FM Labor and Delivery

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Table Of Contents
1 FM Labor and Delivery
2 3 Stages of Labor
3 Fetal Monitoring
4 Contractions
5 Cesarean Section
6 Popular Sections

FM Labor and Delivery

  • Estimated date of confinement:
    • = 280 days after 1st day of LMP.
    • Usually go into labor w/in 2 weeks of EDC.
    • Labor > 3 weeks before is preterm. 
    • Admit to the birthing unit if membranes have ruptured or in active labor.
  • Signs to confirm rupture of membranes:
    • Amniotic fluid, pH > 6.5 with nitrazine paper (contrast normal secretions < 5.5), and ferning on air dried microscope slide.
    • Blood, semen, or vaginosis, can falsely elevate pH.
  • Rupture > 24 hours can predispose to infection.

3 Stages of Labor

  • Stage 1 = onset to full dilation of cervix.
    • Latent Phase of Stage 1
      • – contractions become stronger, longer, and more coordinated.
    • Active Phase of Stage 1
      • – > 3-4 cm of dilation, rate of dilating is maximal.
      • Contractions are strong and regular. Admit to the hospital for labor management and monitoring.
      • If no epidural, at least 1.2 cm/hr in first birth and 1.5 cm/hr in subsequent. No change for 2 hours → arrest of active phase.
  • Stage 2 = complete cervical dilation (10 cm) through delivery of the fetus.
    • Usually < 2 hours in 1st birth and < 1 hr in subsequent.
    • Epidural can add an hour.
    • Delivery = 4 cardinal movements:
      • Mnemonic: F-I-E-ER.
      • Flex chin to chest,
      • internally rotate the fetal occiput anteriorly,
      • extend the head as it approaches vulva,
      • then externally rotate the head to face mom’s left or right so that one shoulder can be delivered first.
    • If anterior shoulder gets stuck → shoulder dystocia, an emergency.
      • Can treat by hyperflexing the hips (McRoberts maneuver), suprapubic pressure, episiotomy, or rotating the fetal body in the vaginal canal.
  • Stage 3 = after birth through delivery of placenta.
    • Usually < 30 mins.
  • Progression of labor depends on Power (contractions, pushing), Passenger (fetal size, lie, presentation, position), and Pelvis (shape and size).

Fetal Monitoring

  • Monitor fetal well-being w/ continuous or intermittent heart rate monitoring:
    • Continuous – external doppler monitoring or internal electrode (requires membrane rupture)
    • Intermittent auscultation – in low risk, stage 1 = every 30 mins after a contraction, stage 2 = every 15 mins after contraction. In high risk, increase frequency to 15 mins/5 mins.
  • Normal heart rate data:
    • Baseline (= average) btw 110 and 160 bpm.
      • Bradycardia → maternal hypothermia, meds, congenital heart block, fetal distress, or normal variant.
      • Tachycardia → most often maternal fever, also can be meds or fetal arrhythmias.
    • Variability:
      • – affected by any autonomic nervous system factor – sleep cycle, CNS depressant meds, congental neuro problems, prematurity.
      • Fetal hypoxia → acidemia → impaired variability. Normal variability makes acidemia unlikely.
      • Short term variability (requires scalp electrode)
        • = variation in rate from one beat to the next. Normal = 6 – 25 bpm.
      • Long term variability
        • = variability over 1 min, with normal oscillations at 3-5 cycles/min.
  • Periodic heart rate changes from baseline:
    • Accelerations
      • = + 15 bpm for > 15 sec – a good sign, whether spontaneous or after contractions, exam, etc. Rules out fetal pH > 7.2.
    • Decelerations from baseline.
      • Early decelerations coincide w/ contraction
        • – result of compression of fetal head, not a problem.
      • Late deceleration starts at or after the peak of contraction
        • – indicate uteroplacental insufficiency! Can happen w/ epidurals, oxytocin → uterine hyperstimulation. Conditions that impair placental circulation will exacerbate – maternal HTN, DM, long pregnancy, abruption.
      • Variable deceleration
        • – abrupt drop and return to baseline, occurs variably w/ respect to contractions. Most common type. Probably due to umbilical cord compression during contractions. Usually not associated w/ fetal hypoxemia.

Contractions

  • Can assess frequency of contractions w/ external tocodynamometer.
    • Can assess contraction strength by palpating uterus or using an intrauterine pressure catheter.
    • IUPC is useful when 1st stage not progressing, requires membrane rupture.
  • If contractions not enough → IV oxytocin.
    • Can cause uterine hyperstimulation = 6+ contractions/10 mins w/ non-reassuring fetal heart rate abnormalities (e.g. late decelerations).
    • Reduce/discontinue oxytocin, give oxygen via face mask.

Cesarean Section

  • 20% of deliveries are C-sections.
    • Can also use forceps or vacuum assistance if cervix is fully dilated, membranes are ruptured, scalp is presented, and no problem with head/pelvis sizes.

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