Chapter 25 A Formation of gametes: ovum and spermatozoon are formed by meiosis; each have one set of 23 chromosomes; other body cells have two sets (46 chromosomes, 23 pairs) B Chromosomes: carry sets of matching genes (alleles); one may be dominant, the other recessive, or have blending expressions 1. Females have two X chromosomes; males have one X and one Y chromosome 2. Ovum has one X chromosome; sperm have either an X or a Y chromosome 3. X-bearing sperm that fertilizes an ovum results in a female; Y-bearing sperm that fertilizes an ovum results in a male 1. Sex-linked genes: carried on X chromosome are always expressed in the male, even if recessive (e.g., hemophilia, color blindness) 2. Multiple genes: may combine to produce cumulative effects (e.g., degree of pigmentation, height) 3. Multiple alleles: influence human traits (e.g., blood types, eye color) 1. Additional sex chromosomes produce individuals with genetic abnormalities (e.g., Turner syndrome; Klinefelter syndrome) 2. Translocation of chromosomes (e.g., trisomy 21 [Down syndrome]) 1. Occurs about 24 hours after ovulation when sperm enters ovum 2. Zygote forms; chromosome number restored to two sets (46 chromosomes) G Cleavage: rapid mitotic division of zygote produces morula that divides to form blastocyst H Implantation: blastocyst implants in uterine wall 7 to 8 days after fertilization 1. Dual origin: maternal and embryonic a. Chorion: becomes major part of placenta; forms chorionic villi (fingerlike projections growing into uterine endometrium) b. Amnion sac: surrounds embryo; contains amniotic fluid at 46 to 48 days gestation a. Site for interchange of food, gases, and wastes between mother and embryo/fetus b. Produces estrogens, progesterone, adrenocorticotropic hormone [ACTH], human chorionic gonadotropin [hCG], and human placental lactogen [hPL]) c. Protective barrier against harmful effects of some drugs and microorganisms 1. Conceptus: embryo during first 2 months; fetus thereafter 2. First 8 weeks: organogenesis (rapid growth and development of organs); interference can cause irreparable fetal damage; preconception counseling includes avoidance of alcohol, tobacco, illegal, and over-the-counter drugs 3. At 14 days: heart begins to beat; brain, early spinal cord, and muscle segments present 4. At 30 days: embryo 5. At 31 to 36 days: both arms and legs have digits but may be webbed; 46 to 48 days: cartilage in upper arms replaced by first bone cells 6. End of 8 weeks: organ systems and external structures are recognizable 1. At 9 weeks: genitalia begin to differentiate; fully differentiated by 12 weeks 2. At 12 weeks: moves, swallows, respiratory movements present; weighs 28 g (1 oz); fetal heart audible with Doptone (fetal heart rate (FHR) 110 to 160 beats/min); chorionic villi sampling at 10 to 12 weeks 3. At 16 to 20 weeks: fetal movements felt by mother (quickening); weighs 170 g (6 oz); 20 to 25 cm (8 to 10 inches) in length; 200 mL of amniotic fluid enables amniocentesis at 14 to 16 weeks; vernix and lanugo cover and protect fetus 4. At 20 to 24 weeks: hair growth on head, eyelashes, and brow; skeleton hardens; eyelids closed; weighs 0.45 kg (1 lb); 30.5 cm (12 inches) in length; respiratory movements become more regular 5. At 24 to 28 weeks: eyelids open; amniotic fluid increases; weighs 0.5 kg ( 6. At 28 to 32 weeks: brown fat begins to deposit; weighs 0.5 to 0.7 kg (1 to 7. At 32 to 36 weeks: stores protein for extrauterine life; gains 1.8 kg (4 lb) 8. At 36 to 40 weeks: lanugo disappears; vernix present, particularly in creases; nails extend; visible mammary glands; testes palpable in scrotum; weighs 3 to 3.6 kg (6 lb 10 oz to 7 lb 15 oz) but varies; full-term birth is 38 to 40 weeks 9. Fetal circulation: contains mixed blood with low oxygenation; 30% to 70% oxygen saturation A Affirmation and confirmation of pregnancy 1. Presumptive signs: subjective (may be indicative of illness); amenorrhea; fatigue; nausea and vomiting; breast changes; urinary frequency; darkening of pigmentation on face, breasts, and abdomen; quickening (feeling of movement at about 16 to 20 weeks) 2. Probable signs: objective but not definite confirmation a. Uterine changes: uterine enlargement; Hegar sign (lower uterine segment softens), Goodell