Normal Labor and Delivery

What is the natural progression of pregnancy?

1. As the patient nears the end of pregnancy the uterus will prepare for delivery with painless uterine contractions (Braxton-Hicks Contractions)

   1. patient will often report that the baby is dropping or getting lower in the pelvis

2. Patient will experience signs of labor such as contractions, leaking or bleeding where they need to go to the hospital

   1. labor is defined as contractions plus cervical dilation or thinning

   2. we want to see if the amniotic sac has broken (broken water)

3. If a patient is in labor, they are admitted and put into delivery

   1. following delivery, mom is admitted to the mother baby unit where they breast feed and other things

What are the four phases of uterine activity?

Quiescence
Activation
Stimulation
Involution

What is Quiescence Phase?

Quiescence Phase is where the majority of pregnancy is spent

1. Uterus is growing and becoming more vascular to accommodate the fetus

   1. smooth muscle is inactive and cells are unresponsive while the cervix maintains the structural integrity

What is Activation Phase

Activation Phase occurs in the last 6-8 weeks of pregnancy where the uterus and cervix get ready for labor

1. Many shifts occur during this time and are associated with withdrawal of progesterone leading to increased activity

   1. Myometrium will express contraction associated proteins, which makes it more responsive to contractions

2. The lower uterine segment develops separate from the upper segment

   1. lower uterine segment is relaxed while the upper uterine segment contracts to push the baby out

3. Oxytocin receptor levels will increase

4. Cervix will ripen via hyaluronic acid, prostaglandin, and cytokines to make it thinner

What is Stimulation Phase

Stimulation phase is where childbirth occurs

1. a digital vaginal exam is conducted to see if the cervix is dilated (progresses to 10 cm)

   1. Cervix will thin out or efface as labor progresses

2. Both these processes need to occur for labor to progress

What is Stage 1 of Labor?

Stage 1 of Labor is cervical dilation and effacement due to forceful uterine contractions

1. It is mediated by prostaglandins and oxytocin and is subdivided into a latent and active phase

   1. latent phase is 0-6cm of dilation and can vary from hours to days

   2. active phase is when the cervix dilates past 6 cm and is where there is more rapid cervical change

What is the second stage of labor

Complete dilation of the cervix as well as fetal expulsion

What is stage 3 of labor

Stage 3 starts after delivery of the fetus and ends with delivery of the placenta

1. Placenta separates from the wall of the uterus with signs of placental separation being cord lengthening and bleeding

What is Involution

Involution is the period after delivery of the fetus

1. Myometrium contracts to compress the large uterine vessels to allow for thrombosis

2. Lactogenesis and milk production occur

   1. Ovulatory signals begin

3. Uterus and cervix return to normal

What is Fetal Presentation

Fetal Presentation is the part of the fetus that is pointing downward into the cervix

1. Most of the time it is head side down (cephalic) and the majority of the time the fetus does it on its own

What is a normal fetal heart rate?

110-160 is the normal fetal heart rate

1. there is variability in the amplitude of fetal heart rate, with it being the number one indicator of fetal well being. It is categorized in four ways

   1. Absent or no change

   2. Minimal, little change and less than five beats per minute

   3. Normal, moderate 6-25 bpm

   4. Marked, greater than 25 bpm

2. Accelerations are increases in fetal heart rate above the baseline and are indicative of fetal well-being

   1. categorized by 15 beats per minute increase from baseline over 15 seconds

What are Decelerations?

Fetal Heart Rate Tracing involves decelerations that are in three types:

1. Early Decelerations (Normal) - mirror contraction onset

   1. associated with uterine contractions and are caused by compression of the fetal head leading to vagal activity

2. Variable Decelerations

   1. deceleration in heart rate can occur at any time and represent umbilical cord compression due to chemoreceptors and baroreceptors

   2. worrisome if recurrent

3. Late Decelerations - begin after a contraction starts and recover after contraction ends

   1. associated with uteroplacental insufficiency due to decreased uterine perfusion or decreased placental function

What are the seven cardinal movements of labor?

Engagement - head travels into the pelvic inlet

Flexion - smallest diameter of the head passes through

Descend - where the fetus starts coming through the canal

Internal Rotation - anterior rotation of the back of the head towards the pubic symphysis

Extension - head is delivered

External Rotation - head rotates back to the shoulders

Expulsion - rest of body is delivered