5.-pregnancy-begins.pdf

1  PREGNANCY The state of carrying a developing embryo or fetus within the female body from conception to birth. 2  FERTILIZATION CONCEPTION/FERTILIZATION is the penetration of one ovum...

1  PREGNANCY The state of carrying a developing embryo or fetus within the female body from conception to birth. 2  FERTILIZATION CONCEPTION/FERTILIZATION is the penetration of one ovum by one sperm resulting in a fertilized ovum called zygote. The sex of a child is determined at the moment of conception by the male gamete. NIDATION is the process of burrowing of the developing zygote into the endometrial lining of uterus. This usually takes place 7-10 days after fertilization. 3  FERTILIZATION The union of the spermatozoon with the mature ovum It begins with when a sperm cell collides and ends with production of mononucleated single cell called the zygote OBJECTIVES  To initiate the embryonic development of the egg  To restore the chromosome number of the species 4  PREGNANCY SPECIAL STRUCTURES OF PREGNANCY FETAL MEMBRANES Arise from the zygote and holds the developing fetus as well as the amniotic fluid AMNIOTIC FLUID Clear yellowish fluid surrounding the developing fetus. Average amount = 1000 ml  Allows free movement of the fetus  Maintains the temperature  Provides oral fluid 5  PREGNANCY UMBILICAL CORD The connecting link between fetus and placenta Contains 2 arteries and 1 vein supported by mucoid material (Wharton’s jelly) to prevent kinking and knotting There are no pain receptors in the umbilical cord PLACENTA  Transient organ allowing passage of nutrients and water materials between mother and fetus  Also acts as an endocrine organ and as a protective barrier against some drugs and infectious agents 6  STAGES OF FETAL DEVELOPMENT NAME TIME PERIOD OVUM From ovulation to fertilization ZYGOTE From fertilization to implantation EMBRYO From implantation to 5 to 8 weeks FETUS From 5 to 8 weeks until term CONCEPTUS Developing embryo or fetus and placental structures throughout pregnancy AGE OF VIABILITY – the earliest age at which a fetus survives, if born, accepted as 20 weeks or at a point the fetus weighs at least 500 grams 7 APPROXIMATION OF THE GAMETES The ovum is fertilizable and capable only for 24 to 48 hours; the lifespan of the sperm is 48 to 72 hours. Site: the outer third of the fallopian tube, AMPULLA – the widest part of the tube. Out of the millions of sperm cells in the vagina at a single ejaculation, only thousands capacitated spermatozoa enter the uterine tube while only 300 to 500 reach the ovum. 8 APPROXIMATION OF THE GAMETES Tubal transport is facilitated by muscular contraction and aspiration action of the uterine tube It takes only a few minutes for the sperm to reach the fallopian tube 9 CONTACT & FUSION OF THE GAMETES CAPACITATION The process of physiological changes in a spermatozoa in order to have the ability to penetrate and fertilize the ovum. This is the process of undertaking in the sperm when inside the female genital tract influenced by the secretion of the uterine tube. The sperm must be in the female genital tract 4-6 hours before they can fertilize an ovum. The sperm undergoes changes in the removal of the glycoprotein coat. 10 CONTACT & FUSION OF THE GAMETES ACROSOMAL REACTION The acrosomal layer of the sperm becomes reactive and releases the enzyme hyalurodinase known as the acrosome reaction. It disperses the corona radiata (the outer layer of the ovum) allowing access to the zona pellucida. 11 CONTACT & FUSION OF THE GAMETES CORTICAL REACTION The first sperm that reaches the zona pellucida penetrates it. Penetration of the zona pellucida occur with the aid of several enzymes processed by the sperm which break down the proteins of the zona layer. Upon penetration, a chemical reaction known as the cortical reaction occurs which makes it impermeable to other sperms. 12 CONTACT & FUSION OF THE GAMETES When a sperm unites with the egg’s plasma membrane, it alters the zona pellucida preventing other sperm from binding to and entering the egg. Acrosome reaction is the release of hydrolytic enzymes to soften the zona pellucida (jelly coat). Cortical reaction is the hardening of the jelly coat after fertilization to prevent the entry of the other sperm cells. 