Chapter 7 Flashcards
how does the uterus grow during pregnancy?
- starts at 70g w/ capacity of 10 mL and by term, it weighs 1100-1200 g and holds 5 L
- growth is the result of hyperplasia and hypertrophy
- early in pregnancy: hyperplasia occurs due to estrogen and growth factors
- late in pregnancy: hypertrophy occurs as muscle fibers stretch to hold fetus
- the muscle also inc in strength as amount of elastic tissue inc and muscles in the myometrium expand in length and width
- the wall of the uterus gradually thins out
pattern of uterine growth
- the growth helps confirm the EDD
- by 12 weeks: can palpate uterus above symphysis pubis
- by 16 weeks: fundus midway b/w symphysis pubis and umbilicus
- by 20 weeks: fundus at the umbilicus
- by 36 weeks: fundus at the xiphoid process
- pushes against the diaphragm–>shortness of breath
- by 40 weeks: lightening occurs, and uterus sinks to a slightly lower level
- makes breathing easier
contractility and uterine blood flow throughout pregnancy
- throughout pregnancy, uterus undergoes Braxton Hicks contractions
- these are infrequent and during first 2 trimesters, they aren’t felt
- later in pregnancy, they may be more frequent and uncomfortable
- as uterus enlarges, number and size of blood vessels inc
- delivery of materials needed for fetal growth depends on adequate perfusion
- by term, 1200 mL of blood per min reach the placenta
- maternal blood carried by myometrial arteries–>intervillous spaces–>O2 and nutrients transferred to chorionic villi–>fetus
how does the cervix change during pregnancy?
- water content and vascularity of the cervix inc
-
hyperemia (congestion w/ blood) occurs due to inc estrogen and results in bluish purple color that extends to vagina and labia
- this discoloration is called Chadwick sign (early sign of pregnancy)
- Goodell sign: cervical softening
- glandular walls bcome thin and widely spaced and these spaces fill with mucous which becomes the mucus plus: filled with lots of immunoglobulins and blocks the ascent of bacteria
how does the vagina and vulva change during pregnancy?
- inc vascularity causes the vaginal walls to appear bluish purpple
- connective tissue softens and allows the vagina to distend
- vaginal mucosa thickens and vaginal rugae become prominent
- vaginal cells contain inc amounts of glycogen which causes rapid sloughing and inc thick, white, vaginal discharge
- vaginal pH is acidic from inc production of lactic acid which helps prevent bacterial growth
- but the glycogen rich environment sometimes allows growth of fungi, so yeast infections are common
- inc vascularity can lead to heightened sexual interest
how do the ovaries change during pregnancy?
- progesterone must be released to maintain pregnancy to suppress uterine contractions and prevent tissue rejection of the fetus
- after conception, the corpus luteum secretes progesterone during first 6-7 weeks
- b/w 6-10 weeks, placenta starts taking over and the corpus luteum regresses
- ovulation ceases b/c of inc estrogen and progesterone which suppress LH and FSH
how do the breasts change during pregnancy?
- estrogen stimulates the growth of mammary ductal tissue
- progesterone stimulates the growth of lobes, lobules, and alveoli
- breasts become highly vascular
- striae may develop if breast size inc drastically
- nipples inc in size and become darker and more erect
- areolae become larger and more pigmented
- tubercles of Montgomery (sebaceous glands) become more prominent and secrete colostrum as early as 16 weeks of gestation
how does the heart change during pregnancy?
