwood, Nick, Rebecca Flemming, Lauren Kassell, eds. Reproduction: Antiquity to the Present Day (Cambridge UP, 2018). Illustrations. xxxv + 730 pp. ISBN 978-1-107-06802-5 excerpt also online review 44 scholarly essays by historians.
  • Dolnick, Edward (2017). The Seeds of Life: From Aristotle to da Vinci, from Sharks' Teeth to Frogs' Pants, the Long and Strange Quest to Discover Where Babies Come. Basic Books. ISBN 978-0465082957.

May 02, 2023
human, reproduction, sexual, reproduction, that, results, human, fertilization, produce, human, offspring, typically, involves, sexual, intercourse, between, sexually, mature, human, male, female, during, sexual, intercourse, interaction, between, male, female. Human reproduction is sexual reproduction that results in human fertilization to produce a human offspring It typically involves sexual intercourse between a sexually mature human male and female 1 During sexual intercourse the interaction between the male and female reproductive systems results in fertilization of the ovum by the sperm to form a zygote 1 These specialized reproductive cells are called gametes which are created in a process called gametogenesis 2 While normal cells contain 46 chromosomes 23 pairs gamete cells only contain 23 single chromosomes and it is when these two cells merge into one zygote cell that genetic recombination occurs and the new zygote contains 23 chromosomes from each parent giving it 46 chromosomes 23 pairs 2 The zygote then undergoes a defined development process that is known as human embryogenesis and this starts the typical 9 month gestation period that is followed by childbirth 1 3 The fertilization of the ovum may be achieved by artificial insemination methods which do not involve sexual intercourse 4 Assisted reproductive technology also exists Contents 1 Biological and legal requirements 2 Anatomy 2 1 Male reproductive system 2 2 Female reproductive system 3 Process of fertilization 3 1 Copulation 3 2 Alternative methods 3 3 Pregnancy 3 4 Labor and birth 4 Discovery of mechanism 5 See also 6 References 7 Further readingBiological and legal requirements EditIn order for human reproduction to be achieved an individual must have undergone puberty first requiring ovulation in females and the spermarche in males to have occurred prior to engaging in sexual intercourse or achieving pregnancy through non penetrative means Before puberty humans are infertile as their genitals lack reproductive function only being able to discharge urine Legal factors also play a vital role in the achievement of human reproduction a minor under the age of consent cannot give legal consent to sexual intercourse or artificial alternatives to reproduction the former case of which is liable to have the older party charged with statutory rape depending on jurisdictions 5 6 Even for minors above the age of consent comprehensive sex education advises both consenting parties to use contraception to avoid both sexually transmitted diseases and early unplanned unwanted pregnancies Pregnancy in girls under the age of 15 is especially discouraged due to their reproductive systems having yet to reach full maturity 7 Anatomy EditFurther information Human reproductive system Male reproductive system Edit Further information Male reproductive system The male reproductive system contains two main divisions the testes where sperm are produced and the penis which discharges the sperm as semen this is known as an ejaculation In humans both of these organs are outside the abdominal cavity Having the testes outside the abdomen facilitates temperature regulation of the sperm which require specific temperatures to survive about 2 3 C less than the normal body temperature i e 37 C In particular the extraperitoneal location of the testes may result in a 2 fold reduction in the heat induced contribution to the spontaneous mutation rate in male germinal tissues compared to tissues at 37 C 8 If the testicles remain too close to the body it is likely that the increase in temperature will harm the spermatozoa formation making conception more difficult This is why the testes are carried in an external scrotum rather than within the abdomen they normally remain slightly cooler than body temperature facilitating sperm production Female reproductive system Edit Further information Female reproductive system The female reproductive system likewise contains two main divisions the external genitalia and the internal genitalia The ovum meets with the sperm cell a sperm may penetrate and merge with the egg fertilizing it with the help of certain hydrolytic enzymes present in the acrosome The fertilization usually occurs in the oviducts but can happen in the uterus itself The zygote then becomes implanted in the lining of the uterus where it begins the processes of embryogenesis and morphogenesis When the fetus is developed enough to survive outside of the uterus the cervix dilates and contractions of the uterus propel it through the birth canal which is the vagina and thereby gives external life to the newborn infant This process is called childbirth The ova which are the female sex cells are much larger than the spermatozoon and are normally formed within the ovaries of the female fetus before birth They are mostly fixed in location within the