G estation

1. Gestation Maria Paula Ramirez and Jaime Andres Gonzales 10 o

2. What is gestation? • The term gestation is used in zoology to describe he time between conception and birth, during which the embryo or fetus is developing in the uterus. In other words when a female viviparous animal carries and supports a breeding embryonic or fetal in its belly till the time of delivery. Among mammals, there are species with multiple gestations who are born in more than one brood each end of gestation. The duration-called gestational period, is the duration of the breeding intrauterine development and varies from species

3. Structural stuff

4. Components • Uterine epithelium: lining in the uterus made of blood and nutrients, here the fertilized egg implants. • Epiblast: differentiates from the cell mass, becomes a bilaminar disc, the ectoderm, and finally the amnion. • Hypoblast: differentiates from the cell mass, becomes a bilaminar disc, the endoderm, and finally the yolk sac and the digestive track. • Thropoblast: divides from the fertilized ovule, becomes the choroid and the villi that attaches to the epithelium. • Mesoderm: differentiates from the hypoblast and Thropoblast in the bilaminar disc, becomes the embryo and the umbilical cord. • Uterine wall: found under the lining, filled with capillaries, comes in contact with the villi so close that blood and nutrients pass through diffusion. • Chorion: sac that surrounds the placenta, is the outer membrane and bonds the villi. • Amnion: sac that holds the embryo/foetus, contains amniotic fluid and is inside the choroid. • Umbilical cord: tube that passes arteries and veins that connect to the villi, connects the baby to its mother. • Placenta: organ formed in pregnancy that comprehends the permeated uterine lining, the choroid and the villi. • Amniotic fluid: aqueous substance that holds the embryo/foetus, works as air to develop the lungs, digestive track and vascular system.

6. Gestation in humans • Gestation: period of forty-week, which takes place on the development of the embryo to complete their training which takes place during the formation of all organs.Human pregnancy can be divided into three trimesters. The third trimester begins at approximately 28 weeks after fertilization. It is considered viable when a human fetus have passed 23 weeks gestation. Before this gestational age, the main events of embryonic development is not yet allowing fetal survival outside the womb. This limit is often arbitrary for the reason that some children born before this point have survived, althoug with considerable medical support. • The human birth occurs between 37 and 42 weeks gestational age. Labor that occurs before 37 weeks is considered premature and is considered viable after 25 weeks.

7. Development of the mother and baby during gestation • After fertilization, many changes occur in the body of the pregnant woman because the baby's development in utero produces large biochemical changes. For this reason, moms are beginning to see many signs associated with pregnancy.The first is the lack of menstruation, but as not all women have regular periods is important to note other signs such as enlarged breasts, nausea, heartburn, fatigue or tiredness or frequent urination. However, it is important for women to confirm the diagnosis with a pregnancy test, although present all the symptoms, and see your doctor.Pregnancy tests can detect the presence of a hormone called human chorionic gonadotropin, which is produced by the placenta and is present in the blood and urine of pregnant women.

8. Beginning of the gestation of the baby • The life of your baby begins when a sperm fertilizes one of your eggs. After half an hour, the fertilized egg is dividing into numerous cells while traveling down the fallopian tube toward the uterus to implant in the uterine wall where it will continue its development. At three weeks, the embryo has a tiny heart begins to beat. At the end of the fourth week, the head is easily recognizable, which has a rudimentary brain and begin to recognize also the arms and legs.

9. 1-4 weeks • Ovulation occurs: the egg needs to be fertilizated • Conception Occurs: the uterus will increase its capacity by 1000 times • Gender is determined: immediately after fertilization the fetus is set as a boy or a girl. The sperm determines the gender of the baby, because it carries a X for girls chromosome or a Y for boys chromosome +. The gender will be visible in the second trimester via the ultrasound. • Implantation: some implantation bleeding may occur about 10-14 days after conception. It’s not menstruation; generally this bleeding is extremely light and lasts one day or so. • Neural tube forms: in this period of pregnancy, it will develop into the nervous system: brain, spinal cord, hair and skin. And the baby has already the foundation for thought, senses, feeling and more. • Also in this period, heart and primitive circulatory system is rapidly formed, this is the support system that would carry the baby through his or her life.

10. Week 5 • The first heartbeats begin. • The umbilical cords develops this is the baby’s lifeline in the uterus. Its bears the responsibility of pumping oxygen, removing waste, and supplying the necessary nutrients for the rest of the pregnancy. • In week five of pregnancy, blood is know pumping. The four heart chambers are functioning, for that the body of the baby will receive all its needs , through the remaining of the pregnancy and life. • Most of others organs begin to develop. The lungs start to appear along with the brain. • Arms and leg buds appear at 5 weeks of pregnancy.

