Chapter 13: Labor and Birth Process

Initiation of Labor and Chemical Signals

• What Is Labor?: Labor is the natural process a pregnant body goes through to get ready and push the baby out into the world. It includes physical changes in the body and emotional changes for the family.

• How the Body Prepares: Over days or weeks, the uterus (womb) and cervix (the lower opening of the womb) change shape and get softer.

• Why Does Labor Start?: Doctors do not know the exact single trigger, but it happens because of several natural body signals working together:

  • Stretching of the Uterus: As the baby and the fluid around the baby grow bigger, they stretch the uterine muscles, which encourages them to start squeezing (contracting).

  • Hormone Balance Shift: During pregnancy, a hormone called progesterone keeps the womb relaxed and quiet. Near the end of pregnancy, estrogen levels go up while progesterone goes down, taking away the calming effect and letting the womb get ready to work.

  • Cell Bridges (Gap Junctions): Rising estrogen causes muscle cells in the womb to form tiny connection points called gap junctions. These let electrical signals jump quickly between cells so the whole womb can squeeze together in a coordinated way.

  • Oxytocin and Prostaglandins: Oxytocin is a hormone that causes the womb to squeeze. As birth gets close, the womb gets much more sensitive to oxytocin. Oxytocin also tells the body to make prostaglandins, which are chemicals that soften the cervix and help it open up (dilate).

  • Two Jobs of Contractions: Contractions have two main goals: to open the cervix and to push the baby through the birth canal.

  • Letting Labor Start Naturally: Waiting for labor to start on its own (instead of using medicine to start it) helps natural hormones do their jobs best, which also supports bonding after birth.

Early Warning Signs That Labor Is Near

• Practice Contractions (Braxton Hicks):

  • What they feel like: Irregular tightening or pulling in the front of the belly and groin.

  • Purpose: They help soften the cervix and move it forward, but they are not the real thing.

  • Timing and Relief: They usually last around $30\text{ seconds}$ (up to $2\text{ minutes}$). They do not get stronger over time, and they usually slow down or stop if the person walks around, drinks a glass of water, or rests.

  • When to Call the Doctor: If these happen more than $4\text{ to }6\text{ times per hour}$ and last longer than $30\text{ seconds}$, especially before $38\text{ weeks}$, a doctor needs to check for preterm labor.

• Late Preterm Babies: Babies born between $34\ 0/7\text{ weeks}$ and $36\ 6/7\text{ weeks}$ are called "late preterm" and still need extra medical support like earlier premature babies.

• The Baby Drops (Lightening):

  • What happens: The baby settles down into the mother's pelvis bones.

  • Feelings: It becomes easier for the mother to breathe and heartburn decreases because pressure is taken off the lungs and stomach. However, it creates more pressure on the bladder (needing to pee more often) and can cause leg cramps.

  • When it occurs: In a first pregnancy, this often happens $2\text{ weeks}$ or more before labor. In people who have had babies before, it might not happen until labor actually starts.

• Bloody Show: During pregnancy, a plug of mucus seals the cervix to keep germs out. As the cervix softens and stretches, this plug comes loose. Tiny blood vessels may break, creating a pink or slightly bloody mucus discharge called the bloody show.

• Cervix Softening (Ripening): Before labor, the cervix changes from firm (like the tip of your nose) to soft and stretchy (like your earlobe or butter) so it can open. This change can happen anywhere from $1\text{ month}$ to $1\text{ hour}$ before labor.

• Water Breaking (Prelabor Rupture of Membranes):

  • What it is: The fluid-filled amniotic sac protecting the baby tears before labor begins. It can feel like a big gush of warm water or a slow, constant trickle.

  • Important safety rules: Once the bag breaks, germs could travel up into the womb, and there is a risk the umbilical cord could slip down first. The mother should contact her healthcare provider immediately.

Telling the Difference Between True Labor and False Labor

• Contraction Timing:

  • True Labor: Regular timing; contractions get closer and closer together (usually every $4\text{ to }6\text{ minutes}$, lasting $30\text{ to }60\text{ seconds}$).

  • False Labor: Irregular; no steady pattern.

• Contraction Strength:

  • True Labor: Gets steadily stronger over time, causing deep pelvic pressure.

  • False Labor: Stays weak or random (a strong one might be followed by an easy one).

• Where Pain Is Felt:

  • True Labor: Starts in the lower back and wraps around toward the front of the belly.

  • False Labor: Felt mostly in the front of the belly or groin.

• Effect of Movement:

  • True Labor: Contractions keep going strong even if the person walks, rests, or changes positions.

  • False Labor: Contractions often stop or slow down when walking, resting, or drinking water.

• When to Go to the Hospital:

  • True Labor: Head to the hospital when contractions happen consistently every $5\text{ minutes}$, last $45\text{ to }60\text{ seconds}$, and are strong enough that the person cannot talk through them.