13 CONTACT & FUSION OF THE GAMETES ZYGOTE DEVELOPMENT The male and the female gametes each contribute half the complement of the chromosomes to make a total of 46. The new cell is called zygote. The zygote contains both the paternal and maternal genetic materials The sex of a child is determined by the pattern of the sex chromosome supplied by the spermatozoon. 14  ZYGOTE DEVELOPMENT Zygote development happens in three periods: 1. Pre – embryonic period: first two weeks after fertilization 2. Embryonic period: 2 to 8 weeks 3. Fetal period: 8 weeks to birth 15 ZYGOTE DEVELOPMENT PRE-EMBRYONIC PERIOD The implantation of the zygote into the endometrium. The embryo takes 3 days to travel through the fallopian tube to reach the uterus. It takes another 3 days to get implanted, usually in the dorsal wall of the uterus. The embryo is about 1 week old when it gets implanted. 16 ZYGOTE DEVELOPMENT The zygote undergoes mitotic division and cellular replication known as cleavage resulting in the formation of smaller cells known as BLASTOMERE. Pre-embryonic period happens first 2 weeks after fertilization:  2 cells at day 1 – 30 hours  4 cells at 2 days, 8 by 2.5 days, 16 by 3 days and called MORULA (resembling a mulberry at 16 to 64 cell stage) 17 ZYGOTE DEVELOPMENT Cells bind tightly together in a process known as compaction. Next, cavitation occurs where the outermost cells secrete fluid into the morula and fluid filled cavity or blastocele appears and becomes blastocyst comprising of 58 cells. 18 ZYGOTE DEVELOPMENT BLASTULATION Development of the morula to the blastocyst has occurred by day 4 The blastocyst either becomes a trophoblast or inner cell mass The trophoblast becomes the placenta and chorion The inner cell mass becomes the fetus, amnion and the umbilical cord 19 ZYGOTE DEVELOPMENT IMPLANTATION Embedding of the embryo to the wall of the uterus Also called NIDATION Occurs in the endometrium of the anterior or posterior wall of the body near the fundus on the 6th day which corresponds to the 20th day of regular menstrual cycle. Implantation occurs through stages. 20 ZYGOTE DEVELOPMENT 1) APPOSITION Occurs through pinopod formation. Pinopods are long finger-like projections (microvilli) from the endometrial cell surface The pinopods absorb the endometrial fluid which is secreted by the endometrial gland cells. This fluid rich in glycogen and mucin provides nutrition to the blastocyst initially 21 ZYGOTE DEVELOPMENT 2) ADHESION Unless this fluid is absorbed, adhesion phase cannot occur Adhesion of blastocyst to the endometrium occurs through the adhesion molecules like integrin, selectin and cadherin (glycoproteins) 22 ZYGOTE DEVELOPMENT 3) PENETRATION & INVASION Occur through the stromal cells in between the gland and is facilitated by the histolytic action of the blastocyst. With increasing lysis of the stromal cells, the blastocyst is burrowed more and more inside the stratum compactum of the decidua. 23 EMBRYONIC AND FETAL STRUCTURES DECIDUA The endometrium during pregnancy It has 3 layers: a. BASALIS – lies directly under the embryo (portion where trophoblast establish communication with maternal blood vessels) b. CAPSULARIS – stretches or encapsulates the surface of the trophoblast c. VERA – the remaining portion of the uterine lining; parietalis 24 EMBRYONIC AND FETAL STRUCTURES CHORIONIC VILLI Miniature villi similar to probing fingers that appear on the 11th or 12th day They begin the formation of the placenta Consists of a central core of connective tissue and fetal capillaries 25 EMBRYONIC AND FETAL STRUCTURES Consists of 2 layers of trophoblast cells: CYTOTROPHOBLAST (middle or Langhan’s layer) – functions in early pregnancy to protect the growing embryo and fetus from infection SYNCYTIOTROPHOBLAST (syncytial layer) – produces HCG, somatomammotropin (HPL), estrogen and progesterone. 