sign (cervix softens) b. Vaginal change: Chadwick sign (color becomes purplish) c. Fetal outline; ballottement d. Pregnancy tests: urine and blood detects human chorionic gonadotropin (hCG) 3. Positive signs: confirmation a. Fetal heartbeat: heard with fetoscope, Doppler b. Fetal outline and movement: felt by examiner c. Ultrasonography: visualization of fetus and movement of fetal heart 4. Identification of singleton or multiple gestation (early determination vital because multiple gestation contributes to perinatal morbidity and mortality) 5. Estimating date of birth (EDB) and duration of pregnancy a. Nägele rule: count back 3 months from first day of last menstrual period and add 7 days and 1 year b. Fundal height: measurement from symphysis pubis to top of fundus; fundus rises about 1 cm per week up to 30 weeks; 20 weeks at umbilicus (McDonald rule), 36 weeks at xiphoid process c. Ultrasonography: up to 11 weeks gestational age established by crown to rump measurement (must have full bladder to move uterus into abdominal cavity for visualization; instructed to drink quart of fluid before test); 11 weeks head measurements (biparietal diameter is 9.8 cm or more at term) 1. Ambivalence about pregnancy, parenting, impact on family 3. Sexual desire may increase or decrease 4. First trimester: acceptance of biologic fact of pregnancy; acquires knowledge regarding physical, physiologic, and emotional changes of pregnancy 5. Second trimester: acceptance of growing fetus as distinct from self 6. Third trimester: preparation for birth; anxiety related to birth, newborn’s health, additional responsibilities 1. Hormones secreted by placenta a. Human chorionic gonadotropin (hCG): confirms pregnancy; maintains pregnancy; continues secretion of progesterone and estrogen from corpus luteum during first trimester; causes morning sickness; peaks at end of first trimester, then drops; high levels associated with hydatidiform mole b. Estrogen: secreted during last two trimesters; promotes vasodilation; softens cervix; helps prepare breasts for lactation; causes sodium and water retention; increased estriol levels in maternal saliva may indicate preterm labor c. Progesterone: inhibits uterine contractions; promotes smooth muscle relaxation, causing decreased GI motility and increased bladder capacity; promotes sodium loss d. Human placental lactogen (hPL) or human chorionic somatomammotropin (hCS): diabetogenic (diminished insulin efficiency); decreases maternal utilization of glucose, providing more glucose for fetal growth; affects lipid and protein metabolism; helps prepare breasts for lactation 2. Thyroid: increased secretion may mimic mild hyperthyroidism 3. Parathyroids: increased secretion affects calcium metabolism a. Cortisol: promotes carbohydrate, protein, and fat metabolism; activates gluconeogenesis to produce glucose for more energy b. Aldosterone: production increases; rennin and angiotensin II levels rise; protects against excessive sodium loss a. Anterior: enlarges; ovulatory hormones are suppressed; prolactin secreted to help prepare breasts for lactation b. Posterior: releases oxytocin, which stimulates uterine contractions that initiate labor; after birth, contracts uterus and stimulates milk ejection reflex 6. Pancreas: increases insulin production early in pregnancy 1. Ovaries: ovulation inhibited by high levels of circulating estrogen and progesterone secreted by corpus luteum 2. Uterus: circulatory, hormonal, and other changes related to fetal growth; amenorrhea resulting from continuation of corpus luteum; enlarges from 70 g to 1000 g; rises from pelvis to abdomen after first trimester; Hegar sign; Goodell sign 3. Vagina: leukorrhea from uterus; Chadwick sign; acidity increases 4. Breasts: fullness, tingling, soreness, darkened areolae, and nipples 1. Nausea and vomiting (morning sickness) during first trimester; related to human chorionic gonadotropic (hCG) hormone 2. Excessive salivation (ptyalism) 3. Gingivitis; caused by hyperemia and softening of gums; hyperacidity of oral secretions; increased vitamin C intake and regular oral hygiene relieve problem 4. Gallbladder; emptying time decreases; may precipitate gallstone formation 5. Development of food cravings; unusual cravings for clay, starch, dirt (pica); may be harmful 6. Heartburn (pyrosis): caused by delayed emptying time of stomach, reflux of gastric acid contents into esophagus, gastric irritants (e.g., coffee, tea, chocolate) 7. Hiatus hernia: risk in older, obese women or if carrying multiple fetuses 8. Constipation: caused by decreased GI motility, low fluid intake, low fiber intake, pressure of enlarged uterus on internal organs; straining on defecation may contribute to development of hemorrhoids 1. Frequency: caused by weight of uterus on bladder in early and late pregnancy 2. Increased bladder capacity: smooth muscle relaxation reduces bladder tone, increases capacity to 1500 mL 3. Dilation of renal pelvises and ureters: caused by pressure of enlarging uterus; right ureter displaced more than left 4. Flow rate: decreased, leading to retention, stasis, risk for infection 5. Lowered renal threshold: caused by glycosuria; occasional mild proteinuria 1. Blood volume: increased to meet needs of woman and fetus 2. Physiologic anemia: caused by hemodilution; blood volume increases 45% to 50% with ratio of 75% plasma and 25% RBCs; imbalance between plasma and RBCs reduces hematocrit and hemoglobin; anemia diagnosed when hemoglobin is less than 11 g/dL 3. Cardiac output: increases 30% to 50%, peaking at 28 to 32 weeks 4. Heart rate: increases 10 to 15 beats/min in latter half of pregnancy; palpitations in early months from sympathetic nervous stimulation, in later months from increased thoracic pressure caused by enlarged uterus a. Slight decrease in second trimester b. Supine hypotension (vena caval syndrome): weight of enlarged uterus compresses vena cava; blood return to heart decreases; cardiac output decreases causing lightheadedness, faintness, and palpitations (Figure 25-1: Supine hypotension) 6. Blood components: increased WBCs (from 5000/mm3 to 12,000/mm3), fibrinogen, and other clotting factors increase 7. Pelvic hyperemia and pressure of uterus on pelvic blood vessels: can cause varicose veins of legs, vulva, and perianal area 8. Peripheral edema in last 6 weeks: caused by venous stasis 9. Thrombophlebitis: heparin or low-molecular-weight heparin (enoxaparin [Lovenox]) may be administered because they do not cross placental barrier; bed rest with leg elevation prescribed 1. Oxygen consumption: increases by about 15% between 16th and 40th weeks; slight increase in vital capacity; thoracic cavity expands up to 40%, tidal volume increases causing the thoracic cavity to expand by 40% 2. Hyperventilation: caused by need to blow off increased carbon dioxide transferred from fetus 3. Nasal congestion and epistaxis: response to increased estrogen levels 4. Third trimester: pressure of enlarged uterus on diaphragm and lungs may cause dyspnea; subsides with lightening at about 38 weeks 1. Diaphoresis: caused by excretion of wastes through skin 2. Skin changes: increased melanin causes darkening of areolae, dark patches on face (melasma, formerly chloasma), linea nigra on abdomen; striae on abdomen and legs caused by skin stretching as pregnancy advances; erythematous changes on palms and face in some women 1. Ligaments and joints: soften, especially symphysis pubis and sacroiliac joint; caused by increased hormonal action of estrogens and relaxin 2. Leg cramps: caused by imbalance of calcium (hypocalcemia), pressure of gravid uterus on nerves supplying lower extremities, decrease in dietary calcium K Nutritional needs during pregnancy 1. Increased calories: meets increased basal metabolic needs (300 additional calories during second and third trimesters); spares protein for growth, promotes weight gain to support pregnancy a. Gain of 14.4 to 16 kg (25 to 35 lb); about 4 lb every month after initial 3- to 4-lb gain in first trimester b. Underweight gain more, overweight gain less; if carrying multiple fetuses gain more than recommended for one fetus c. Body mass index: helps to individualize appropriate weight gain a. Protein: provided for fetal growth demands b. Vitamins: especially folic acid to prevent anemia, neural tube defects c. Minerals: supplemental iron to prevent anemia d. Calcium: from milk and cheese to promote fetal bone and tooth development, prevent maternal bone loss 4. Fluids: 6 to 8 glasses/ day a. Based on a balanced