Prematurity Module

AnS 536

Spring 2015

What is Prematurity?

Prematurity is defined as less than 37 weeks of gestation in humans

Prior to 32 weeks is considered a very premature birth

Less than 28 weeks is extremely premature

Preterm Labor Occurs prior to expected delivery date Occurs for a variety of reasons

Prelabor rupture of membranes Can lead to amnionitis

Methods to prevent labor Stop /delay onset of pre-mature births Do not guarantee a healthy infant

Planned interventions to terminate pregnancy Serious maternal illness Problems affecting fetal well being or growth

Preterm Labor Preterm labor prevention:

Social measures Ad campaigns increasing awareness

Smoking Sexually transmitted diseases

Physical measures At home uterine-activity monitoring Bed rest Cervical assessment

Surgical measures Cervical cerclage

Preterm Labor

Preterm labor prevention cont…Pharmacological agents

Betamimetic drugs Stop uterine contractions in active labor Most widely used among other labor-inhibiting agents

Inhibitors of prostaglandin synthesis Strong and practical use in preventing labor

Antibiotics Some use in preventing early labor in women with

bacterial vaginosus

Preterm Labor Types of preterm births

Antepartum death Lethal malformations

Fetal outcome cannot be changed, vitality of mother is important

Multiple pregnancies 50% of all multiple pregnancies result in premature delivery

Elective deliveries Maternal and/or fetal pathology

Preclampsia Antepartum hemorrhage Intra-uterine growth restriction

Antepartum death and lethal malformations 10-15% of all premature births Almost 50% of total perinatal mortality This form is unsavable Infant dies before labor or has

malformations that are incompatible with life Maternal well-being is a large factor Ethical problems come in to play

Multiple Pregnancy

Almost half of multiple births occur prematurely

Multiple births are 15 times more likely to be associated with premature delivery

Multiple births make up 20% of all premature cases

Elective Delivery

Planned obstetric decision Complications during pregnancy within the

mother or the fetus Not necessarily premature infants

Maternal and Fetal Pathology

Eclampsia Antepartum hemorrhage Intra-uterine growth restriction Spontaneous preterm labor

Route for Delivery

Main decision for premature infants Vaginal or Cesarean Section Breech much more common in preterm Safer for premature infants to use C-section

Mostly planned deliveries Premature baby is more susceptible to

compress from the pelvic region than a term baby They have a softer skull

Preterm Birth

Physiological consequences Infant’s body system are not prepared to

function on their ownNumerous conditions that result from

prematurity can be treated Depending upon extent of prematurity,

morbidity rate may be great

Preterm Birth Preterm birth is the leading cause of neonatal mortality

Lack of development of body systems is underlying cause

Concerns: Increased morbidity and mortality Intraventricular hemorrhage (IVH)Periventricular leukomalacia (PVL)Cerebral palsyNecrotizing enterocolitis (NEC)Retinopathy of prematurity (ROP)Respiratory distress syndrome (RDS)

Preterm Birth Complications

Respiratory distress syndrome Affects over 50% of premature infants One of leading cause or mortality and

morbidity Ventilator needed in some cases Use different techniques to speed up

pulmonary maturation or assist lung function

Preterm Birth Complications

Corticosteroids betamethasone and dexamethasone

Reduce risk of RDS by 40-60% Speeds up lung maturation Max effect more than 24 hr prior to birth

within 7 days of administration Risks to corticosteroids

Increased susceptibility to infection

Renal System

Decreased ability to maintain blood pressure

Difficult time regulating electrolyte and water balance

Neurological

Developmentally behind slightly Intraventricular hemorrhage

Blood vessels of brain not fully developed Premature infants at a much higher risk Increase risk if other problems No prevention

Hydrocephalus Fluid accumulation in the brain

Neurological

Periventricular leukomalaciaContributing factors:

Premature infant brains very fragile Lack of oxygen Early rupture of fetal membranes Infection inside the uterus

No treatment for this condition

Thermoregulation

Tend to lose body heat rapidly Less stored fat At high risk to hypothermia

Leads to breathing problems and low blood glucose

Use available energy for heatHypoglycemiaDecreased stores of glycogen

Gastrointestinal and Metabolism

Immature systems Necrotizing enterocolitis

Cells in bowel are injured Infants fed only breast milk have lower risk

Spontaneous intestinal perforation

Immunity

Increased susceptibility to infection through childhood

Risk of bacterial infectionProlonged intensive careNICU environment

Immunoglobulin G deficiency at birth

Immunity cont.

Slower development of innate immune defense

Prematurity affects all aspects of immunity Immune signaling Link between adaptive and innate immunity

Limited neutrophil precursor pool Neutropenia

Increase bacterial infections

Long Term

Cerebral palsy 40-50% of patients were born prematurely Affects movement and muscle tone Results from CNS damage

Poor circulation Insufficient oxygen and nutrient supply Neural infection

Impaired cognitive skills Lag behind full-term babies in mental development More likely to have a learning disability

Long Term Cont.

Vision problems Retinopathy of prematurity

Blood vessels swell and overgrow in the light sensitive layer of the nerves of the retina

Retinal scarring Retinal detachment

Possible blindness

Hearing problems Increased risk of hearing loss

Long term cont.

Dental problems Delayed tooth eruption Tooth discoloration Improper alignment of teeth

Behavioral and psychological problems More likely to develop problems Attention deficit hyperactivity disorder (ADHD) Depression or anxiety Interaction issues

Long term cont.

Chronic health issues InfectionsAsthmaFeeding problemsSudden infant death syndrome

Possible risk of diabetes and cardiovascular disease

Preterm Birth Cerebral palsy

Condition where infants are unable to control muscle movement

Muscles become tight and uncontrolled No treatment for this condition

Necrotizing enterocolitis Occurs 3 to 7 days after onset of feeding Premature infants react abnormally to diet Bowels become inflamed and spontaneously necrose Treatment:

Surgical treatment if bowel is perforated Feedings are withdrawn Contents of stomach are suctioned out

Developmental Outcomes for Premature Infants Rate of premature births has increased

↑ by 29% from 1981 to 2002 Survival rate of premature infants reaching

adulthood has also increased Can be severe consequences of prematurity