- cardiac changes are minor and reverse after childbirth
- muscles of the heart enlarge during the first trimester
- heart is pushed up and to the left as the uterus pushes up into diaphragm
- some heart changes may be altered starting during 12-20 weeks and continue for 2-4 weeks after childbirth
- most common includes splitting of the first heart sound or a systolic murmur best heard at the left sternal boarder
blood volume during pregnancy
- inc begins by 6 weeks gestation
- reaches an average of 30-45% during pregnancy
plasma volume during pregnancy
- inc from 6-8 weeks until 32 weeks gestation
- 40-60% greater than in non-pregnant women
- may be due to vasodilation from nitric oxide, and estrogen, progesterone, and PG stimulation of RAAS
- inc volume is needed to:
- transport nutrients and O2 to the placenta
- meet the demands of expanded maternal tissue
- provide a reserve to protect the pregnant women from blood loss
red blood cell volume during pregnancy
- RBC inc 20 to 30% above prepregnancy values
- although both RBC volume and plasma volume expand, the inc in plasma vol is more pronounced and occurs earlier
- this resulting dilution of RBC mass causes a decline in maternal H&H which causes physiologic anemia of pregnancy
- may be protective against forming clots
- this resulting dilution of RBC mass causes a decline in maternal H&H which causes physiologic anemia of pregnancy
- need frequent lab tests to distinguish b/w physiologic anemia and true anemia
- iron deficiency anemia can occur if Hgb is less than 11 in 1st and 3rd trimesters or 10.5 in 2nd
cardiac output and systemic vascular resistance during pregnancy
- expanded blood volume of pregnancy results in an inc in CO (half the rise in CO occurs in first 8 weeks)
- due to an inc in SV and HR (inc by 15-20 bpm by 32 weeks)
- CO is hghest when women is lying on her side and is lower in the standing and supine positions
- vascular resistance falls during pregnancy b/c
- vasodilation resulting from effects of progesterone and PGs
- addition of uteroplacental unit so greater area for circulation
- inc heat production–>vasodilation
- dec sensitivity to Ang II
- endothelial prostacyclin and nitric oxide
blood pressure during pregnancy
- BP is affected by position, so need to document her position when taking BP
- SBP remains largeley unchanged if measured when sitting or standing
- DBP shows a dec (10-15) that is greatest by 24-32 weeks and returns to normal at gestation
-
supine hypotension: weight of pregnant uterus occludes vena cava and aorta and diminishes return of blood, so CO is reduced
- some women may develop lightheadedness, dizziness, nausea, syncope
- may also cause fetal hypoxia if supine too long
- turn to lateral recombent to correct
5 changes to blood flow during pregnancy
- blood flow is altered to include the uteroplacental unit
- renal plasma flow inc up to 30% to remove inc waste from fetus and mother
- woman’s skin requires inc circulation to dissipate heat generated by inc metabolism during pregnancy
- blood flow to the breasts inc resulting in engorgement and dilated veins
- weight of expanding uterus on IVC and iliac veins can partially obstruct blood return from veins in legs
- blood can pool and cause venous distention
- can lead to varicose veins or hemorrhoids
blood components during pregnancy
- iron absorption inc but not always enough in diet, so need supplementation
- leukocytes inc to as high as 15000
- postpartum can reach 25000-30000
- pregnancy is a hypercoaguable state b/c of an inc in factors that favor clotting, like fibrinogen, factors 7, 8, 9, and 10
- inc the ability to form clots
- fibrinolytic activity dec
- offers some protection from hemorrhage during childbirth
3 major respiratory changes during pregnancy
- inc oxygen consumption: most is used by the fetus, uterus, and placenta
- progesterone causes the woman to hyperventilate slightly by breathing more deeply
- hormonal factors:
- progesterone helps dec airway resistance and inc the sensitivity of the respiratory center in the medulla oblongata to CO2
- estrogen causes inc vascularity of the mucous membranes
- edema and hyperemia develop which may cause nasal stuffiness, epistaxis, deepening voice
- physical effects of the enlarging uterus:
- enlarging uterus lift diaphragm, ribs flare, substernal angle widens, transverse diameter expands
- all results from the hormone relaxin
