Labor, Delivery & Changes after Birth

Module B – Part II

Objectives

• Differentiate between the stages of labor and delivery and list the significant complications that can occur during each.

• List and differentiate between the abnormal situations that can occur during the gestational period and state how they may impact delivery and post-uterine life.

• Identify and describe the factors that cause changes in cardiopulmonary anatomy and physiology during the first minutes of post-uterine life.

Maternal History

• GravidaGravida – Total number of pregnancies (including therapeutic and spontaneous abortions).• Primigravida (first pregnancy)• Multigravida (more than one pregnancy)

• ParityParity (ParaPara) – Total number of live born (delivered past 20 weeks).• The condition of having carried a

pregnancy to a point of viability regardless of outcome.

Maternal History

• Spontaneous Abortion (SAb)

• Therapeutic Abortion (TAb)

• Examples:• Gravida 1, Para 0 • Gravida 1, Para 1• Gravida 1, Para 2• Gravida 1, Para 3• Gravida 5, Para 4, SAb 1

Parturition

• ParturitionParturition: The process of giving birth.

• 5 events to the birthing process• Rupture of membranes.• Dilation of Cervix.• Contraction of the uterus.• Separation of the placenta.• Shrinking of the uterus.

Labor

• Stage I: Onset of regular contractions to full dilation and effacement of the cervix.• Three phases: Early, Active, Transition.

• Stage II: Delivery of the fetus.

• Stage III: Delivery of placenta.

• Recovery Stage: Shrinkage of uterus and return to normal homeostasis.

False Labor

• False labor • Contractions are called Braxton-Hicks.• Rhythmic and fairly mild compared to true

contractions.

Stage I of Labor

• Effacement & dilation begins at the first contraction.• Cervix stretches and thins (effacement).• Widening of the cervix (dilation).

• Effacement is measured as a %.• 100% effacement means the cervix is

imperceptible against the uterine wall.

• Dilation is measured in centimeters.• Full Dilation is 10 cm.

Stage II of Labor• Delivery of the fetus

• Uterus differentiates into a thick muscular upper portion and a thin lower section.

• The descent of the fetus is aided by contraction of the abdominal muscles and diaphragm.

• 95% of deliveries occur in the head – down or vertex position.• Head turns to a face-down position.

• Umbilical Cord is clamped.

Vertex Position

Stage III of Labor

• Expulsion of the placenta.• 5 - 45 minutes

• After delivery of the fetus, the uterus continues to contract, tearing the placenta from its walls.

• May be facilitated with breast feeding and the secretion of oxytocin.• Increase uterine contractions.

Premature Labor

• Incidence of premature labor.• 40% in high risk patients.

• Incidence of premature delivery.• 20% in high risk patients.

• TocolysisTocolysis• Process of stopping labor.• Beta sympathomimetic (adrenergic) drugs

• Relax smooth muscle in uterine wall• Terbutaline & Ritodrine

• Magnesium Sulfate

Tocolysis

• Indications for Tocolysis• Baby must be between 20 – 36 weeks

gestation OR Placenta Previa is present.

• True Labor (3 contractions in 20 minutes). • Cervix cannot be dilated more than 4 cm &

effaced more than 50%.• Intact amniotic membranes.• No fetal distress.• Informed consent by the mother.

Dystocia

• Difficult Labor.• Stage I & II exceed 20 hours.• Stage II exceeds 2 hours in primigravidas and

1 hour in multigravidas.• As length of labor increases , morbidity and

mortality increase for three main reasons:• Abruptio placenta (premature separation of placenta

from uterine wall).• Compression of the umbilical cord.• Risk of infection increases after membrane rupture.

Causes of Dystocia

• Uterine dysfunction.

• Abnormal fetal presentation.

• Excessive fetal size.

• Hydrocephalus.

• Abnormality in size or shape of the birth canal.

Fetal Presentations• Any position other than

vertex.• Complete Breech

• Feet, legs and buttocks all present together

• Incomplete Breech• Footling

• Frank Breech• Buttocks is the presenting part

• Transverse lie • Other presentations

• Brow, face, shoulder

COMPLETE

FOOTLING FRANK

Types of Breech Deliveries

FACE

BROW

Other Delivery Presentations

Transverse Lie

• Usually requires C-Section

Fetal Skull

• The fetal skull is not a solid structure as in an adult.

