11/19/23, 8:33 AM Exam2studyguide - Summary Maternity and Pediatric Nursing
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OB Ex am 2
Labor and Childbirth
Initiation of Labor p g. 456
It is believed tha t labor is influenced by: uterine s tretch from the fet us and amniotic fluid volume, pr ogest erone withdr awal to est rogen dominance, incr ease oxyt ocin sensitivity , and increased r elease of pros taglandins
Estrogen to pro gester one ra tio
oDuring the last trim ester estr ogen increases a nd progester one decreases
The number of o xytocin receptor s in the uterus incr eases at the end of preg nancy
Increased le vels of estr ogen also lead to incr eased sensitivity to o xytocin
With increa sing o xytocin le vels in the maternal blood a long with incr easing fet al cortisol levels tha t synthes ize prost aglandins, uterine concentr ations ar e initiated Oxytocin also aids in s timulating pros taglandin syn thesis
Pros taglandins lead to additional c ontractions, cervica l softening, gap junction induction, and my ometrial sensitiza tion leading to prog ressive cervical dila tion Uterine co ntractions ha ve two main functions: d ilate the cervix and to push the f etus through th e birth canal Signs of Approachin g Labor pg. 456
Light ening occur s when the fet al presenting part b egins to descend into the true pe lvis oThe uterus lo wers and moves in to a more an terior position oThe woman will usually notice her br eathing becomes much easie r and ther e is decreased g astric r eflux
oShe ma y compla in of increa sed pelvic pressure, leg cr amping, dependent edema in the lower legs, l ow back discomfort , increase in vag inal discharg e and urination
oIn primipara s, lightening can occur 2 week s or more bef ore labor beings and in multipara s, it may not occur until labor
Braxton Hicks Contr actions may be e xperienced throughout the pr egnancy
oFelt as tigh tening or pulling sensation on t op of the ute rus oOccur primarily in abdomen and gr oin and gradually spr ead downward be fore relaxing
oIrreg ular contr actions that can be decr eased by walk ing, voiding, eating, increasing fluid inta ke, or chang ing position oUsually last about 30 sec onds but can last up to 2 minut es
oAs birth gets close r, the uterus bec omes more sensitive t o oxytocin a nd the frequency and in tensity of these contr actions incr eases
oIf the cont ractions last long er than 30 secs and occur more than 4-6x/hr , the woma n should cont act her HCP so she can be ev aluated f or preterm labo r
Backa che
Bloody show
oAt the onset of labor or bef ore, the mucous plug tha t fills the cervical c anal is expe lled as a result of c ervical softening and incr eased pressur e of the presenting part 11/19/23, 8:33 AM Exam2studyguide - Summary Maternity and Pediatric Nursing
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oThese ruptur ed capillaries release a sma ll amount of blood tha t mixes with mucus resulting in the pin k tinged secr etions known as the bloody show
Spont aneous Ruptur e of Membranes
oRupture o f membr anes with loss of amniotic fluid prior to onset of labor
prema ture ruptur e of membr anes (PROM)
oThe majority of women wil l begin labor within 24 hour s
oThe ruptur e can result in either a sudden gush or a s teady leakag e of amniotic fluid oA continuous supply of a mniotic i s produced even though some is lost oAfter the amniotic sa c has ruptur ed, the barrier to inf ection is gone and ascending infection is possible oThere is a lso a danger of c ord prolapse i f engagemen t has not occurred
Increased Ener gy Level
oSome women ha ve a sudden increa se in energ y befor e labor oSometimes this is r eferr ed to as nesting because the mothe r will use this time t o prepar e for the baby and sp end time with other children
oUsually occurs 24 -48 hours bef ore the onset of labo r
oThought to be t he result of an increase in ep inephrine r eleased caused by decreased prog ester one Weight loss loses 1-3lbs
True vs. False Labo r pg. 457
False labor irregular uterine c ontractions ar e felt but t he cervix is not aff ected
oFalse labor , prodro mal labor , Braxt on Hicks True labor contr actions occurring at r egular intervals tha t increase in fr equency , dura tion,