- breathing becomes more thoracic rather than abdominal
- enlarging uterus lift diaphragm, ribs flare, substernal angle widens, transverse diameter expands
GI system during pregnancy
- appetite inc
- mouth:
- elevated levels of estrogen cause hyperemia of the mouth and gums and may lead to gingivitis and bleeding gums
- some women experience ptyalism which is excessive saliva
- lower esophagel sphincter tone decwhich may cause heartburn (pyrosis)
- elevated levels of progesterone relax the tone and motility of the GI tract
- gastric acidity dec during the first 2 trimesters and inc during the 3rd
- emptying time of the intestines inc which allows inc nutrient absorption
- may cause bloating and abdominal distention
- also may cause constipation due to more water reabsorption in lg intestine
- enlarged liver: alkaline phosphatase rises, albumin falls (likely due to hemodilution)
- gallbladder becomes hypotonic: bile thickens and inc risk of gallstones
bladder in the pregnant woman
- frequency and urgency of urination inc
- if occurs with pain: may indicate infection
- hormonal influences, inc blood volume, and changes in renal blood flow and GFR may cause inc urinary frequency
- stress and urge incontinence may occur
- bladder capacity doubles by term and tone is decreased in response to progesterone
- nocturia is common
- bladder walls become hypertrophied due to estrogen
- dec drainage of blood from base of the bladder results in edema dn renders the area susceptible to trauma during childbirth
kidneys and ureters during pregnancy
- kidneys change in size and shape due to dilation of the renal pelvis and ureters
- dilation begins during 2nd month
- ureters become elongated and are compressed b/w enlarging uterus
- flow of urine is partially obstructed and this stasis can allow time for bacteria to grow
- renal blood flow inc due to inc plasma volume and CO and is highest when woman lying on her left side
- GFR inc due to higher renal blood flow
- need this to excrete extra waste from fetus
- glucosuria is common during pregnancy
- urine output inc and mild proteinura is common
- due to inc GFR: serum Cr and BUN dec
skin during pregnancy
- circulation to the skin inc to dissipate excess heat
- pregnant women feel warmer and perspire more
- accelerated activity of sebaceous glands–>acne
- inc pigmentation from inc estrogen, progesterone, and melanocyte stimulating hormone
- may cause melasma (brownish patches on forehead, cheeks, nose) or linea nigra
- moles, freckles, and areolae darken
- blood vessels dilate and proliferate which is due to estrogen
- angiomas may occur on areas exposed to the sun, palmar erythema may occur
connective tissue, hair and nails during pregnancy
- striae gravidarum (stretch marks) may occur: fade to silvery lines after pregnancy
- laser therapy may be able to be used after pregnancy
- b/c fewer follicles are in the resting phase, hair grows more rapidly and less hair falls out during pregnancy
- more hair loss can occur after childbirth, but returns to normal in 6-12 mos
- nails may become brittle or softer
- may grow faster or break more easily
musculoskeletal system during pregnancy
- fetal demands for calcium inc, so absorption from intestine doubles–>only 28-30 g are transferred to fetus and this does not deplete maternal bone density
- musculoskeletal changes are progressive
- early in pregnancy: relaxin and progesterone initiate relaxation of the ligament
- at 28-30 weeks: pelvic symphysis separates
- inc mobility of pelvis causes waddling gait
- during 3rd trimester, uterus inc in size and she must lean back to maintain balance
- can create lordosis and backache
- abdominal wall muscles may be stretched byond capacity and cause diastasis recti
who is at risk for diastasis recti?
–Previous abdominal surgery
–More than one pregnancy
–Multiples in pregnancy
–Increased weight gain in pregnancy
–Long pushing phase of labor
–Chronic coughing
–Chronic constipation
–Caucasian ethnicity
–Petite frame
pituitary gland during pregnancy
- anterior pituitary inc in size
- prolactin levels inc to prepare lactation
- FSH and LH are suppressed by progesterone and estrogen
- posterior pituitary releases oxytocin which stimulates contractions
- progesterone inhibits this early in pregnancy
- estrigeb causes a gradual rise in oxytocin receptors in the uterus to inc contractions near term
- oxytocin also role in preventing postpartum hemorrhage