NUR 403 Spring 2025 Ch 13 Labor and birth process PDF

Chapter 13 Labor and Birth Processes Oonagh C. O’Reilly MSN, RN, WHNP-BC OBJECTIVES 1. Explain the five major factors that affect the labor process. 2. Describe the anatomic structure of the bony pelvis. 3. Recognize the normal measurements of the diameters of the pelvic inlet, cavity, and outle...

Chapter 13 Labor and Birth Processes Oonagh C. O’Reilly MSN, RN, WHNP-BC OBJECTIVES 1. Explain the five major factors that affect the labor process. 2. Describe the anatomic structure of the bony pelvis. 3. Recognize the normal measurements of the diameters of the pelvic inlet, cavity, and outlet. 4. Explain the significance of the size and position of the fetal head during labor and birth. 5. Summarize the cardinal movements of the mechanism of labor for a vertex presentation. 6. Examine the maternal anatomic and physiologic adaptations to labor. 7. Describe factors thought to contribute to the onset of labor. 8. Describe fetal adaptations to labor.  At least five factors affect process of labor and birth. Five P’s: Factors Passenger (fetus and placenta) Affecting Passageway (birth canal) Powers (contractions) Labor Position of mother Psychologic response 3 Factors Affecting Labor Passenger Size of fetal head Fetal presentation- part of the fetus that enters the pelvic inlet Fetal lie- spine to spine Fetal attitude- relation of the fetal body parts to one another- normal is called general flexion Fetal position- presenting part (occiput, sacrum, chin etc) 96%- cephalic head 1st 3% - breech or shoulder 4  fontanels Posterior (back)- triangular shaped- closes 6-8 weeks after birth Anterior (front) – diamond shaped- closes by 18 months All Elsevier items and derived items © 2014, 2010, 2006, 2002, Mosby, Inc., an imprint of Elsevier Inc. 5 6 7 8 Station is the relationship of the presenting fetal part to the ischial spine 9  Passageway Factors Passageway, or birth canal, is composed of: Affecting Bony pelvis- formed by the fusion of the ilium, Labor ischium, pubis and sacral bones. 4 basic types of pelvis Gynecoid- classic female pelvis Android- male pelvis Anthropoid- resembling anthropoid apes Platypelloid- flat pelvis Cervix Pelvic floor muscles Vagina Introitus (external opening to the vagina) 10 12  Powers Factors Primary powers- involuntary Effacement- shortening and thinning of the Affecting cervix / measured in %, 0-100 Dilation- the widening of the cervix/ Labor measured in cm./ 0-10 Ferguson reflex- ( sensation to bear down) Secondary powers Bearing-down efforts 13 All Elsevier items and derived items © 2014, 2010, 2006, 2002, Mosby, Inc., an imprint of Elsevier Inc. 14 All Elsevier items and derived items © 2014, 2010, 2006, 2002, Mosby, Inc., an imprint of Elsevier Inc. 15 https://www.youtube.com/watch?v=URy EZusnjBI  Factors Position of laboring woman Position affects woman’s anatomic and physiologic Affecting adaptations to labor Frequent changes in position Labor Relieve fatigue Increase comfort Improve circulation Laboring woman should be encouraged to find positions most comfortable to her More in chapter 16 17  Labor: process of moving fetus, placenta, and membranes out of uterus and through birth canal Process of Labor Various changes take place in woman’s reproductive system in days and weeks before labor begins 18 Stages of labor**** 1st– onset of regular uterine contractions -> full dilation of the cervix- (varies the most in length) Latent- the fetus continues to descend passively through the birth canal and rotate to an anterior position as a result of ongoing uterine contractions 2nd stage cervix is fully dilated - > the birth of the fetus Active pushing- a strong urge to bear down as the presenting part of the fetus descends and presses on the stretch receptors of the pelvic floor 3rd stage- fetus -> placenta delivered 4th stage about 2 hours AFTER the placenta is delivered 19 Process of Labor Signs preceding labor Onset of labor Lightening or Onset of true labor dropping- Changes in: ~ 2 weeks before maternal uterus term cervix Bloody show- mucus pituitary gland plug 21 Process of Labor Mechanism of labor Seven cardinal movements of mechanism of labor that occur in vertex presentation Engagement- (asynclitism) when the head passes the pelvic inlet Descent- the progress of the presenting part – it depends on a least 4 forces Pressure from amniotic fluid Direct pressure from contractions of fundus on fetus Force of the contraction Extension and straightening of the fetal body Flexion- when the descending head meets resistance from the cervix, pelvic wall or pelvic floor Internal rotation Extension External rotation – after the head is born/ as the shoulders engage and descend Expulsion (birth) 22 Cardinal movements of the mechanism of labor 7 Cardinal Movements – Mnemonic Every- Engagement Day- Decent Fine- Flexion Infants- Internal Rotation Enter- Extension Eager- External rotation and Excited- Expulsion 23  Physiologic Adaptation to Labor Fetal adaptation These changes occur in: Fetal heart rate - average 140 beats per minute ranges 110-160 Fetal circulation- can be affected by many factors (maternal position, contractions) Fetal respiration- changes stimulate chemoreceptors in the aorta and carotid bodies to prepare the fetus for respirations 24  Physiologic Adaptation to Labor Maternal adaptation (Box 13-2) Subjective and objective symptoms Cardiovascular changes- output peaks about 10-30 minutes after delivery, maternal circulating blood volume increases temporarily during contractions, BP increases during contraction and return to baseline in between. Respiratory changes- increased respiratory rate Renal changes- voiding may be difficult- due to edema, discomfort, analgesia, trace, +1 protein is normal because of muscle breakdown Integumentary changes- stretching of the vaginal introitus. Musculoskeletal changes- diaphoresis, fatigue Neurologic changes- euphoric, amnesia, Gastrointestinal changes- decreased motility and absorption nausea and belching may occur Endocrine changes- Decrease in Progesterone, blood glucose levels, Increase in estrogen, prostaglandins, oxytocin and metabolism 25 26