Contents · 13 sections
- 1. Causes of the onset of labor
- 2. Prodromal phase and preliminary period
- 3. Diagnosis of the onset of labor
- 4. Stages of labor
- 5. Biomechanism of labor (occiput anterior presentation)
- 6. Partograph
- 7. Fetal monitoring
- 8. Analgesia
- 9. Active management of the third stage
- 10. Neonatal assessment
- 11. Abnormalities and complications
- 12. Indications for cesarean section
- 13. FAQ
In a nutshell. Labor is the physiological process of expulsion of the fetus and placenta. Three stages: I — cervical dilation (latent phase up to 6 cm, active phase 6–10 cm; nulliparous up to 12–20 h, multiparous up to 7–14 h); II — expulsion of the fetus (up to 3 h in nulliparous, up to 2 h in multiparous); III — placental stage (up to 30 min, active management reduces bleeding). Biomechanism in occiput anterior presentation: flexion → internal rotation → extension → external rotation. Management — partograph (alert line at ≥ 4 h arrest in the active phase), CTG, analgesia, active management of the third stage (10 IU oxytocin i.m.).
1. Causes of the onset of labor
- Decrease in progesterone, increase in estrogens and myometrial oxytocin receptors.
- Increase in prostaglandins in the myometrium and cervix.
- Activation of the fetal HPA axis (cortisol → surfactant + placental stimulation).
- Uterine distension, Ferguson reflex (pressure on the cervix → oxytocin).
2. Prodromal phase and preliminary period
- Lowering of the uterine fundus 2–3 weeks prior in nulliparous women.
- Weight loss of 0.5–1 kg.
- Loss of the mucous plug.
- Irregular Braxton Hicks contractions.
- Pathological preliminary period — > 6 h of painful irregular contractions without dilation → obstetric management.
3. Diagnosis of the onset of labor
- Regular contractions ≥ 1 in 10 min with progressive intensification.
- Cervical effacement and dilation.
- Rupture of membranes (amniotic sac rupture) — with prelabor rupture of membranes < 37 weeks — PPROM, > 37 weeks — premature rupture of membranes.
4. Stages of labor
Stage I — cervical dilation
- Latent phase: from the onset of regular contractions up to 6 cm (previously up to 4 cm).
- Active phase: 6–10 cm, rate ≥ 1 cm/h in nulliparous, ≥ 1.5 cm/h in multiparous.
- Duration: nulliparous up to 12–20 h, multiparous 7–14 h.
- Mechanisms: contraction, retraction, distraction.
Stage II — expulsion
- From full dilation to the birth of the fetus.
- Duration: nulliparous up to 3 h, multiparous up to 2 h; with epidural anesthesia — plus 1 h.
- Two phases: passive (until the urge to push) and active (pushing).
- Management: maternal positioning, CTG monitoring, episiotomy when indicated (not routine).
Stage III — placental stage
- From the birth of the fetus to the delivery of the placenta.
- Duration up to 30 min with active management.
- Signs of placental separation: Schroeder, Ahlfeld, Kustner-Chukalov, Dovzhenko.
5. Biomechanism of labor (occiput anterior presentation)
- Engagement of the fetal head (flexion, oriented toward the pelvic inlet).
- Flexion of the head (axis passes through the posterior fontanelle).
- Internal rotation of the head (from oblique to direct diameter).
- Extension of the head (birth of the parietal, frontal, and facial parts).
- External rotation of the head + internal rotation of the shoulders.
- Birth of the shoulders (anterior first, then posterior) and the trunk.
Leading point — posterior fontanelle; guiding axis — plane of the inlet → outlet of the pelvis.
6. Partograph
- Graphical representation of labor dynamics: cervical dilation, fetal head position, fetal heart rate, contractions, maternal BP/Tº.
- «Alert line» — 1 cm/h starting from 4 cm (or 6 cm in current guidelines).
- "Action line" — 4 hours to the right of the "alert line" → intervention (amniotomy, oxytocin, Cesarean section).
- WHO 2020: partogram ≥ 6 cm, with less dogmatism, individualized approach.
7. Fetal monitoring
- Intermittent auscultation in low-risk cases: every 15 min in the 1st stage, every 5 min in the 2nd.
