Parturition

Question 1

Define pre-term, term and post-term gestation periods

Answer 1

• pre-term: 24-37 weeks gestation
• term: 37-42 weeks
• post-term: after 42 weeks

Question 2

What are the things you can use to confirm the gestational age?

Answer 2

• using pregnancy wheels, adding 280 days to LMP (last menstrual period) to find EDD
• EDD (estimated date of delivery): dates or scan (LMP + 9 months + 7 days)
• ultrasound scan
• SFH: height measured from pubic symphysis to top of uterus

Question 3

Describe the most common cephalic presentation of babies

Answer 3

• the back of the baby’s head faces the mother’s front (occiput anterior)
• the occiput is the determining point of the cephalic presentation

Question 4

Describe diagnosing labour

Answer 4

History:

• labour pains
• show (mucus plug)
• sudden loss of fluid from the vagina

Abdo exam:

• uterine contractions
• frequency (3 every 10 mins)
• duration (40-60s)
• severity (>80mmHg)

Pelvic examination:

• cervical dilatation (opening)
• effacement (thinning of cervix)
• consistency
• position
• level of presenting part

Question 5

Describe the stages of labour and the physiology behind it

Answer 5

• 0: quiescent - maintained by progesterone and relaxin
• 1: initiation of parturition, extending to complete cervical dilatation - increase in gap junction connectivity (prostaglandins), increase in oxytocin receptor numbers (oestrogen)
• 2: active labour, from complete cervical dilatation to delivery - oxytocin release triggered by the Ferguson reflex, prostaglandins
• 3: from delivery to expulsion of the placenta and final uterine contractions - oxytocin

Question 6

What are the inhibitory factors of pregnancy that keep the stage of labour at 0?

Answer 6

• progesterone
• prostacyclin
• relaxin
• NO
• PTH related peptide
• corticotropin- releasing hormone
• human placental lactogen

Question 7

What are the uterotropin factors that help activate labour?

Answer 7

• oestrogen
• progesterone
• prostaglandins
• corticotropin-releasing hormone

Question 8

What are the uterotonin factors that maintain the stimulation of labour (phase 2)?

Answer 8

• prostaglandins

- oxytocin

Question 9

What are the factors that maintain involution of labour (phase 3)?

Answer 9

• oxytocin

- thrombin

Question 10

Describe the positive feedback loop of oxytocin during labour

Answer 10

• nerve impulses from cervix transmitted to brain
• brain stimulates pituitary gland to secrete oxytocin
• oxytocin carried in bloodstream to uterus
• oxytocin stimulates uterine contractions and pushes baby towards cervix
• head of baby pushes against cervix
  (loops back)

Question 11

Describe the events occuring at the 3 stages of labour

Answer 11

• stage 1: the cervix relaxes, causing it to dilate and thin out
• stage 2: uterine contractions increase in strength and the infant is delivered
• stage 3: the placenta is expelled

Question 12

What defines the latent phase of labour and the active phase?

Answer 12

• latent: <4cm dilation

- active: 4-10cm dilation (and rupture of membranes)

Question 13

Describe flexion during the second stage of labour/delivery

Answer 13

uterine contractions push the foetus downwards, while the cervix resists resulting in increased flexion of the head

Question 14

Describe the pelvic stations

Answer 14

• measured in stations and describes the level at which the baby’s head is at
• (-3) is when the head is above the pelvis
• 0 is when the head is at the bottom of the pelvis
• +3 is when the head is crowning

Question 15

What is an episiotomy and when is the procedure done?

Answer 15

• an incision made in the perineum to enlarge the opening for the baby to pass through
• done when the baby needs to be quickly delivered

Question 16

What are the signs of placental separation?

Answer 16

• lengthening of cord
• gush of blood
• uterus (is hard, mobile from side to side, heigh rises to umnbilicus)