Onset of labour Flashcards
When does labour and delivery usually occur?
37-42 weeks
How many stages are there of labour?
3
When does the first stage start and end?
- from onset of labour (true contractions) to 10cm cervical dilation and effacement(opening up)
- “show” refers to mucus plug falling out from the cervix
When does the second stage start and end?
-from 10cm cervical dilation until delivery of the baby
When does the third stage start and end?
-from delivery of the baby until delivery of the placenta
What are the three phases of the first stage?
- 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
What are Braxton-hicks contractions?
- 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
What are the signs for diagnosing the onset of labour?
- show
- rupture of membranes
- regular, painful contractions
- dilating cervix on examination
What does rupture of membranes mean?
the amniotic sac has ruptured
What does prelabour rupture of membranes mean?
amniotic sac has ruptured before onset of labour
What does preterm prelabour rupture of membranes mean?
amniotic sac has ruptured before onset of labur and before 37 weeks
What does a prolonged rupture of membranes mean?
amniotic sac ruptures more than 18 hours before delivery
What is prematurity defined as?
birth before 37 weeks gestation
What gestation are babies considered non-viable?
- 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
What are the options for prophylaxis of preterm labour?
- vaginal progesterone
- cervical cerclage
How does vaginal progesterone act as prophylaxis for preterm labour?
- 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
How does cervical cerclage act as prophylaxis for preterm labour?
- 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
How can rupture of membranes be diagnosed?
- 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
How is PPROM managed?
- 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
What does preterm labour with intact membranes involve?
-regular painful contraction and cervical dilation without rupture of amniotic sac
How is preterm labour with intact membranes diagnosed?
- 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
How is preterm labour with intact membranes managed?
- 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
What does tocolysis involve?
- 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)
How does maternal corticosteroids help in preterm labour?
- 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