- Continuous CTG: high risk, oxytocin induction, epidural anesthesia, preeclampsia, IUGR.
- CTG categories (FIGO): normal, suspicious, pathological.
- Assessment of baseline FHR (110–160), variability (5–25), accelerations, decelerations.
- In case of pathological CTG — fetal scalp pH/lactate, management (speeding up delivery, emergency C-section).
8. Analgesia
- Non-pharmacological methods: breathing techniques, movement, water immersion, TENS, massage.
- Nitrous oxide 50/50 — safe, rapid elimination.
- Regional anesthesia: epidural (L3–L4, bupivacaine/ropivacaine + fentanyl) — the gold standard.
- Spinal, combined spinal-epidural — for Cesarean section.
- Pudendal block — for operative vaginal delivery, episiotomy.
- Parenteral opioids (pethidine, remifentanil) — less preferred due to the risk of neonatal respiratory depression.
9. Active management of the third stage
- Oxytocin 10 IU IM after the delivery of the anterior shoulder.
- Controlled cord traction after placental separation.
- Uterine massage after the delivery of the placenta.
- Reduces PPH by 60%.
10. Neonatal assessment
- Apgar score at 1 and 5 min: heart rate, respiration, tone, reflexes, color — 0–2 points each.
- 7–10 — satisfactory; 4–6 — moderate asphyxia; 0–3 — severe.
- In case of low score — resuscitation per protocol (drying, stimulation, bag-valve-mask ventilation, intubation, epinephrine).
- Skin-to-skin contact, delayed cord clamping ≥ 1 min (improves iron stores).
- Early initiation of breastfeeding within 1 hour.
11. Abnormalities and complications
Labor abnormalities
- Uterine inertia: primary and secondary; treatment — oxytocin 1 mIU/min with titration.
- Dysfunctional labor — hypertonic/spastic; epidural anesthesia, antispasmodics.
- Tachysystole / hyperstimulation — tocolysis (hexoprenaline).
Early complications
- Shoulder dystocia: McRoberts maneuver (leg flexion), suprapubic pressure, Woods screw maneuver, delivery of the posterior arm.
- Postpartum hemorrhage: 4Ts — tone (atonicity), trauma (lacerations), tissue (retained placental tissue), thrombin (coagulopathy).
- Perineal tears of degree I–IV; episiotomy according to indications.
- Umbilical cord prolapse — emergency C-section.
- Placental abruption, amniotic fluid embolism.
12. Indications for cesarean section
- Elective: placenta previa, multiple pregnancy (depending on type), breech presentation in primigravidae, previous C-section with a classical vertical incision, HIV with viral load > 1000, active genital herpes, macrosomia > 4500 g in diabetes.
- Emergency: acute fetal hypoxia, placental abruption, cord prolapse, labor dystocia with no progress, uterine rupture risk.
13. FAQ
What is "delayed cord clamping"?
Clamping 1–3 minutes after birth — increases newborn iron stores by 30%, reduces anemia at 6 months. WHO standard for all term infants, especially in Cesarean section.
What does "active management of the third stage of labor" mean?
Oxytocin + controlled cord traction + uterine massage. Reduces PPH by 60%. An alternative is physiological expectant management (up to 60 min), only in low-risk women.
Is routine episiotomy necessary?
No; episiotomy is performed only when indicated (risk of grade III–IV tears, fetal distress, operative vaginal delivery). Routine practice increases the rate of grade III–IV tears.
When is induction of labor indicated?
Post-term pregnancy ≥ 41 weeks, PROM, preeclampsia, poorly controlled gestational diabetes, IUGR, intrahepatic cholestasis of pregnancy. Cervical status is assessed by Bishop score — < 6 requires pre-induction (prostaglandins, mechanical methods).
What to do in case of shoulder dystocia?
McRoberts position + suprapubic pressure (HELPERR algorithm). Do not pull on the fetal head! If unsuccessful — Woods maneuver, delivery of the posterior arm, if necessary — clavicle fracture (cleidotomy) or Zavanelli maneuver (head replacement and C-section).
See also: Preeclampsia · PPH · Apgar score · Cesarean section · Obstetrics Catalog