26 EMBRYONIC AND FETAL STRUCTURES HORMONES PRODUCED: HCG (human chorionic gonadotropin) – ensures that the corpus luteum of the ovary continues to produce estrogen and suppresses maternal immunologic response to avoid placental tissue rejection ESTROGEN – helps in mammary gland development, stimulates uterine growth 27 EMBRYONIC AND FETAL STRUCTURES PROGESTERONE – maintains endometrial lining, reduce contractility of uterine muscle preventing premature labor, decreases intestinal peristalsis = constipation HPL (human placental lactogen) – promotes mammary gland growth, regulates maternal glucose, protein, and fat levels; acts as glucose antagonist, so that glucose will be available for the fetus; diabetogenic hormone: can cause gestational diabetes 28 EMBRYONIC AND FETAL STRUCTURES PLACENTA  Serves as fetal lungs, kidneys, and GIT  Exchange happens thru selective osmosis thru the chorionic villi  Placental circulation most efficient when mother lies on her left  Weighs 400-600 grams at term, 15-20 cm in diameter, 2-3 cm deep  Mother transmits immunoglobulin G to fetus, limited passive immunity 29 EMBRYONIC AND FETAL STRUCTURES Has 25-30 cotyledons (placental compartments that lie on the maternal side) Has 2 sides: MATERNAL – dirty rough FETAL – shiny smooth It also secretes endocrine hormones 30 EMBRYONIC AND FETAL STRUCTURES HCG – 1st placental hormone Ensures corpus luteum to continuously produce progesterone and estrogen Suppresses maternal immunologic reaction so that placental tissue is not detected and rejected as a foreign substance If fetus is male, stimulates the testes to begin producing testosterone At 8 weeks, begins progesterone production and as a result, disintegrates corpus luteum and hCG production decreases 31 EMBRYONIC AND FETAL STRUCTURES ESTROGEN (estriol) – hormone of women Contributes to mammary gland development of mother in preparation for lactation Stimulates uterine growth to accommodate growing fetus PROGESTERONE – hormone for mothers Necessary to maintain endometrial lining of the uterus during pregnancy Reduces contractility of uterus during pregnancy preventing preterm labor 32 EMBRYONIC AND FETAL STRUCTURES HUMAN PLACENTAL LACTOGEN With both growth promoting and lactogenic (milk production) properties Promotes mammary gland growth in preparation for lactation Regulates maternal glucose, protein and fat levels so that adequate amounts of these are always available to the fetus 33 EMBRYONIC AND FETAL STRUCTURES THE PLACENTA BARRIER oSugar, fats and oxygen diffuse from mother’s blood to fetus oUrea and CO2 diffuse from fetus to mother oMaternal antibodies are actively transported across the placenta. Some resistance to disease is passed to the fetus (passive immunity) oMost bacteria are blocked 34 EMBRYONIC AND FETAL STRUCTURES oMany viruses can pass including rubella, chickenpox, sometime HIV oMany drugs and toxins pass including alcohol, heroin, and mercury 35 EMBRYONIC AND FETAL STRUCTURES UMBILICAL CORD Transports oxygen and nutrients to fetus and returns waste products from fetus to placenta Has 1 vein & 2 arteries: probably with congenital anomaly if incomplete About 55 cm long 2 cm diameter Wharton’s jelly – a gelatinous mucopolysaccharide that forms the bulk of the umbilical cord giving its body: prevents pressure on the vein and arteries 36 EMBRYONIC AND FETAL STRUCTURES 37 EMBRYONIC AND FETAL STRUCTURES AMNIOTIC MEMBRANES CHORIONIC MEMBRANE – the outermost fetal membrane forming the sac that contains the amniotic fluid AMNIOTIC MEMBRANE – 2nd membrane lining the chorionic membrane formed beneath the chorion. Produces amniotic fluid Produces phospholipids that initiates the formation of prostaglandins causing uterine contractions and trigger labor 38 EMBRYONIC AND FETAL STRUCTURES AMNIOTIC FLUID 800 – 1,200 ml at term > POLYHYDRAMNIOS (>2,000 ml) > OLIGOHYDRAMNIOS ( Demographic data > Menstrual history – menarche, regularity, frequency and duration of flow, last period > Obstetrical history – all pregnancies, complications, outcomes, contraceptive use, sexual history 104 NURSING CARE DURING PREGNANCY OBSTETRIC HISTORY/OB SCORE GRAVIDA – number of times she has been pregnant PARA – number