diet; include minerals (e.g., iron, calcium, phosphorus, iodine, zinc, sodium); iodized salt provides sodium and iodine; sodium restriction is potentially dangerous because it limits interstitial fluid reserve needed if maternal blood volume decreases b. Servings of specific nutrients (1) Four dairy products: provide calcium, protein, vitamins A and D, riboflavin (2) Three (2 oz) servings of protein (3) Six or more servings of bread and cereal (4) Five servings of fruits or vegetables containing vitamin C (5) One serving of leafy, dark-green or deep-yellow vegetables (6) One serving of yellow fruit or vegetables; two servings of other vegetables or fruits a. Shrimp, salmon, pollack, catfish, canned light tuna; no more than one to two servings a week b. Albacore white tuna; no more than 6 ounces in one week c. Privately caught fish: check with local health department before eating a. Raw fish, especially shellfish; soft-scrambled eggs; foods made with raw or lightly cooked eggs b. Unpasteurized juices and milk c. Foods made from soft cheeses (e.g., brie, feta, Camembert, Roquefort, queso blanco, queso fresco, Panela) d. Raw sprouts, especially alfalfa sprouts e. Herbal supplements and teas f. Fish high in mercury (e.g., shark, swordfish, king mackerel, tilefish) g. Raw or undercooked meat, poultry, seafood, hot dogs h. Deli meats (e.g., ham, bologna): can cause food poisoning; must be reheated before eating L Pregnant adolescent nutritional needs M Nutrition and related nursing care a. Physical, cultural, economic, and psychologic needs b. Preconception; obesity or underweight; age and parity; individual needs; biologic interactions among mother, fetus, and placenta c. Parturition: weight gain (e.g., quality of gain, gain related to fetal size); severe caloric restriction and weight reduction contraindicated (increased risk to mother and fetus, especially during organogenesis) a. Date of last menstrual period b. Personal, gynecologic, family medical history; obstetric history using GTPAL system (1) Gravida: number of conceptions (2) Term births: number of births between 37 and 40 weeks’ gestation (3) Preterm births: number of births between 20 and 36 weeks’ gestation (4) Abortions: number of spontaneous or induced terminations of pregnancy before 20 weeks’ gestation (5) Living children: number of children alive at time of assessment c. Physical examination including baseline vital signs, weight d. Pelvic examination: vaginal, rectal e. Current nutritional status; dietary history f. Laboratory tests (some tests performed at subsequent visits) (1) Complete blood count; hemoglobin and hematocrit; blood type to determine ABO incompatibility; Rh factor (if indicated, antibody titer test and/or indirect Coombs test) to determine potential hemolytic condition) (2) Tuberculosis; Tay-Sachs, particularly for Jewish women; sickle cell, particularly for African-American women (3) Pap test for cancer; wet prep for bacterial vaginosis (linked to preterm labor) (4) Serologic test for syphilis, repeated at 32 weeks; cervical smears for gonorrhea and chlamydia (5) Rubella titer: titer of 1:8 considered immune (6) Cytomegalovirus, hepatitis B, HIV, parvovirus, toxoplasmosis, varicella-zoster virus (7) Herpes culture: first visit, at 36 weeks, if woman or partner has history of genital herpes (8) Alpha-fetoprotein (AFP): at 14 to 16 weeks; screening test to determine neural tube defects, Down syndrome, other congenital anomalies (9) Routine sonogram: at 18 to 20 weeks; confirms gestational age; assesses placenta, fetus, amniotic fluid (10) Chorionic villi sampling or amniocentesis: determines chromosomal or other abnormalities for women at risk (35 years or older) (11) Serum glucose level: at 26 to 28 weeks for gestational diabetes
Nursing Care of Women during Uncomplicated Pregnancy, Labor, Childbirth, and the Postpartum Period
Prenatal Period
Data Base
Development of the Embryo/Fetus
to 
inch (0.6 to 1.2 cm) in length, definite form, umbilical cord becomes visible
lb); alveolar cells of lungs produce pulmonary surfactants that minimize surface tension
lb)
Physical, Physiologic, and Emotional Changes during Pregnancy
Nursing Care during the Prenatal Period
Assessment/Analysis
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