1. Normal Labor and Delivery
Barbara M. O’Brien, M.D.
Maternal Fetal Medicine and Genetics 1

2. Normal Labor and Delivery
Definition of labor: uterine contractions that cause cervical change
term pregnancy: weeks
preterm: <37 weeks
Postdates pregnancy: >42 weeks 21

3. Stages of labor
First Stage-- stage of cervical effacement and dilation
Begins when uterine contractions of sufficient frequency, intensity, and duration are attained to bring about effacement and progressive dilation of the cervix
Ends when the cervix s fully dilated (10 cm) to allow passage of the fetal head 22

4. First Stage of Labor

5. Stages of labor
Second stage of labor-- stage of expulsion of the fetus
begins when dilatation of the cervix is complete and ends with delivery of the fetus 23

6. Second Stage of Labor

7. Stages of labor
Third stage of labor-- stage of separation of separation and expulsion of placenta
begins immediately after delivery of the fetus and ends with delivery of the placenta and fetal membranes 24

8. Third Stage of Labor

9. Divisions of First Stage of Labor
Divides 1st stage into latent and active phase:
latent phase: onset of labor is defined according to Friedman as the point at which the mother perceives regular contractions
regular ctx take place along with cervical softening and effacement
prolonged latent phase: defined as greater than 20 hours in a nullipara and greater than 14 hours in a parous woman

10. Divisions of First Stage of Labor
Active phase:
cervical dilation rate of 1.2 cm/hr for nulliparas and 1.5 cm/hr for parous women
These rates of cervical dilation do not start at a specific dilatation
cervical dilation of 3 or 4 cm or more, in the presence of uterine contractions can be taken to reliably represent the threshold for active labor
nullipara on average dilate 1.2 cm/hour and multips on average dilate 1.5 cm/hour (minimum)

11. Mechanisms of Normal Labor
Fetal orientation is described with respect to fetal lie, presentation, attitude, and position
These can be established clinically by abdominal palpation, vaginal exam, or by U/S
Fetal lie: the lie is the relation of the long axis of the fetus to the mother and is either longitudinal or transverse

12. Mechanisms of Normal Labor
Fetal presentation: the presenting part is the portion of the body of the fetus that is either foremost within the birth canal or is in closest proximity to it.
In longitudinal lies, the presenting part is the fetal head or breech
In transverse lies, the presenting part is the shoulder

13. Mechanisms of Normal Labor
Cephalic presentation:
Classified according to the relation of the head to the body of the fetus
Breech presentation:
frank breech: when thighs are flexed and legs are extended over the anterior surfaces of the body
complete breech:if thighs are flexed on abdomen and legs upon thighs
incomplete or footling: if one or both feet, or one or both knees, are lowermost

14. Types of Breech Presentations

15. Mechanisms of Normal Labor
Frequency of Various Positions at term:
Vertex: 96%
Breech 3.5%
Face: 0.3%
Shoulder: 0.4%
Diagnosis of Fetal Presentation and Position:
Abdominal Palpation/Leopold Maneuvers

16. Mechanisms of Normal Labor
Cardinal Movements of Labor:
Engagement: BPD passes through the pelvis inlet
Descent
Flexion: chin is brought into contact with fetal thorax
Internal Rotation: turning of the head such that the occiput moves towards the pubic symphysis or posteriorly
extension: of the head (or breech) so it can pass
External rotation: head undergoes restitution
expulsion: delivery of the anterior and posterior shoulders

17. Identification of Labor
Uterine contraction that cause cervical change
Vaginal Exam:
note dilation, effacement, consistency, station
Ruptured membranes?
Fern, pool, nitrazine test
sterile speculum
infrequent vaginal exams if SROM

18. Maternal Monitoring and Management during Labor
Maternal Vital Signs every 4 hours
if temperature: chorioamnionitis: need to treat with antibiotics that will cover gram negative and anaerobes (ampicillin and gentamicin
Group B strep is a big offender and we have moved to universal screening
Oral Intake: food should be withheld during active labor
Analgesia

19. Spontaneous Delivery Spontaneous Delivery Delivery of the head
Episiotomy vs. no episiotomy
clearing the nasopharynx
check for a nuchal cord
Delivery of the shoulders
clamping the cord
Watchful waiting for the placenta unless there is unusual bleeding
give oxytocin
Do any vaginal repair as needed