of pregnancies that reached the age of viability regardless of whether infants were born dead or alive TERM – full term infants born ≥ 37 & 7 days PRETERM – infant born < 37 & 5 days ABORTION – spontaneous or induced abortion; ectopic pregnancy LIVE – living children MULTIPLE PREGNANCY – the total of multiple pregnancies 105 NURSING CARE DURING PREGNANCY EXAMPLE 1 May is 6 weeks pregnant. Her 2 previous pregnancies ended in a live birth at 41 weeks. G? T? P? A? L? 106 NURSING CARE DURING PREGNANCY EXAMPLE 2 Susan is experiencing her fourth pregnancy. Her first pregnancy ended in a spontaneous abortion at 8 weeks, the second resulted in the live birth of twin boys at 38 weeks, and the third resulted in the live birth of a daughter at 34 weeks. G? T? P? A? L? 107 NURSING CARE DURING PREGNANCY > Medical history – includes past illnesses, surgeries, current use of medications, any drug or food sensitivity, use of oral contraceptive, use of alcohol and tobacco, blood transfusion endocrine disorders, infections, diabetes, heart disease > Family history/Psychosocial data – ask for congenital disorders, hereditary diseases, multiple pregnancies, diabetes, heart disease, hypertension, mental retardation 108 NURSING CARE DURING PREGNANCY B. PHYSICAL EXAMINATION LEOPOLD’S MANEUVER – performed in pregnancy after the uterus becomes large enough to allow differentiation of fetal parts by palpation. Nursing Responsibilities: ask the woman to empty her bladder place woman in dorsal recumbent position abdomen uncovered whoever performs the maneuver warms hands prior to 109  NURSING CARE DURING PREGNANCY FIRST MANEUVER The superior surface of the fundus is palpated to determine consistency, shape and mobility. Also called FUNDAL GRIP Palms are placed at the uterine fundus Permits identification of which fetal pole (breech or head) – occupies the uterine fundus 110  NURSING CARE DURING PREGNANCY SECOND MANEUVER Both sides of the uterus are palpated to determine the direction the fetal back is facing. Palms are placed on either side of the maternal abdomen Gentle but deep pressure On one side a hard, resistant structure – the back (convex shape) On the other, numerous small, irregular, mobile parts – fetal extremities 111  NURSING CARE DURING PREGNANCY THIRD MANEUVER This determines the part of the fetus at the inlet and its mobility. Using the thumb and fingers of the right hand, the lower portion of the maternal abdomen is grasped just above the symphysis Movable mass – the presenting part is not engaged Differentiation between head and breech 112  NURSING CARE DURING PREGNANCY FOURTH MANEUVER This determines the fetal attitude and degree of the fetal extension into the pelvis. The examiner faces the mother’s feet With the tips of the fingers of each hand, exerts deep pressure in the direction of the axis of the pelvic inlet. 113  NURSING CARE DURING PREGNANCY DIFFICULT TO PERFORM ON: Obese women Women with polyhydramnios Primigravida with a very tight anterior abdominal wall Uncooperative women Leopold’s is performed after 24 to 26 weeks 114  NURSING CARE DURING PREGNANCY WEIGHT GAIN Total weight gain: 25 – 35 lbs in a woman of normal Body Mass Index First trimester: 1 lb per month; 3-4 lbs total Second trimester: 0.9 – 1 lb per week; 10-12 lbs Third trimester: 0.5 – 1 lb per week 115  NURSING CARE DURING PREGNANCY The pattern of weight gain is more important than the amount of weight gain Normal weight gain patterns contribute to health of both mother and fetus Failure to gain weight is an ominous sign Weight is a measure of health of a pregnant mother 116 NURSING CARE DURING PREGNANCY C. DIAGNOSTIC TESTS DURING PREGNANCY ALPHA – FETO PROTEIN LEVELS – assesses the presence of neural tube defects and Down’s syndrome ***Nursing Alert: An elevated AFP level indicates neural tube defects and a decreased level indicates Down’s syndrome 117 NURSING CARE DURING PREGNANCY AMNIOCENTESIS – to assess fetal growth and maturity, to determine genetic disorders, and sex of the fetus. ***NURSING ALERT If done between 14-16 weeks AOG, the purpose is to assess for chromosomal aberration or other disorders. If done after 35 weeks AOG, the purpose is to assess fetal lung maturity. 