Parturition Flashcards
Define parturition.
the process of giving birth to a child
What is the standard length of pregnancy ? What is EDD ?
40 weeks from date of LMP.
EDD = estimated delivery date
Define term, pre-term and post-term gestation period.
Term: Having given birth between 37 and 42 weeks
Pre-term: Having given birth before 37 completed weeks (bad)
Post-term: Having given birth after 42 weeks (bad)
Identify ways to confirm gestational age, and state which of these is the best.
1) USS (best way, using crown-rump length to date gestational period)
2) LMP, and calculating 40 weeks from then (but memory unreliable, and follicular phase variable and ovulation doesn’t always occur on day 14)
3) Clinical Examination (palpate uterus)
How does the body prevent parturition occurring until around week 40 ?
3 main ways:
- Cervix is mechanical barrier blocking baby coming out
- Uterus quiescence (due to down regulation of gap junctions, down regulation of oxytocin, and presence of progesterone, uterus stays relaxed)
- Amniotic sac containing amniotic fluid, around baby. In this fluid, prostaglandins which stimulate labor. BUT because this is intact and fluid not released, keeping pregnancy in abdomen.
Define cervical ripening, and explain its importance.
Softening of the cervix, mediated by prostaglandins, that typically begins prior to the onset of labor contractions. This is necessary for cervical dilation and effacement, and thus for the passage of the fetus.
Explain the events occurring in the 3 stages of labour. Which stage is the longest ?
Stage 1: Time of onset from regular contractions until cervix is fully dilated (longest stage)
Stage 2: From full cervical dilatation until infant is delivered (requires active pushing)
Stage 3: Delivery of placenta
Identify the main hormones associated with parturition.
prostaglandins, oestrogens, relaxin and oxytocin
Describe the state of the uterus in each of the stages of parturition, and identify the main hormones involved in each of these.
♦ Stage 0: Uterus quiescent (Maintained by progesterone (which subsequently drops) and relaxin)
♦ Stage 1: Uterine ‘awakening’, initiation of parturition, extending to complete cervical dilatation (Increase in gap junction connectivity (caused by prostaglandins), increase in oxytocin receptor numbers (due to rise in oestrogen))
♦ Stage 2: Active labour, from complete cervical dilatation to delivery (Oxytocin (causes uterus to contract) release triggered by the Ferguson reflex (when perineum is stretched and baby coming down, releases more oxytocin), prostaglandins)
♦ Stage 3: From delivery to the expulsion of the placenta and final uterine contractions (Oxytocin)
What are the main parts of the first stage of parturition. ?
1) Latent phase
- <4cm (cervix)
2) Active phase
-4cm-10cm (fully)
-Rupture of membranes (waters will break, prostaglandins
released)
What are the main parts of the second stage of parturition ?
1) Engagement (gets baby from abdomen into pelvic inlet)
2) Descent
3) Flexion
4) Internal Rotation (to be in AP diameter)
5) Extension
6) External Rotation (for infant to face sideways)
7) Expulsion (anterior shoulder, then posterior shoulder delivered)
Is the third stage of parturition an active or passive stage ? Why ?
Tend to use active management:
1) Give oxytocin as baby is being delivered (helps uterus contact and expel placenta)
2) Use controlled cord traction to pull it out
Because risk of Post-Partum Hemorrhage, can be reduced through this
What is a normal infant presentation in birth ? Identify other presentations. What are the main issues with these ?
Cephalic presentation is the usual way that infant comes out. Other presentations include:
- Breech (i.e. bottom first) (including frank breech, complete breech, footling breech) presentation
- Face
- Brow presentation
- Shoulder presentation
Issues: Unusual presentations associated with complications
Describe different ways of monitoring mother close to/during parturition.
Intrapartum monitoring (mother):
- Maternal obs (temperature, BP)
- Partograph (way of recording observations and progress e.g. cervical dilatation, strength of contractions and number of contractions)
- If membrane has ruptured then color of amniotic fluid (brown would suggest Meconium present)
Describe different ways of monitoring infant close to/during parturition.
Intrapartum monitoring (fetal):
- Fetal Heart Beat (using Pinard horn, or using Doppler Ultrasound)
- CTG monitoring (looking at heart + looking at activity of uterus)
