Prematurity
Labor, Delivery
Muruvet Elkay, MD
PL-II
12/16/2005
Objectives
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Epidemiology
Risk factors
Infection
Role of antenatal steroids
Complications
Management
Preterm Labor
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Preterm labor (PTL): Presence of
contractions which cause progressive
effacement and dilatation of the cervix
between 20 and 37 weeks’ gestation.
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Preterm birth (PB): Occurs in 6-8% of
pregnancies. The incidence has remained
stable for more than 25 years.
Ref: eMedicine Sep 22, 2004: Preterm Labor: Article by Edward R. Newton, MD
Terms Related to Prematurity
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Premature infant: An infant born before 37
weeks of estimated GA.
Low birth weight (LBW): BW<2,500 g
Very low birth weight (VLBW): BW<1,500 g
Extremely low birth weight (ELBW):
BW<1,000 g
Chronologic or birth age: Time since birth.
GA: Estimated time since conception;
postconceptional age.
Corrected age: Age corrected for
prematurity.
Ref: David E. Trachtenbarg etal. American Family Physician 1998; 57 (9): 1-11
The Epidemiology of Preterm
Birth
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Racial differences in the rate of preterm
LBW
VLBW
African-American women 13.0%
3.1%
Asian-Pacific Islanders
7.3
1.0
Native Americans
6.8
1.2
Whites
6.5
1.1
Hispanics
6.4
1.1
In a twin, triplet or higher order multiple
gestation: 23 % of LBW infants
Ref: Jay D. Iams, Clin Perinatol 30 (2003) 651-664.
US Incidence of Preterm
Birth 1992-2002
Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
Neonatal Morbidity and Mortality
by Gestational Age
GA, wks Survival
24
25
26
27
28
29
30
31
32
33
34
40%
70%
75%
80%
90%
92%
93%
94%
95%
96%
97%
RDS
IVH
Sepsis
NEC
70%
90%
93%
84%
65%
53%
55%
37%
28%
34%
14%
25%
30%
30%
16%
4%
3%
2%
2%
1%
0%
0%
25%
29%
30%
36%
25%
25%
11%
14%
3%
5%
4%
8%
17%
11%
10%
25%
14%
15%
8%
6%
2%
3%
Intact
survival
5%
50%
60%
70%
80%
85%
90%
93%
95%
96%
97%
Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
Hospital Charges by Gestational
Age of Delivery
GA (n)
Mother Charges
Baby Charges
Total Charges
25-26 weeks (40)
$11,102
$192,882
$203,994
27-28 weeks (58)
$9,765
$160,234
$169,999
29-30 weeks (76)
$10,882
$70,684
$81,566
31-32 weeks (127) $9,500
$36,991
$46,490
33-34 weeks (208) $9,016
$15,450
$24,447
35-36 weeks (240) $6,091
$8,484
$14,457
>36 weeks (204)
$2,276
$6,586
$4,310
Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
Etiology of Preterm Birth
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Physician-initiated birth (indicated PB):
a. Pre-eclampsia 40%
b. Fetal distress 30%
c. IUGR 10%
d. Abruption placenta or placenta
previa 10%
e. Fetal death 5%
Spontaneous PB:
a. Preterm labor (PTL)
b. Preterm premature rupture of
membranes (PPROM)
Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600
Risk Factors for PTL and
PPROM
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PTL
Previous PB
Low body mass
Poor weight gain
Heavy work load
Uterine
abnormalities
Drug abuse,
smoking
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PPROM
INFECTION
Uterine distension
Cervical incompetence
African-American
Low socioeconomic
class
Drug abuse, smoking
Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
The Strong Association Between
Infection and Preterm Birth
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Incidence of subclinical histologic
chorioamnionitis:
50%
24 to 28 weeks
10%
>37 weeks
The smaller the fetus, the more likely the
chorioamnion cultures are positive:
80%
<1000 g
30%
>2500 g
Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
Relation of Infection and Preterm Birth
Genome
Uteroplacental Insufficiency
Maternal Stress
Fetal Stress
↓Progesterone Inhibition
Bacteria, Virus, Protozoa
Infection:Leukocyte Response
↑TOLL 4 Receptors
Cytokine Cascade:↑TNF, ↑IL6, ↑ IL8, etc
Genome
Decidual Activation
Phospholipase A, prostaglandins, lysolethecin, mettaloproteinases, collagenases, elastases..
Phospholipase A, prostaglandins, lysolethecin, mettaloproteinases, collagenases, elastases..
Preterm Labor
Rupture of Membrane
Cervical Incompetence
PRETERM BIRTH
Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600
Risk Factors for Infection-Related
Preterm Birth
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Historical:
Idiopatic PL, PROM
History of UTI and STI
Behavioral:
Unintended pregnancy
Unmarried
Multiple partner
Signs and symptoms:
Vaginal discharge
Dysuria, dyspareunia
Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
Prophylactic Antibiotics to Prevent
Preterm Birth
GBS
 Incidence of vaginal GBS- 20-25%.
 No association between vaginal GBS and
PB.
 Prophylactic antibiotics are not indicated
for recto-vaginal colonization of GBS.
 Antepartum treatment of GBS in urine.
Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
Therapeutic Antibiotics for InfectionRelated Preterm Birth
GBS: Antepartum treatment of all the women
with the risk factors:
 Maternal colonization
 Previous infant who had GBS sepsis
 Antenatal GBS asymptomatic bacteriuria
 ROM >12 hrs
 Intrapartum fever (probable chorioamnionitis)
 GA < 37 wks
Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
Antibiotics for Inhibiting PL with
Intact Membranes
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Antibiotics are not recommended.
Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
Antibiotics for PPROM
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Risk of chorioamnionitis- 20% between 28
and 34 weeks.
Antibiotics are recommended in nonlaboring
women.
Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
Chorioamnionitis
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Inflammation or infection of the placenta,
chorion, and amnion.
Histologic, subclinical chorioamnionitis:
>50% of preterm deliveries
<20% of term deliveries
Clinical chorioamnionitis:
5% to 10% of preterm deliveries
1% to 2% of term deliveries
Ref: Rodney K Edwards: Obstet Gynecol Clin N Am 32 (2005) 270-296.
Clinical Chorioamnionitis
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Most frequent identifiable cause of PL.
<30 weeks 50%
PPROM
40%
PL with intact membranes 30%
Maternal fever in the peripartum 10% to 40%
Polymicrobial.
Ref: Rodney K Edwards: Obstet Gynecol Clin N Am 32 (2005) 270-296.
Clinical Chorioamnionitis
Diagnostic criteria:
Maternal fever of greater than 100.4 F and at
least 2 of the following conditions:
 Maternal leukocytosis (>15,000 cells/cubic
mm)
 Maternal tachycardia (>100 bpm)
 Fetal tachycardia (>160/bpm)
 Uterine tenderness
 Foul odor of the AF
Ref: Rodney K Edwards: Obstet Gynecol Clin N Am 32 (2005) 270-296.
Neonatal Outcomes of
Chorioamnionitis
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Intraventricular hemorrhage
Periventricular leukomalacia
Cerebral palsy
Increased rates of bacteremia
Clinical sepsis
Increased mortality
Low Apgar scores
Hypotension
The need for resuscitation at the delivery
Neonatal seizures
Ref: Rodney K Edwards: Obstet Gynecol Clin N Am 32 (2005) 270-296.
Antenatal Steroids
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Indicated in the delivery of a fetus at 24-34
weeks’ gestation in the absence of clinical
infection.
Delay of delivery- A minimum of 12 hours.
Duration of benefits-7 days or more?
Betamethasone or Dexamethasone?
Reduces the incidence of IVH and NEC.
An adverse impact of multiple courses on
fetal growth and development.
Ref: eMedicine Sep 22, 2004: Preterm Labor: Article by Edward R. Newton, MD.
Benefits of Antenatal Steroids
Last 7 Days or More?
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197 neonates
Group I: 98 delivered within 7 days
Group II: 99 delivered more than 7 days
Group I: Lower incidence of receiving
respiratory support more than 24 hrs.
No significant differences between the groups
in other measures of neonatal morbidity.
Ref: Alan M. Peaceman et al. Am J Obstet Gynecol 2005; 193, 1165-9.
Betamethasone or Dexamethasone
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201 preterm singleton infants
GA between 24 and 34 weeks
Neurodevelopmental outcome at 2 years
corrected age
Results: Multiple antenatal courses of
DEXAMETHASONE associated with an
increased risk of leukomalacia and 2-year
infant neurodevelopmental abnormalities.
Ref: Spinillo A et al. Am J Obstet Gynecol 2004;191 (1): 217-24.
Complications of Premature
Infants
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RDS
IVH
NEC
ROP
CLD (BPD)
Infection
Anemia
PDA
Apnea
Cryptorchidism
Inguinal hernia
Umbilical hernia
SGA and IUGR: Are They
Synonymous?
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SGA: Birth weight below the 10th percentile
for GA or > 2 standart deviations below the
mean for GA.
IUGR: A process that causes a reduction in
an expected pattern of fetal growth.
1. Symmetric IUGR
2. Asymmetric IUGR (head-sparing IUGR):
All IUGR infants may not be SGA (Ponderal
index).
Ref: Utpala G et al: Pediatr Clin N Am 2004;51: 639-654.
Neonatal Complications of
IUGR or SGA
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Metabolic disorders: Hypoglycemia,
hypocalcemia
Hypothermia
Hematologic disorders: polycytemia
Hypoxia: birth asphyxia, meconium
aspiration, persistent fetal circulation
Congenital malformation
Ref: Utpala G et al: Pediatr Clin N Am 2004;51: 639-654.
Long-term Complications of IUGR
or SGA
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Cardiovascular disease
Hypertension
Type 2 diabetes
Ref: Utpala G et al: Pediatr Clin N Am 2004;51: 639-654
A Premature Infant may be a SGA or
IUGR Infant Also- Double Jeopardy!
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An adverse outcome resulting from both
immaturity and deficient intrauterine
growth.
Increased risk for mortality and major
neonatal morbidities, including RDS, BPD,
ROP, and NEC.
Intensified complications of prematurity
by the effect of suboptimal fetal growth.
Ref: Rivka H. Regev et al: Clin Perinatol 2004; 34: 453-473.
Management of Premature
Infants
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Delivery room
management
Temperature and
humidity control
Fluids and
electrolytes
Blood glucose
Calcium
Nutrition
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Respiratory support
Surfactant
PDA
Transfusion
Skin care
Other special
considerations
THANK YOU
Special Thanks to Dr. Manuel V. and Colin Bird MSIII