3rd Lecture-Conception & Fetal Development PDF

Conception & Fetal Development 3rd Lecture Maternity and Childhood Nursing Department Conception & Fetal Development Learning Outcomes: 1. Describe the growth and development of a fetus by gestation week. 2. Assess fe...

Conception & Fetal Development 3rd Lecture Maternity and Childhood Nursing Department Conception & Fetal Development Learning Outcomes: 1. Describe the growth and development of a fetus by gestation week. 2. Assess fetal growth and development through maternal and pregnancy landmarks. 3. Integrate knowledge of fetal growth and development with nursing process to achieve quality maternal and child health nursing care. Maternity and Childhood Nursing Department  In case of fertilization At time of ovulation, the cervical mucous becomes less viscous and providing channels for sperms passage. The sperms ascent through the uterine cavity and Fallopian tubes to reach the site of fertilization in the ampulla The ovum leaves the ovary after rupture of the Graafian follicle, the ovum is picked up by the fimbrial end of the Fallopian tubes and moved towards the ampulla After penetration of the ovum by a sperm, resistant to penetration by another sperms occur Maternity and Childhood Nursing Department  Sex Determination Ovum usually fertilized within 12-24 hours of ovulation; however, sperm remain alive for up to 72 hours within the female genital tract. The moment the sperm penetrates the egg is called conception, creating a new and separate cell called the Zygote. The mature ovum carries 22 autosomes and one X chromosome, while the mature sperm carries 22 autosomes and either an X or Y chromosome. If the fertilizing sperm is carrying X chromosome the baby will be a female (46 XX), if it is carrying Y chromosome the baby will be a male (46 XY). Maternity and Childhood Nursing Department Fraternal (dizygotic) twins: Two separate ova fertilized by two different sperm Identical (monozygotic) twins: Single fertilized ovum Maternity and Childhood Nursing Department Germinal Period (conception - 2 weeks) Oocyte (female germ cell) released from ovary and travels to uterine tube. Sperm fertilizes oocyte in uterine tube. Zygote travels up uterine tube, dividing continuously, creating blastomere (group of cells). Morula (minimum 12-16 cells) attaches to endometrium (posterior wall of uterus) after approximately 6 days. Blastocyst (attached morula) sinks into endometrium for approximately 7 days, completing implantation. Maternity and Childhood Nursing Department Maternity and Childhood Nursing Department  Implantation Trophoblast Blastocyst adhering to the uterine wall. Slow process occurring 5 - 9 days after the beginning of fertilization. Chorion Trophoblast cells produce enzymes (HCG) that allow blastocyst to burrow into endometrium. Maternity and Childhood Nursing Department  Human Chorionic Gonadotropin (HCG):  Source: Trophoblasts of blastocyst & Chorion (effects similar to LH). Target & Functions: Corpus Luteum Maintains corpus luteum & causes it to continue producing progesterone in the absence of LH through first four months of pregnancy till placenta produces sufficient estrogen & progesterone to maintain the pregnancy This maintains endometrium, prevents menstruation Can be detected by week 3 with a home pregnancy test (Basis of pregnancy test). Maternity and Childhood Nursing Department  Stages of Prenatal Growth Embryonic Period (3 – 8 weeks) Embryo forms different layers of cells Ectoderm – outside layer; becomes nervous system, sensory receptors, and skin Mesoderm – middle layer; becomes circulatory system (heart begins to beat at 4 weeks), muscles, bones, excretory system, and reproductive system Endoderm – inner layer; becomes digestive system and respiratory system. High risk of congenital malformation Maternity and Childhood Nursing Department Periods of Prenatal Growth & Development Period Length Key Events Fertilization Zygote& Pre Implantation embryonic 2 weeks Start of Placenta period Arms, legs, face, organs, muscles all develop Embryo 3-8 weeks Heart begins beating “Growth and finishing” Fetus 9 wk to birth Sex organs develop Maternity and Childhood Nursing Department  ‫‪Stages of Human Growth - Prenatal‬‬ ‫‪ Zygote‬‬ ‫‪ ‬قال تبارك و تعالى‪" :‬و لقد خلقنا اإلنسان من ساللة من طين (‪)12‬‬ ‫ثم جعلناه نطفة في قرار مكين (‪ )13‬ثم خلقنا النطفة علقة فخلقنا‬ ‫‪ Morula‬‬ ‫العلقة مضغة فخلقنا المضغة عظاما فكسونا العظام لحما ثم أنشأناه‬ ‫خلقا آخر‪ ،‬فتبارك هللا أحسن الخالقين (‪ ).)14‬سورة المؤمنون(‬ ‫‪ Blastocyst‬‬ ‫‪ ‬قال البيان القرآني‪ :‬يا أيها الناس إن كنتم في ريب من البعث فإنا‬ ‫خلقناكم من تراب ثم من نطفة ثم من علقة ثم من مضغة مخلقة‬ ‫‪ Embryo‬‬ ‫وغير مخلقة لنبين لكم ونقر في األرحام ما نشاء إلى أجل مسمى‬ ‫‪ Fetus‬‬ ‫(الحج ‪)5:‬‬ ‫مر بالنطفة اثنتان وأربعون‬‫‪ ‬قال الرسول صلى هللا عليه وسلم‪" :‬إذا ّ‬ ‫ليلة بعث هللا إليها مل ًكا فصورها‪ ،‬وخلق سمعها وبصرها وجلدها‬ ‫رب أذكر أم أنثى؟" صحيح مسلم‬ ‫ولحمها وعظامها‪ ،‬ثم قال‪ :‬يا ّ‬ ‫‪Maternity and Childhood Nursing Department‬‬  Stages of Development Organogenesis (1st trimester) Rudimentary organs and structures laid down Integration (2nd trimester) Physiological structures begin to connect into systems and work together Growth and Integration (3rd trimester) Rapid increase in size and increased maturation of structures and systems Maternity and Childhood Nursing Department  PLACENTA Remarkable organ originating from trophoblast layer of fertilized ovum. Functions: fetal respiration, and hormone excretion and produces glycogen, cholesterol