Labour and Delivery

Stage I

Stage I lasts from the onset of labour to full cervical dilatation (10 cm).

During the latent phase (0-4 cm) it appears little is happening, but contractions become more coordinated, stronger, and efficient. The cervix softens, effaces, begins to dilate and angle anteriorly. It lasts avg 8.6 hours in nulliparous patients and 5.3 hours in multiparous women.

Contractions are relatively painless and initially occur every 3-4 minutes. Contractions become stronger and more frequent as the cervix slowly dilates. Spontaneous rulture of membranes may occur towards the end of the latent phase.

 

During the active phase, which begins when cervix is 3-4 cm dilated, labour progresses much more rapidly. The normal rate of dilatation is 0.5-1 cm/hr in nulliparious and 1.2 cm/hr in multiparous women. It lasts on average 5.8 hours in nulliparous and 2.5 hours in multiparous women.

Contractions can become more painful as the active phase continues, and women may feel a desire to push alhtouhg this is not wise until the cervix is fully dilated.

Progress in the first stage is measured in terms of cervical effacement, dilatation, consistency of the cervix, position of the cervix, and descent of the fetal head.

 

During the first phase, mothers should be made comfortable and not push until the cervix is fully dilated.

Mothers may be more comfortable in a variety of poses, including sitting, standing, or showering.

As food will not pass through the gut during labour food should be avoided, especially if general anesthetics are possibly to be used. However, low-fibre, low-fat meals or drinks likely pose little hazard, and may in fact prevent ketoacidosis. (O'Sullivan et al, 2009).

 

The following should be monitored during the first stage:

• pulse, temperature, and blood pressure every 2 hours
• assess frequency, strength, and intensity of uterine contractions
• monitor fetal heart rate every 15 minutes
• assess cervical dilatation every 4 hours to determine progress and descent of presenting part
• discuss ongoing analgesic needs
• determine position of head

 

Progress is dependent on the 3 P's:

• Power: can do amniotomy if membranes are intact or augment with oxytocin
• Passage: shape cannot be altered - gynecoid, android, anthropoid, platypoid. Android and platypoid makes passage more difficult.
• Passenger: both head diameter and position are important; flexed head is best. Position is measured by relationship of occiput to the pelvis. Head can flex and mold to the shape of the bony pelvis

Stage II

The second stage of labour lasts from the period of full dilation to delivery.

• duration: nulliparous 30 minutes-4 hours (avg 50 minutes); mulitparous 5 minutes-2 hours (avg 20 minutes)

passive phase: from full dilatation until head descends to pelvic floor via

• descent of the fetal head usually only begins near full dilatation and in the 2nd stage, and is measured by station, represented by the ischial spines.
• protracted progress if less than 1 cm/hr in nulliparous women and less than 2 cm/hr in multiparous
• arrested if no descent over one hour in nulliparous and 30 min in multiparous

active: when bearing down efforts begin accompanying each contraction.

• strong desire to bear down; rectal pressure
• feelings of increased nausea and vomiting as the cervix reaches full dilatation

 

Progress

Progress in the second stage can be negatively affected by epidural analgesia through inhibition of oxytocin; augmentation may be required.

Progress is again dependent on the three P's:

• power of contractions
• passage
• passenger: flexion or position can be enhanced using manual, vacuum, or forceps technique

 

 

Six Cardinal Mechanisms of Labour

Descent

• occurs prior to onset and then throughout labour, with other mechanisms superimposed on it
• occurs at greater rate during latter part of 1st stage and 2nd stage

Flexion

• present before labour to some degree due to natural muscle tone
• further encouraged during labour by resistance from cervix, walls of pelvis, and pelvic floor
• optimizes presenting diameter of head

Internal Rotation

• head enters transversely and then rotates so that occiput is turned towards symphysis pubis (OA, occiput anterior position)
• 20% of the time, the head rotates OP, occiput posterior, though at least 75% of fetuses will rotate back as labour progresses

Extension

• to follow the path of the vagina, as the head moves under the symphysis it needs to move from flexion to extension
• make sure there's not too much extension
• crowning - when the largest diameter of the head is encircled by the vaginal opening, occurs during extension

External Rotation/Restitution

• the delivered head now rotates back to the transverse position, as it originally was, realigning the head with the back and shoulders

Delivery/Expulsion

• as descent continues, anterior shoulder delivers under the symphysis pubis, followed by the posterior shoulder. The rest of the body quickly follows

Stage III

• delivery of baby and placenta; duration avg 5-10 min; range 0-30 min
• signs of placental separation:
  • gush of blood from vagina
  • ubbilical cord lengthening
  • fundus of uterus moves up into abdomen
  • uterus becomes firm and globular
• watch closely for postpartum hemorrhage
• inspect cervix, vagina, and perineum for lacerations and repair if necessary
• inspect placenta to ensure complete removal

Stage IV

• especially during the 1st hour, the risk of postpartum hemorrhage is highest

Lochia is post-partum discharge, which can last up to 6 weeks