ovary until their transit to the uterus and contain nutrients for the later zygote and embryo Over a regular interval known as the menstrual cycle in response to hormonal signals a process of oogenesis matures one ovum which is released and sent down the Fallopian tube If not fertilized this egg is flushed out of the system through menstruation Process of fertilization Edit Basic processes involved 1 maturity 2 spermatogenesis and oogenesis 3 vaginal intercourse with internal fertilization 4 zygote 5 embryonic development 6 childbirth 7 adolescence Coition of a Hemisected Man and Woman c 1492 by Leonardo da Vinci Human reproduction normally begins with copulation though it may be achieved through artificial insemination and is followed by nine months of pregnancy before childbirth Pregnancy can be avoided with the use of contraceptives such as condoms and intrauterine devices 9 Copulation Edit Main article Sexual intercourse Human reproduction naturally takes place as internal fertilization by sexual intercourse During this process the man inserts his erect penis into the woman s vagina and then either partner initiates rhythmic pelvic thrusts until the man achieves orgasm which leads to ejaculation of semen containing sperm into the vaginal canal The sperm and the ovum are known as the gametes each containing half the genetic information of the parent created through meiosis 2 The sperm being one of approximately 250 million sperm in a typical ejaculation travels through the vagina and cervix into the uterus or Fallopian tubes Only 1 in 14 million of the ejaculated sperm will reach the Fallopian tube The egg simultaneously moves through the Fallopian tube away from the ovary One of the sperm encounters penetrates and fertilizes the ovum creating a zygote Upon fertilization and implantation gestation of the fetus then occurs within the uterus 10 11 12 13 Chance of fertilization by menstrual cycle day relative to ovulation 14 Pregnancy rates for sexual intercourse are highest during the menstrual cycle time from some 5 days before until 1 to 2 days after ovulation 15 For optimal pregnancy chance there are recommendations of sexual intercourse every 1 or 2 days 16 or every 2 or 3 days 17 Studies have shown no significant difference between different sex positions and pregnancy rate as long as it results in ejaculation into the vagina 18 Alternative methods Edit As an alternative to natural sexual intercourse there exists artificial insemination where sperm is introduced into the female reproductive system without the insertion of the penis 4 There are also many methods of assisted reproductive technology such as in vitro fertilization where one or more egg cells are retrieved from a woman s ovaries and co incubated with sperm outside the body The resulting embryo can then be reinserted into the womb of the woman citation needed Pregnancy Edit Main article Pregnancy Pregnancy is the period of time during which the fetus develops dividing via mitosis inside the uterus During this time the fetus receives all of its nutrition and oxygenated blood from the mother filtered through the placenta which is attached to the fetus abdomen via an umbilical cord This drain of nutrients can be quite taxing on the mother who is required to ingest slightly higher levels of calories In addition certain vitamins and other nutrients are required in greater quantities than normal often creating abnormal eating habits Gestation period is about 266 days in humans While in the uterus the baby first endures a very brief zygote stage then the embryonic stage which is marked by the development of major organs and lasts for approximately eight weeks then the fetal stage which revolves around the development of bone cells while the fetus continues to grow in size 19 It is estimated that about 3 5 of couples are infertile and the fecunditity of couples is around 30 for each menstrual cycle 20 Labor and birth Edit Newborn infant and mother Main article Childbirth Labor is separated into 4 stages The first stage involves latent phase and active phase separated by the dilation of the cervix for 6 to 10 cm The second stage is the pushing stage The third stage involves the delivery of the placenta And the last stage is the contraction of the uterus 21 Once the fetus is sufficiently developed chemical signals begin the process of birth which begins with the fetus being pushed out of the birthing canal The newborn which is called an infant in humans should typically begin respiration on its own shortly after birth Not long after the placenta eventually falls off on its own The person assisting the birth may also sever the umbilical cord Discovery of mechanism EditWhile most ancient human societies believed that sexual intercourse was necessary for reproduction the reasons some sex did not result in children and the mechanism by which mating produced children were not understood The theory of preformationism was popular in Ancient Greece and Christendom for centuries Because they are too small to see with the naked eye it was only after his invention of the microscope that Antonie van Leeuwenhoek discovered spermatozoa in 1677 Mitosis and meiosis were not discovered until the late 1800s See also EditHeterosexuality Antinatalism Evolution of sexual reproduction Female