  • False Labor: Drink water and take a walk; if the tightening stops, it is safe to stay home.

Stages and Phases of Labor

• The Four Stages of Labor:

  • First Stage (Opening the Cervix): From $0\text{ cm}$ to full dilation at $10\text{ cm}$. It is divided into two phases: Latent and Active.

  • Second Stage (Pushing the Baby Out): From complete opening ($10\text{ cm}$) until the baby is born. Can last up to $3\text{ hours}$.

  • Third Stage (Delivering the Placenta): From the birth of the baby until the placenta comes out. Usually takes $5\text{ to }10\text{ minutes}$, but up to $30\text{ minutes}$ is normal.

  • Fourth Stage (Recovery): The first $1\text{ to }4\text{ hours}$ after birth, when the mother's body begins to rest and stabilize.

• Stage 1 Details (Dilation):

  • Can last up to $20\text{ hours}$ for a first baby and up to $14\text{ hours}$ for someone who has had a baby before.

  • Latent Phase ($0\text{ to }6\text{ cm}$): The cervix opens slowly from $0\text{ to }6\text{ cm}$ and thins out from $0\%\text{ to }40\%$. Contractions occur every $5\text{ to }10\text{ minutes}$ and feel like mild cramps. The mother is usually talkative and excited.

  • Active Phase ($6\text{ to }10\text{ cm}$): The cervix opens much faster ($1.2\text{ to }1.5\text{ cm/hour}$) until it reaches $10\text{ cm}$, thinning out completely ($100\%$). Contractions come every $2\text{ to }5\text{ minutes}$ and are much stronger. The mother becomes very quiet and focused on breathing.

• Stage 2 Details (Pushing and Birth):

  • Contractions come every $2\text{ to }3\text{ minutes}$ and last $60\text{ to }90\text{ seconds}$.

  • The Push Reflex (Ferguson Reflex): When the baby's head presses against the pelvic floor, it triggers a strong, automatic urge to push.

  • Crowning: When the widest part of the baby's head can be seen at the opening and does not slip back inside between pushes.

  • Best Pushing Method: Open-glottis pushing (pushing while breathing out or making sounds) is recommended over holding your breath because it keeps oxygen flowing well to the baby.

• Stage 3 Details (Placenta Delivery):

  • After the baby is born, the womb shrinks, peeling the placenta away from the uterine wall. Normal blood loss is less than $500\text{ mL}$. Skin-to-skin cuddling with the baby starts right away.

• Stage 4 Details (Recovery):

  • The womb must stay firmly squeezed down like a hard ball to stop bleeding from the blood vessels where the placenta was attached.

How the Mother and Baby Adapt During Labor

• Mother's Body Changes:

  • Heart and Blood: Heart rate rises slightly, blood output increases by $30\%\text{ to }40\%$, and blood pressure goes up during contractions.

  • Immune System: White blood cell count goes up to $20,000\text{ cells/mm}^3$ to handle stress and healing.

  • Lungs: Breathing speeds up.

  • Stomach: Digestion slows down greatly.

  • Emotions: High fear and stress release stress chemicals (adrenaline) that can slow down labor. Feeling supported and safe helps labor move along smoothly.

• Baby's Body Changes:

  • Heart Rate: Temporarily speeds up or slows down slightly as the head is squeezed during contractions.

  • Oxygen: Normal contractions briefly lower blood flow, but healthy babies have extra oxygen stores to handle it.

  • Lungs: Going down the birth canal squeezes extra fluid out of the baby's chest, preparing the baby to take its first breath of air.

The Critical Factors of Labor (The Ps)

• The 5 Core Ps:

  • Passageway: The mother's pelvic bones and birth canal.

  • Passenger: The baby and the placenta.

  • Powers: The squeezes of the womb (contractions) and the mother's pushing.

  • Position: How the mother sits, stands, or moves.

  • Psychological Response: How calm, confident, and supported the mother feels.

• The Extra 5 Ps: Philosophy (natural approaches), Partners (support people), Patience (giving labor time), Preparation (classes and learning), and Pain relief (comfort tools and medicines).

Passageway (The Pelvis and Birth Canal)

• Pelvic Bones:

  • The baby's head must fit through the mother's rigid pelvis bones. Only the tailbone (coccyx) can bend backward to give extra room.

  • Pregnancy hormones (like relaxin) soften the pelvic joints so they can stretch slightly.

• Pelvis Shapes:

  • Gynecoid: Round and roomy; the easiest shape for giving birth.

  • Anthropoid: Oval-shaped; usually good for birth.

  • Android: Heart-shaped like a typical male pelvis; narrow, often making vaginal delivery difficult.

