Onset of labour

Question 1

When does labour and delivery usually occur?

Answer 1

37-42 weeks

Question 2

How many stages are there of labour?

Answer 2

3

Question 3

When does the first stage start and end?

Answer 3

• from onset of labour (true contractions) to 10cm cervical dilation and effacement(opening up)
• “show” refers to mucus plug falling out from the cervix

Question 4

When does the second stage start and end?

Answer 4

-from 10cm cervical dilation until delivery of the baby

Question 5

When does the third stage start and end?

Answer 5

-from delivery of the baby until delivery of the placenta

Question 6

What are the three phases of the first stage?

Answer 6

• latent phase -> from 0 to 3cm cervical dilation which progresses at 0.5cm/hour with irregular contractions
• active phase -> from 3cm to 7cm cervical dilation which progresses at 1cm/hour with regular contractions
• transition phase -> from 7cm to 10cm cervical dilation which progresses at 1cm/hour with strong, regular contractions

Question 7

What are Braxton-hicks contractions?

Answer 7

• occasional irregular contractions usually felt during the second and third trimester
• not true contractions and do not indicate onset of labour
• staying hydrated and relaxed helps reduce these

Question 8

What are the signs for diagnosing the onset of labour?

Answer 8

• show
• rupture of membranes
• regular, painful contractions
• dilating cervix on examination

Question 9

What does rupture of membranes mean?

Answer 9

the amniotic sac has ruptured

Question 10

What does prelabour rupture of membranes mean?

Answer 10

amniotic sac has ruptured before onset of labour

Question 11

What does preterm prelabour rupture of membranes mean?

Answer 11

amniotic sac has ruptured before onset of labur and before 37 weeks

Question 12

What does a prolonged rupture of membranes mean?

Answer 12

amniotic sac ruptures more than 18 hours before delivery

Question 13

What is prematurity defined as?

Answer 13

birth before 37 weeks gestation

Question 14

What gestation are babies considered non-viable?

Answer 14

• below 23 weeks
• with babies born at 23 weeks having 10% survival so resuscitation not offered to those without signs of life

32-37 weeks=moderate to late preterm
28-32 = very preterm
<28= extreme preterm

Question 15

What are the options for prophylaxis of preterm labour?

Answer 15

• vaginal progesterone

- cervical cerclage

Question 16

How does vaginal progesterone act as prophylaxis for preterm labour?

Answer 16

• progesterone maintains pregnancy and prevents labour by decreasing activity of myometrium and preventing cervix remodelling for delivery
• offered to women with cervical length < 25mm on US between 16-24 weeks

Question 17

How does cervical cerclage act as prophylaxis for preterm labour?

Answer 17

• involves putting a stitch in cervix to keep it closed and stitch is removed when woman goes into labour or reaches term
• offered to women with cervical length < 25mm on US between 16-24 weeks, who also have had previous prem birth or cervical trauma
• ‘rescue’ cervical cerclage may also be offered between 16-27+6 weeks when there is cervical dilation without ROM

Question 18

How can rupture of membranes be diagnosed?

Answer 18

• by speculum exam revealing pooling of amniotic fluid in the vagina. no tests required if found
• when there is doubt test for IGFB-1 (protein high in amniotic fluid) in vaginal fluid or test for PAMG-1

Question 19

How is PPROM managed?

Answer 19

• prophylactic antibiotics should be given to prevent development of chorioamnionitis
• erythromycin 250mg 4ds for 10 days or until labour
• induction of labour may also be offered from 34 weeks

Question 20

What does preterm labour with intact membranes involve?

Answer 20

-regular painful contraction and cervical dilation without rupture of amniotic sac

Question 21

How is preterm labour with intact membranes diagnosed?

Answer 21

• speculum exam to assess for cervical dilatation
• if more than 30 weeks gestation then a tVUS is needed to assess cervical length –> if <15mm management of preterm labour can be offered
• fetal fibronectin can be used instead of US and result of < 50ng/ml is considered negative so preterm labour unlikely

Question 22

How is preterm labour with intact membranes managed?

Answer 22

• fetal monitoring (CTG or intermittent ausculation)
• tocolysis with nifedipine (suppresses labour)
• maternal corticosteroids can be offered before 35 weeks to reduce neonatal morbidity and mortality
• IV magnesium sulphate can be given before 34 weeks to help protect babys brain
• delayed cord clamping or cord milking can increase blood volume and hb in baby at birth

Question 23

What does tocolysis involve?

Answer 23

• involves using medications to stop uterine contractions
• nifedipine is first choice
• atosiban is an alternative
• tocolysis can be used between 24 and 33+6 weeks in preterm labour to delay delivery and buy time
• it is only used for short term (less than 48 hours)

Question 24

How does maternal corticosteroids help in preterm labour?

Answer 24

• helps develop fetal lungs and reduce RDS after delivery
• used in women with suspected preterm labour and babies < 36 weeks
• eg 2 doses of IM betamethasone 24 hours apart