infertility Human Reproduction journal Journal of Human Reproductive Sciences Male infertility Natalism Paternal age effect Reproduction Reproductive system Legislation on human reproduction Reproductive healthReferences Edit a b c Jones Richard E 1991 The Male Reproductive System Human Reproductive Biology Elsevier pp 72 93 doi 10 1016 b978 0 12 389770 1 50008 1 ISBN 9780123897701 archived from the original on 2022 09 12 retrieved 2022 09 12 a b c Gametogenesis an overview ScienceDirect Topics www sciencedirect com Retrieved 2022 09 12 Embryogenesis an overview ScienceDirect Topics www sciencedirect com Retrieved 2022 09 13 a b Ombelet W Van Robays J 2015 Artificial insemination history hurdles and milestones Facts Views amp Vision in ObGyn 7 2 137 143 ISSN 2032 0418 PMC 4498171 PMID 26175891 Carmen M Cusack 2015 Laws Relating to Sex Pregnancy and Infancy Issues in Criminal Justice Springer p 10 ISBN 978 1137505194 Archived from the original on May 9 2021 Retrieved August 31 2021 Voluntary sexual intercourse with a post pubescent minor who is younger than the legal age of consent is described as statutory rape In most states age of consent is delimited between 16 years old and 18 years old In almost every jurisdiction prepubescent children may not engage in any sexual contact Engaging in sexual contact with a prepubescent child is a serious criminal offense and a felony Statutory Rape Known to Law Enforcement PDF U S Department of Justice Office of Juvenile Justice and Delinquency Prevention Archived PDF from the original on 2007 10 21 Retrieved 2021 08 31 Mayor S 2004 Pregnancy and childbirth are leading causes of death in teenage girls in developing countries BMJ 328 7449 1152 doi 10 1136 bmj 328 7449 1152 a PMC 411126 PMID 15142897 Baltz RH Bingham PM Drake JW 1976 Heat mutagenesis in bacteriophage T4 The transition pathway Proc Natl Acad Sci USA 73 4 1269 1273 Bibcode 1976PNAS 73 1269B doi 10 1073 pnas 73 4 1269 PMC 430244 PMID 4797 a href Template Cite journal html title Template Cite journal cite journal a CS1 maint multiple names authors list link Teal Stephanie Edelman Alison 2021 12 28 Contraception Selection Effectiveness and Adverse Effects A Review JAMA 326 24 2507 2518 doi 10 1001 jama 2021 21392 ISSN 0098 7484 PMID 34962522 S2CID 245557522 Archived from the original on 2022 08 26 Retrieved 2022 09 12 Ghazal S Kulp Makarov J et al 2014 Egg Transport and Fertilization The Global Library of Women s Medicine doi 10 3843 GLOWM 10317 ISSN 1756 2228 Archived from the original on May 13 2016 Retrieved May 8 2016 a href Template Cite journal html title Template Cite journal cite journal a CS1 maint multiple names authors list link Conception How It Works The Regents of The University of California 2002 Archived from the original on March 15 2016 Retrieved May 8 2016 Fertility Basics Complete Fertility Centre Southampton Complete Fertility Ltd 2015 Archived from the original on May 8 2016 Retrieved May 8 2016 Conception amp Pregnancy Ovulation Fertilization and More WebMD LLC 2016 Archived from the original on May 8 2016 Retrieved May 8 2016 Dunson D B Baird D D Wilcox A J Weinberg C R 1999 Day specific probabilities of clinical pregnancy based on two studies with imperfect measures of ovulation Human Reproduction 14 7 1835 1839 doi 10 1093 humrep 14 7 1835 ISSN 1460 2350 PMID 10402400 Pages 242 374 in Weschler Toni 2002 Taking Charge of Your Fertility Revised ed New York HarperCollins pp 359 361 ISBN 0 06 093764 5 How to get pregnant Mayo Clinic 2016 11 02 Archived from the original on 2020 05 18 Retrieved 2018 02 16 Fertility problems assessment and treatment Clinical guideline CG156 National Institute for Health and Care Excellence Archived from the original on 2018 02 17 Retrieved 2018 02 16 Published date February 2013 Last updated September 2017 Dr Philip B Imler amp David Wilbanks The Essential Guide to Getting Pregnant PDF American Pregnancy Association Archived from the original PDF on 2018 06 01 Retrieved 2018 02 16 Feist Gregory J Rosenberg Erika L 11 October 2011 Psychology Perspectives and Connections Second ed McGraw Hill pp 171 172 ISBN 978 0 07 803520 3 Spira A February 1986 Epidemiology of human reproduction Human Reproduction Oxford England 1 2 111 115 doi 10 1093 oxfordjournals humrep a136353 ISSN 0268 1161 PMID 3549765 Archived from the original on 2022 06 15 Retrieved 2022 09 12 Liao John B Buhimschi Catalin S Norwitz Errol R June 2005 Normal labor mechanism and duration Obstetrics and Gynecology Clinics of North America 32 2 145 164 vii doi 10 1016 j ogc 2005 01 001 ISSN 0889 8545 PMID 15899352 Archived from the original on 2022 06 15 Retrieved 2022 09 12 Altrui The Human Egg Cell ExplainedFurther reading EditHopwood Nick Rebecca Flemming Lauren Kassell eds Reproduction Antiquity to the Present Day Cambridge UP 2018 Illustrations xxxv 730 pp ISBN 978 1 107 06802 5 excerpt also online review 44 scholarly essays by historians Dolnick Edward 2017 The Seeds of Life From Aristotle to da Vinci from Sharks Teeth to Frogs Pants the Long and Strange Quest to Discover Where Babies Come Basic Books ISBN 978 0465082957 Retrieved from https en wikipedia org w index php title Human reproduction amp oldid 1148559987, wikipedia, wiki, book, books, library,

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