11. Week 6 • Thearms and legscontinuetodevelop. Theselimbs are stretchingout more and more. • Brainisgrowingwell, duringtheremainingmonthsthebabysbrainwilldevelopover 100 billionneurons • Thelenses of theeyesappear in this time • Nostrils are formed • Theintestinesgrow at the 6 week of pregnancy; at thebeginningthese are locatedoutsidethebaby’sbodywithinthe umbilical cord • Pancreas. Knowthebabyisequippedtodealwithdigestiveenzymes and takeonprocessingtheinsulin and glucagonsthebodyneedstofunction.

12. Week 7 • Elbows form   • Fingers start to develop; these digits often become the baby’s first toy •  Feet start to appear with tiny notches for the toes •  Ears, eyes and nose start to appear •  Intestines start to form in the umbilical cord, initially the intestines are not form inside the baby’s body •  Teeth begin to develop under the gums

13. Week 8 • Cartilage and bones begin to form, at the end of the week the baby have already completed 1/5 of the journey till de birth day. •  They basic structure of the eye is wll underway •  The tong begins to develop • Intestines move out of the umbilical cord into the abdomen •  Body grows and makes room • The fingers and toes have appeared but are short and webbed •  The baby’s height is about 0.61 inch, 1.6 cm and weightisabout 0.04 ounce, 1 gm.

14. Week 9 • Baby has begun movement. But pregnant women can’t feel that moment • Most joints are formed know, the baby is practicing bending and flexing • The fetus will curve its fingers an object placed in the palm of its hand. • Fingerprints are already evident in the skin • The length of the baby is about 0.9 inch that is 2.3 cm and 0.07 ounce that is 2gm

15. Week 10 • Baby is now called a fetus in “medical terms” • The most critical part of your infants developments is complete, now a period of rapid growth is coming • The head of the baby is now about half its length. The rest of the body growth will catch up but this area is prepared to keep up with the brain development • Eyelids uses shuts and irises begin to develop, eye color is also determine in this time • Placenta begins to function during this week or next. The placenta is the organ responsible for the provision of nutrients and the removal of waste to keep the baby grow strong • The baby will be about 1.22 inch long that is 3.1 cm and weight about 4 grams that are 0.14 ounce .

16. Week 11 • Nearlyallthestructures and organs are formed and theystarttofunction • Fingers and toes haveseparated • Hair and nailsbegintogrow • Thegenitalsbegintotakeonthepropergendercharacteristics, in somefewweekstheultrasound can show thegender of thebaby • Amniotic fluid beginstoaccumulate as thekidneysbegintofunction. This fluid thatisformedmostlybywaterhelpstoprovide a cushionforyourbabywhile he orsheiswithinthewomb • Themuscles in the intestinal wallsbegintocontractdigestingfood • Thebabyisabout 1.61 inchesthat are 4.1 cm long and itweighs 0.25 ouncesthat are 7 gm

17. Week 12 • Vocal cordsbegintoform • Theeyesbegintomoveclosertogether • Earsshifttotheir normal place ontheside of the head • Intestinesmovefurtherintothechild’sbody • Hisorherliverbeginstofunction, thatisresponsibleforcleansingtheblood, storingnutrients and itprovidessome fundamental chemicals • Thepancreasbeginsto produce insulin • Thebaby’slengthisabout 2.13 inchesthat are 5.4 cm long and itweights 0.49 ouncethatis 14 gm

18. Week 13 • Thebabyisabout 2.91 incheslongthatis 7.4 cm and itweightsaround 0.81 ouncethatisabout 23 mg • Thebabybeginspracticinginhaling and exhalingmovements • Eyes and earscontinuedeveloping • Baby’sneckisgettinglonger so the chin is no longerresting in hischest • Hishands are becoming more functional • Baby’sreceiveallnourishmentfromthe placenta • Themothershouldheartheheartbeat of thebabywith a Doppler

19. Week 14 • Thethyroidgland has matured and thebabybeginsproducing hormones thatwouldbeusedduringhisorherlife • In theboystheprostateglandsdevelops • In thegirlstheovariesmovefromthe abdomen tothe pelvis • Thebones are gettingharderstronger and harder • Lanugo thatis a very fine haircoversthebaby’sbody and willcontinuegrowingfor 11 weeks more, itprotectsthebabyskin • Yourbabyis 3.42 inches (8.7cm) long and weighsabout 1.52 ounces (43 grams)

20. Week 15 • Themother can starttofeelsomeflutteringmovements as babykicks, flails, twists and turn. • Thelegs of thebabyhavegrownlongerthanthearms and thebodyisnowlongerthanthe head • Thebabyismovingthearms and legscontinuously • Theskin of thebabyisveryweak, so thinbloodvessels are visible. Itscoveredby a layercalled lanugo thathelpstoinsulatethechild. • Thethreebones in themiddleearhavebeguntoharden, buttheauditory center in thebrainhaven’tdevelopyet • Fingernails and toenails are growing • Eyebrows are beginningtogrow • Thebabyisabout 3.98 inches and 2.47 ounces