and fatty acids, ad hormones hCG, hPL estrogen and progesterone, Transport, Nutrient function, Storage, Barrier function Divided into sections or segments called “Cotyledons”. Two sides: 1) Fetal side- shiny and smooth in appearance, the amniotic sac is attached to it. 2) Maternal side- dark red and rough in appearance. Maternal and Fetal blood do not mix Maternity and Childhood Nursing Department Maternity and Childhood Nursing Department  Fetal Membranes (amniotic Sac) Called the Bag of Waters Consists of two layers 1) Amnion- inner membrane, next to fetus 2) Chorion- outer membrane, next to mother Function: to house the fetus for the duration of pregnancy, protects from outside world, prevents vertical transmission of infection. Maternity and Childhood Nursing Department  Umbilical Cord The lifeline between mother and fetus Length 15-120 cm (average 50cm) sufficient to allow delivery of baby without traction to placenta occur. Contains 3 vessels: 2 arteries and 1 vein, which are protected by “Wharton’s Jelly”. If abnormal # of vessels present- often associated with fetal anomalies (heart and kidneys). The arteries carry “dirty blood” away from fetus. The vein carries “clean” blood to fetus. Central insertion into the placenta is normal No nerves in the cord Maternity and Childhood Nursing Department  Amniotic Fluid (liquor) Amniotic fluid is made up mainly from fetal urine (99% water) , fluid from maternal blood, castoff cells, vernix, and fetal waste products. It’s function is to cushion fetus and protect from injury, to keep infant at stable 37° temperature, to allow room for fetal movement and growth. Normal volume- 500 to 1000 ml at term. Clear, oder, pale straw, yellow or greenish colored PH 7.22 in early pregnancy but less than that at term (7.11), sterile to prevent infection (important for diagnosis of spontaneous rupture of membrane). Maternity and Childhood Nursing Department Milestones of Fetal Growth and Development End of 4-5th G/W End of 9th G/W End of 13th G/W (First Trimester) End of 17th G/W End of 21th G/W End of 25-26th G/W (Second Trimester) End of 30th G/W End of 34nd G/W End of 38-42th G/W (Third Trimester) Maternity and Childhood Nursing Department End of 4-5th Gestational Week (First month) Heart begins to beat approximately 85 beats /minute; Weight: 400 mg; Length: 0.75–1 cm Upper limb buds Lungs begin to form Parts of gastro intestinal tract can be identified. Placenta is forming by end of fourth week. Maternity and Childhood Nursing Department  End of 9th Gestational Week (Second month) Circulatory system through umbilical cord well established Organogenesis is complete) Abdomen appears large because the fetal intestine is growing rapidly. Sonogram shows a gestational sac, diagnostic of pregnancy Maternity and Childhood Nursing Department Fetal circulation. Maternity and Childhood Nursing Department  End of 13th Gestational Week (First Trimester) Fetal circulation functioning Begins to produce urine Fetal heart can be heard by electronic devices Ossification of bones are forming the fetus has all its body parts growth is rapid Maternity and Childhood Nursing Department End of 17th Gestational Week (Four Months) Baby is covered with a layer of thick, downy hair called lanugo. Liver and pancreas are functioning. Baby's first kick. Sex can be determined by ultrasound. Maternity and Childhood Nursing Department  End of 21st Gestational Week (Five Months) Spontaneous fetal movements can be sensed by the mother. A protective coating called vernix caseosa begins to form on baby's skin. The hair forms on the head, extending to include eyebrows. Meconium is present in the upper intestine. Brown fat, a special fat that will aid in temperature regulation at birth, begins to be formed behind the kidneys, sternum, and posterior neck. Start to sleep Maternity and Childhood Nursing Department End of 25-26 th Gestational Week (Second Trimester) Eyebrows and eyelids are visible. Baby's started breathing motions; Active production of lung surfactant begins. (Viability age: 24wks). If you talk or sing, he can hear you. Maternity and Childhood Nursing Department End of 30th Gestational Week (Seven Months) Baby weighs about 1,200 gm and is about 35 cm long. His body is well-formed. Fingernails cover his fingertips. Lung alveoli begin to mature & surfactant can be demonstrated in amniotic fluid. Testes starts to descend into the scrotal sac from the lower abdominal cavity Maternity and Childhood Nursing Department End of 34 Gestational Week (Eight Months) Baby is gaining about 125 gm per week, and layers of fat are piling on. Turned head-down in preparation for birth. Body stores of glycogen, iron, carbohydrate, and calcium are deposited. Maternity and Childhood Nursing Department End of 38-42 Gestational Week (Third Trimester) Length: 48 to 52 cm (crown to rump, 35 to 37 cm) Weight : 2.5-4 Kg Fetus kicks actively, hard enough to cause the mother considerable discomfort. Maternity and Childhood Nursing Department  What parents want to know? 4 wks fetal heart begins to beat 8-12 wks- All body parts formed, heart beating audible with Doppler 16 wks- Sex can be determined 20 Wks:Mom may feel movement in her lower abdomen (quickening) which feels like bubbles or fluttering & FH audible with stethoscope. 26 wks- Lanugo, vernix, hair, movement, favorite position, sleep-awake pattern, suck, grasp; Fetus can hear sounds 28 wks- eyes open, breathe, surfactant developing Maternity and Childhood Nursing Department Any Questions????