• Several bony plates separated by sutures.

• During delivery, the plates overlap, decreasing the size of the fetal skull.

• In face/brow presentations the plates cannot overlap & the head must pass through at full size – severe facial edema occurs.

Problems with the Umbilical Cord

• Prolapsed Cord• Umbilical cord passes through

the cervix into the birth canal ahead of the presenting part

• Common in breech presentations & multiple births

• Occult Prolapse• Compression of the cord in

the uterus where the cord is not visible.

• Both type can lead to asphyxia

Placental Abnormalities• The embryoblast normally attaches itself

near the upper portion of the uterine cavity.

• If implantation occurs in the lower portion of the uterus, it is called placenta previa.• Low implantation – does not cover cervical

opening.• Partial placenta previa.• Total placenta previa.

Types of Placenta Previa

Partial

Abruptio Placentae

• Abruptio Placentae – is premature separation of a normally placed placenta from the uterine wall.• Usually causes labor to begin.• Maternal mortality is 2-10%.• Fetal mortality approaches 50%.• Mortality rates are attributed to blood loss.• Most common cause is maternal hypertension

(preeclampsia).

Abruptio Placentae• Placental separation

can be partial or complete

• If no bleeding is seen • Concealed hemorrhage

• Bleeding from the vagina • Apparent hemorrhage• Maternal hypovolemic

shock

Cesarean Delivery

Cesarean Delivery

• aka C-section

• Indications:• Prior C-section• Breech presentation• Fetal Distress

• Complications:• Cutting of placenta,

cord or fetus.

• TTN often occurs (failure to adequately clear lung fluid.

Multiple Gestations

• Twins: 1 in 99 births• Other multiples more rare:

• In 2000, 6,742 triplets, 506 quadruplets, 77 quintuplets or more.

• Van Houten sextuplets• Born on 3 different days (1/7, 1/16, & 1/17/2004)• All doing well in Grand Rapids

• Higher risk to mother.• Higher incidence of premature labor.• 2nd twin more compromised.• Boys worse than girls.

Adaptation to Extrauterine Life

• Fetal breathing movements actually occur in utero.• As early as week 18; usually within last 10 weeks.

• Multiple “reasons” for initiation of the first breath:• Asphyxia: Increased PaCO2, decreased PaO2,

and decreased pH all lead to stimulation of chemoreceptors and a gasp.

• Recoil of thorax. • Environmental changes:

• Initiation of the cry reflex caused by entering a cold, loud and bright environment.

• Tactile stimulation.

The First Breath

• Initial pressure necessary to overcome ST can be as high as –100 cm H20.

• Pressure decreases with each succeeding breath as FRC is established.

• As the alveoli deflate, surfactant prevents the alveoli from collapsing.

• Each breath requires less energy and becomes less difficult.

First Breaths

Egan

Fig. 7-6 p. 145

Changes in Circulation

• Umbilical Cord is clamped.• Blood flow to placenta is stopped and blood

perfuses the lower extremities.• High vascular resistance develops and the high

pressure increases back to the left side of the heart.

• This helps to close the foramen ovale.

Pulmonary and Systemic Vascular Resistance

• The first breaths decrease pulmonary vascular resistance (PVR) due to the rise in PaO2.

• This decreases the pressure in the pulmonary artery, right heart & pulmonary capillaries.

• Complete reversal of heart pressures & vascular resistance has occurred.• PVR is low, SVR is high.• Left Atrial Pressure > Right Atrial Pressure

Ductus Arteriosus• During the last few weeks of gestation,

smooth muscle develops surrounding the ductus arteriosus.

• The ductus has stayed open due to the presence of prostaglandins.• Prostaglandins are inhibited by high PaO2. • With first breath and increasing PaO2 closure of

the ductus arteriosus occurs.• If PaO2 should fall, the ductus arteriosus may

reopen. This is called a Patent Ductus Arteriosus (PDA).

Ductus Venous & Umbilical Vein

• With the umbilical cord clamped, blood no longer flows through the umbilical vein, arteries and ductus venosus.• These vessels constrict and become

ligaments.