21. Week 16 • Fatbeginstoformunderneathskin, providingthebabywithinsulationforthenextmonths • Thebaby and the placenta are knowaboutthesamesize • Thebabyisabout 4.57 inches and 3.53 ounces • His head and neck are heldstraighternow • Themother can heartheheartbeatswith a external monitor know • Thegenitals are developedsufficientlythatanexperiencedsonographermigthbeableto determine thegender of yourbaby • Theheart of thebabyispumpingabout 6 gallons of blood a day • Thebabystartstodevelop more itsreflexessuch as sucking, swallowing and blinking n • Thebaby has learnedtobreathe. Thisisfromthe regular movements of hischest. Thebabyinhals and exhalssmallamounts of amniotic fluid thathelpsthelungstodevelop

22. Week 17 • Thebabyweightsabout 4.97 ounces and itis 5.12 incheslong • Pads are formingonhisfingerprints and toes • Herorhiseyes are looking forward know, butthey are stillclosed • Meconioumthatiscomposed of products of cellloss, digestivesecretion and swallowedamniotic fluid, accumulates in thebowel. Thiswillbecomethebaby’sfirstpoop • The umbilical cordisgrowingthicker and stronger and itcontinuesprovidingblood and nutrientstothegrowingbaby • Ifthechildis a male, theprostatebeginstodevelop • Herorhisskeletonistransformingfromcartilagetobone, butthebonesremain flexible tomakethejourneythroughthebirth canal easier.

23. Week 18 • Vernixisformed in thebaby’sskinwiththe lanugo, theybothprotecttheskin of thebaby • The placenta continuesgrowing and nourishingthebaby • Sometiny air sacscalledalveolibegintoform in thelungs • Herorhis vocal chords are formed, he orshecriesbutwithout air he orshedoesn’tmakeanysound • Ventricles and chambersshouldbe visible duringultrasound • Thebabywouldmeasureabout 5.59 inches and weightabout 6.7 ounces

24. Week 19 • The baby can now hear sounds and make more movements while the mother can feel fluttering in her abdomen. The intestines are now fully developed to absorbed small amounts of sugar from the digestive system of the mother.

25. Week 20 • The different senses are now slowly developing. The baby’s sense of taste has started to develop and brain’s nerve endings are fully developed that the baby can sense touch. The entire body will be covered by lanugo. Nails will grow as well as the eyebrows and lashes. Heartbeat can now be heard through a stethoscope and fetus will become more active as muscles continue to develop.

26. 12-23 weeks • Low chances of abortion • The gender is not highly differentiated, genitals are simple identical bulbs, but in different angles (this becomes the penis or the clitoris) • The hands develop first as the fingers separate and the bone begins to strengthen • The central nervous system has spread throw-out the body and the first prehensile reflex is evident • The baby becomes very active, as it has a working digestive apparatus, and the mother begins to feel the foetus's movements.

27. 24 week • The foetus is viable to born, with medical aid, since the 22 week, but this might have future effects on mental development • The mother has no longer morning sickness, is energetic and its abdomen grows • Senses begin to develop, specially hearing, taste and smell, as the mothers food taste might reach the baby through the ingestion of the amniotic fluid.

28. 25 week • The baby's motor functions begin to develop, as they shall for the rest of its life • Eye colour begins to be formed, as some pigments require light to finish, most will look clear and pallid, but will darken with time.

29. 26 week • The baby's heart can be heard at this time, which beats at twice the speed of its mother • The foetus is only awake 10% of the time • The last organ to develop is the lungs which are not used until child birth

30. 28-37 week • Brain cortex matures enough to retain memories • The foetus position changes to have the head down against the cervix • The organs are all functional, and the liver begins to process waste products while self body regulations begin

31. 38-40 weeks • Birth is likely to occur • When the foetus lungs are fully developed, a protein is released, that lowers the hormone progesterone, but increases oxytocin, that produces contractions and is known to block memories of pain • Birth is the most stressful moment of gestation • Birth: • The cervix dilates 10 cm • Contractions push the baby through the birth canal • The placenta is expelled.

32. Bibliography • http://www.babyzone.com/pregnancy/week/ • http://en.wikipedia.org/wiki/Pregnancy • http://en.wikipedia.org/wiki/Gestation • http://en.wikipedia.org/wiki/Fetus • http://en.wikipedia.org/wiki/Placenta

33. Bibliografy • http://www.americanpregnancy.org/duringpregnancy/calculatingdates.html • http://www.britannica.com/EBchecked/topic/232124/gestation • http://emedicine.medscape.com/article/259269-overview • http://www.goatbiology.com/animations/gestcalculator.html • http://www.thefreedictionary.com/gestation • http://www.medterms.com/script/main/art.asp?articlekey=3589