Processes of Birth Ch 12
OB Exam 2
Terms
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- Maternal factors influencing onset of labor
- Relaxin released, pressure on cervix, uterine muscle stretching, progesterone decrease, estrogen increase
- Fetal factors influencing onset of labor
- Prostaglandin production/secretion, cortisol release, placental aging.
- Signs of impending labor
- Lightening, increased clear vaginal discharge, increased energy, GI symptoms (loose stools), cervical softening, bloody show, ROM, lower back pain (in waves), 1-3 lb. wt loss, uterine contractions.
- 5 P's affecting labor
- Power (contractions), Passenger, Passageway, Position, Psychology
- Primary powers
- uterine contractions in 1st stage of labor (onset to full dilation)
- Secondary powers
- bearing down during the 2nd stage of labor (full dilation to birth, aka the pushing stage)
- Duration of contractions
- from the beginning of a contraction to the end (in seconds). aka, how long the contraction lasts.
- Frequency of contractions
- From the beginning of one contraction to the beginning of the next. "they're beginning so frequently!"
- Intensity of contractions
- STRENGTH of contractions Mild = nose or < 40 mmHg, moderate = chin or 40-70, strong = forehead or > 70.
- Resting tone (r/t contractions)
- Tension in the uterine muscle between contractions
- Interval (r/t contractions)
- Time of uterine relaxation between the end of one contraction and beginning of the next. Time of most O2, nutrient, waste exchange w/placenta.
- Effacement
- thinning and shortening of the cervix. Usually thinner in a primip. Cervix merges with the thinning lower uterus.
- Dilation
- opening of the cervix to 10 cm during labor. with 10 cm dilation, cervix usually not palpable. cervix is pulled upward as fetus is pushed downward.
- Fetal descent through birth canal is determined by
- Size of fetal head, fetal presentation, fetal lie, fetal attitude, fetal position
- Fetal presentation
- Cephalic (most common), breech, and shoulder. Determined by the part of the fetus that first enters the pelvis.
- Types of cephalic (head first) presentations
- Occiput/Vertex = complete flexion (most common), Military = moderate flexion, Brow = poor flexion, part way extended, Face = full extension (head back)
- Vertex/occiput (cephalic) presentation = complete flexion
- Military (cephalic) presentation = moderate flexion
- Brow (cephalic) presentation = poor flexion, partial extension.
- Face (cephalic) presentation = full extension
- Frank breech presentation
- Full breech presentation
- Footling breech presentation
- Quadrants of maternal pelvis
- Shoulder presentation
- Fetus in transverse or possibly oblique lie with the scapula as the presenting part (rare)
- Fetal lie
- Relationship of the long axis (spine) of the fetus to the long axis of the mother. Longitudinal (99% of pregnancies) or Transverse. Oblique less common.
- Fetal attitude
- flexion or extension of the fetal head
- Normal fetal attitude
- moderate flexion with chin flexed on chest & extremities flexed on abdomen. Back curved in a convex C shape.
- Fetal position
- Relationship between fixed reference point on fetal presenting part and four quadrants of mother's pelvis.
- Which fetal positions are good?
- ROA, LOA ("OA is OK"). occiput of head is in lower (anterior) part of pelvis (closest to pubic symphysis vs sacrum) facing left or right.
- Which fetal position is not good?
- posterior (occiput posterior). "OP = Oh me, oh my, my aching back." Get mother off her back.
- Fetal station
- relationship of presenting part of fetus to ischial spines of mother's pelvis.
- Fetal station numbers
- Zero (0) station is at level of ischial spines. negative = not close, makes us sad. positive (+1 to +4) is good, baby's crowning.
- Mechanisms (cardinal movements) of labor
- Engagement, Descent, Flexion, Internal Rotation, Extension, External rotation, Expulsion. "Every Darn Fool In Egypt EatsRaw Eggs"
- Engagement (mechanism of labor)
- When largest diameter of presenting part (usually the head) reaches mom's ischial spines (0 or lower). Often happens before labor in nulliparas woman.
- Descent (mechanism of labor)
- Fetal presenting part moving downward through the true pelvis. Accompanies all other mechanisms of labor.
- Flexion (mechanism of labor)
- Fetal head moving down/forward. Presents the smallest head diameters to align with the smallest diameters of the midpelvis.
- Internal rotation (mechanism of labor)
- fetal head turns allowing the largest fetal head diameter to align with the largest diameter of the maternal pelvis.
- Extension (mechanism of labor)
- fetal head moves back (facing toward mom's rectum) as neck pivots on inner margin of symphysis pubis, allowing the head to align with the curves of the pelvic outlet.
- External Rotation
- fetal head turns aligning the head with the shoulders after expulsion.
- Expulsion
- delivery of the fetal shoulders and body