  • Platypelloid: Flat shape; rare and difficult for vaginal birth.

  • Note: Most people have a blend of shapes rather than just one pure type.

• Soft Tissues:

  • Cervix: Thins from $2\text{ cm}$ thick down to paper-thin (like pulling a tight turtleneck sweater over a head).

  • Vagina and Pelvic Muscles: Stretch and help steer the baby's head into the right direction.

Passenger (The Baby)

• The Baby's Head:

  • The baby's skull bones are not joined together yet. They are separated by soft lines called sutures and soft spots called fontanelles.

  • Molding: The skull bones can slightly slide over one another during birth to make the head smaller and help it fit through the pelvis.

• Baby's Posture (Attitude):

  • Best posture (Full Flexion): The baby curls up into a ball with the chin tucked tightly against the chest. This presents the smallest possible head diameter ($9.5\text{ cm}$) to the birth opening.

  • Extension: If the baby's head is tilted backward, a much wider part of the head tries to enter, making delivery harder.

• Baby's Direction (Lie):

  • Longitudinal Lie: The baby's spine runs parallel to the mother's spine (up and down); this is the normal way to deliver vaginally.

  • Transverse Lie: The baby is lying sideways ($90^\circ$ angle); a vaginal birth is impossible and requires a C-section (surgical birth).

• Presentation (Which Part Comes First):

  • Cephalic (Head-first): Occurs in about $95\%\text{ to }96\%$ of births; the safest and most common.

  • Breech (Bottom or feet first): Happens in $2\%\text{ to }3\%$ of births. Frank breech has legs pointed up toward the face; complete breech is sitting cross-legged; footling breech has one or two feet pointing down. Many breech babies need a C-section for safety.

  • Shoulder: Baby is sideways with a shoulder presenting; needs a C-section.

• Baby's Position Coding:

  • Doctors use three letters to show where the baby is facing (for example, LOA means Left Occiput Anterior, where the back of the baby's head faces the front-left of the mother). LOA and ROA are the easiest positions for delivery.

• Station (How Far Down the Baby Is):

  • Measured against the narrowest point of the mother's pelvis (the ischial spines):

    • $0\text{ cm}$ Station: The baby's head has reached the narrowest point (called "engaged").

    • Minus numbers ($-1\text{ to }-4\text{ cm}$): Baby is still higher up in the pelvis.

    • Plus numbers ($+1\text{ to }+4\text{ cm}$): Baby is moving down closer to being born.

The Baby's Steps Through the Pelvis (Cardinal Movements)

As the baby moves down, it takes specific twists and turns:

1. Engagement: The baby's head enters the pelvis at station $0\text{ cm}$.

2. Descent: The baby continues moving downward through the birth canal.

3. Flexion: Resistance causes the baby to tuck its chin tightly against its chest to show the smallest head size ($9.5\text{ cm}$).

4. Internal Rotation: The baby turns its head $45^\circ$ to face the mother's back so it can fit through the widest part of the pelvic bones.

5. Extension: The head slips under the pubic bone and tilts backward, allowing the forehead, nose, and chin to come out.

6. External Rotation (Restitution): The baby's head untwists $45^\circ$ to line back up with the shoulders inside.

7. Expulsion: The shoulders slip out (top shoulder first, then bottom shoulder), and the rest of the baby slides out quickly.

Powers of Labor

• Primary Powers (The Womb's Involuntary Squeezes):

  • The mother cannot control these contractions; they happen automatically.

  • Wave Shape: Each contraction builds up (increment), reaches a strong peak (acme), and then relaxes (decrement).

  • Rest Breaks: The resting time between contractions gives the mother a break and lets fresh blood and oxygen flow back to the baby.

• Secondary Powers (Pushing):

  • Once the cervix is fully open ($10\text{ cm}$), the mother uses her abdominal stomach muscles to push down, helping the contractions move the baby out.

Maternal Positions and Movement

• Why Upright Postures Help:

  • Staying upright (walking, sitting, squatting, or kneeling) lets gravity help pull the baby down.

  • It takes pressure off the tailbone, opening up the pelvis to make more room.

• Drawbacks of Lying Flat on the Back:

  • Lying flat on the back presses the heavy womb against major blood vessels, which can lower the mother's blood pressure and reduce oxygen flow to the baby.

• Comfort Tools:

  • Squatting: Opens up the pelvic outlet.

  • Hands-and-Knees: Relieves back pressure and helps a baby facing the wrong way turn around.

  • Birth Balls (Peanut Balls): Placing a peanut-shaped ball between the legs helps open the hips and shortens labor, even if the mother has an epidural numb block.

• Proven Benefits of Moving Around:

  • Shorter labor time.

  • Less need for pain medication or medical tools (like vacuums or forceps).

  • Fewer deep tears and lower chances of needing a surgical C-section.