118 NURSING CARE DURING PREGNANCY Instruct patient to void if gestation is above 20 weeks Position patient in supine An L/S ratio 1:2 indicates fetal lung maturity Advise patient to report fetal movement, vaginal bleeding, chills, fever, fluid leakage and vaginal discharge Complications: placental, cord, and bladder puncture 119 NURSING CARE DURING PREGNANCY CHORIONIC VILLI SAMPLING – determines some genetic aberrations ***NURSING ALERT Instruct patient to drink water to fill the bladder to aid in the attainment of the desired position of the uterus Explain that the risks involved include: spontaneous abortion, infection, hematoma, and intrauterine death 120 NURSING CARE DURING PREGNANCY CONTRACTION STRESS TEST (OXYTOCIN CHALLENGE TEST) – indicates uteroplacental insufficiency and identifies pregnancies at risk ***NURSING ALERT Negative result indicates absence of abnormal decelerations with all contractions Positive result indicates abnormal fetal heart rate, decelerations with contractions 121  NURSING CARE DURING PREGNANCY TYPES OF CST NIPPLE STIMULATED CST – massage or rolling of one or both nipples to stimulate uterine activity and check effect on fetal heart rate INTRAVENOUS OXYTOCIN – IV oxytocin is incorporated in an IV fluid where the flow rate is controlled as needed; this stimulates uterine activity 122  NURSING CARE DURING PREGNANCY COOMBS TEST – determines if one has antibodies causing autoimmune reaction and destroy red blood cells DIRECT – used to test antibodies on patient’s erythrocytes INDIRECT – used to test antibodies on patient’s serum ***NURSING ALERT Positive direct Coombs test indicates erythroblastosis fetalis 123  NURSING CARE DURING PREGNANCY PROCEDURE Blood sample obtained through the vein and tested with compounds that will react with your antibodies This is also done on infants who may have antibodies in their blood because the mother has a different blood type Coombs positive babies are at higher risk for hyperbilirubinemia 124  NURSING CARE DURING PREGNANCY FETAL HEART MONITORING – assesses fetal heart rate abnormalities ***NURSING ALERT EARLY DECELERATION indicates fetal head compression; reflects mirror image in the monitor, NO treatment required LATE DECELERATION indicates placental insufficiency; reflects reverse mirror image in the monitor, administer Oxygen VARIABLE DECELERATION indicates cord compression; reflects U and W shape image in the monitor, change the patient position to left lateral recumbent and administer Oxygen 125 NURSING CARE DURING PREGNANCY 126 NURSING CARE DURING PREGNANCY NON STRESS TEST – assesses fetal activity and well being; a pregnant woman in her 3rd trimester lies down with 2 belts around the belly, a transducer (external FHR monitor) is attached to the belt. ***NURSING ALERT REACTIVE TEST – acceleration of fetal heart rate of more than 15 beats per minute above baseline FHR lasting for 15 seconds or more NON – REACTIVE TEST – acceleration of FHR of less than 15 beats pre minute above baseline FHR. May indicate fetal jeopardy 127 NURSING CARE DURING PREGNANCY PELVIC ULTRASOUND – detects abnormalities of the organs in the abdomen ***NURSING ALERT Increased fluid intake 30 mins prior to procedure in order to distend the bladder to promote organ visualization; patient needs further teaching if she voids prior to procedure 128 NURSING CARE DURING PREGNANCY PERCUTANEOUS UMBILICAL CORD BLOOD SAMPLING (PUBS, CORDOCENTESIS, FUNICENTESIS) – removal of blood from the umbilical vein using an amniocentesis technique ***NURSING ALERT RhoGam is given to Rh negative women to prevent sensitization, since there is a possibility that the fetal blood could enter the maternal circulation. The fetus is monitored by non – stress test before and after the procedure 129 NURSING CARE DURING PREGNANCY PELVIC EXAM PAPANICOLAOU SMEAR – taken from the endocervix at a 1st prenatal visit to be certain if a precancerous or cancerous condition of the uterine cervix, vulva, or vagina is not present. 130