and int ensity
oBring about progr essive cervical dilatio n and effacement Exampl e: if a woma n comes in and she goe s from 2cm to 3 cm then back to 2cm a nd sta ys that w ay for hours, you would send her home beca use it’s not progr essing
Cervical Dilata tions and E ffacement
Dilat ation is the opening of the cervix
Effacemen t is the thinning of the cer vix 11/19/23, 8:33 AM Exam2studyguide - Summary Maternity and Pediatric Nursing
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Theories of Onset of Labor
Oxytocin pr oduction
Pros taglandin Estrogen stimulation
Fetal influences
Other s
“P’s” of Labor pg. 458
Passagew ay (birth cana l)
Passenger (f etus and placent a)
Power s (contr actions)
Position (mat ernal)
Psychological response Passag ewa y pg. 458
Have to mak e sure the baby c an come out
The birth passagew ay is the r oute through which the f etus must travel t o be born vaginally
The passagew ay wa y consists of the ma ternal pelvis and soft tissues
The pelvis is the most import ant and it is typically a ssessed and measur ed during the first trimest er to identify an y abnormalities that might hinder v aginal birth
Rela xin and estrog en cause the connective tissu es to become mor e relax ed and elastic and cause the joints t o be more fle xible to prepar e the mother ’s pelvis for birth
Bony Pelvis
The mat ernal bony pelvis can be divided in to the true and fals e portions
The fa lse part is the upper part and the true p elvis is the bon y passage through which the fetus must tra vel 11/19/23, 8:33 AM Exam2studyguide - Summary Maternity and Pediatric Nursing
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oMade up of: the inlet, the mid-pelv is (cavity), and the outlet
To ensure the adequacy o f the pelvic outlet f or vaginal birth, t hese measur ements are assessed:
oDiagonal conjug ate of th e inlet (dis tance between the an terior surfa ce of the sacral prominen ce and the ant erior surface of the inf erior margin of the sy mphysis pubis)
oTrans verse or ischial tuber osity diameter of the outlet (distance at t he medial and lowes t aspect of the ischial tuberosities, a t the lev el of the anus, a known hand span or clenched-fis t measurement is g enerally used to o btain this measuremen t)
oTrue or obste tric conjuga te (dista nce estimated f rom the measur ement of the diagonal conjug ate; 1.5cm is subtr acted fr om the diagonal conjug ate measur ement)
If the diagonal con jugate measures a t least 11.5cm and the true or ob stetric con jugate measures 10cm o f mor e (1.5cm less than diagonal conjug ate, or about 10cm), then the pelvis is larg e enough for v aginal birth of what would be cons idered a normal siz ed newborn
Pelvic Shape
The shape is a determ ining factor of a woman’ s pelvis in addition to siz e
Each plane of t he pel vis has a shape, which is de fined by the anterior -post erior and transver se diameter s
Gynec oid Pelvis
oConsidered the true f emale pelvis 40% of women
oVaginal birth is most f avor able with this type because the inlet is r ound and the outlet is r oomy
oOptimal diamet ers in all 3 planes of the pelvis
oAllows early a nd complet e fet al internal r otation during labor a nd the sacrum is long,
producing a deep pe lvis oVaginal birth is more f avor able with the pelvic shape compar ed with android or platypelloid shape
Anthr opoid Pelvis
oMost commo n in men and mos t common in no n-white wo men 25% of women
oThe pelvic inlet is ov al Android P elvis
oConsidered the male sha ped pelvis and i s char acteriz ed by a funnel shape 20% of
women
oThe pelvis inlet is heart shaped and the pos terior segments ar e reduced in all pelvic planes
oDescent of the f etal head in to the pelvis is slow and f ailure of f etus to ro tate is common oPrognosis is poor and usually leads to c-s ection Platypelloid (fla t) Pelvis
oLeast com mon type 3% incidence
oPelvic cavity is shallow but widens at the pelv ic outlet, making it difficult for the f etus
to descend thr ough the mid-pelvis
oLabor prognosis is poor with arr est in the inlet occurring fr equently usually
requir e c-section