THE LATE PRETERM
INFANT
Ronette Santos-Chua, MD
Neonatology
October 18, 2011
Objectives
Define “late preterm”
Review the epidemiology of late preterm and develop
awareness of the trend
Appreciate the increased risk for mortality and morbidity
Identify the co- morbidities and potential complications of
the late-preterm infant
Understand the prognosis and neurodevelopmental
implications of late preterm infants
Review recommendations and strategies for the care of the
late-preterm infant
Understand the need to counsel the parents of the latepreterm infant
Terminology
“Near-term” infants
– “almost term” therefore almost fully mature
– Reassuring term
Recommended to change to “late preterm”
– Better reflects higher risk of complications
“Late preterm” infant (AAP, ACOG and NCHS)
– 34 0/7 to 36 6/7 weeks of gestation (239 - 259 days)
"Optimizing Care and Outcome of the Near-Term Pregnancy and the Near-Term Newborn
Infant“ Workshop sponsored by the National Institutes of Health , 2005
Preterm birth by gestational age
Percentage distribution preterm births, United States, 2004.
Epidemiology
1 in 8 babies is born
prematurely in the
United States
Late preterm infants
– Account for more
than 70% of these
preterm births
Late preterm births
US, 2007
Late preterm is between 34 and 36 weeks gestation.
Source: National Center for Health Statistics, final natality data. Retrieved October 4,
2010, from www.marchofdimes.com/peristats.
Late preterm birth : US vs.
Indiana
USA
Indiana
Singletons : US vs. Indiana
USA
Indiana
Epidemiology
Multiple births
– Twins
60% born prematurely
Mean GA 35.2 weeks
1990 - 22.3/1000
2006 – 32.1/1000
– Triplets
93% born prematurely
Mean GA 32 weeks
1990 – 23/1000
2006 – 33.7/1000
Epidemiology
Late Preterm Birth Rates,* by Plurality --- United States, 1990, 2000, and 2006
http://www.cdc.gov/nchs/data/databriefs/db24.pdf
Martin JA, Kirmeyer S, Osterman M, Sheperd RA. Born a bit too early: recent trends in late preterm
births. NCHS data brief, no 24. Hyattsville, MD: US Department of Health and Human Services,
National Center for Health Statistics; 2009.
Multiples : US vs.Indiana
USA
Indiana
Temporal change prematurity
Rates (Panel A) and relative temporal changes since 1989 (Panel B) of preterm birth <37 weeks (all races), as well as those resulting from
ruptured membranes, medically indicated, and spontaneous preterm birth: United States, 1989 through 2000.
Reproduced with permission from: Ananth, CV, Joseph, KS, Oyelese, Y, et al. Trends in Preterm Birth and Perinatal Mortality Among
Singletons: United States, 1989 Through 2000. Obstet Gynecol 2005; 105:1086. Copyright ©2005 Lippincott Williams & Wilkins
.
Why more late preterm births?
Increased fetal surveillance and
interventions
Attempts to prevent stillbirths
Accuracy of gestational age assessment
Multiple gestations / ART
Maternal health and demographics
Maternal autonomy
Physician practice patterns, legal risks
Contributing factors
Advancing maternal age
– Mothers > 30 years
Highest level in more than four decades
Inaccurate gestational dating
– Early fetal ultrasound
– History
– Fundal height
Increasing maternal obesity
– Maternal diabetes
– Maternal hypertension
– Multifetal pregnancy
Risk factors for LPTB
Prior PTB
Race
Maternal Age
Tobacco use
IUDE
Infection
Maternal chronic disease
Pregancy complications
Multiple gestation
Iams JD, Clinics in Perinatology 2003
ART
Preventing fetal mortality?
Birth Preliminary Data for 2009
National Vital Statistics Report
Vol 59, No 3
Dec 2010
So what’s the big deal?
Mature in appearance
Birth weight 2-2.5 kg
Most are stable in delivery room
Most are cared for in well-baby nursery
Morbidity
7 times greater in LPTI
– 22% vs. 3%
10-14 times greater with other risk factors
–
–
–
–
–
Maternal HTN
GDM
Antepartum hemorrhage
Infections
Chronic maternal conditions
Shapiro-Mendoza, Pediatrics 2008
Morbidity
Temperature instability
– 10% (0%)
Hypoglycemia
– 15% (6%)
RDS
– 29% (4%)
Apnea
– 6% (<0.1%)
Jaundice
– 54% (38%)
Feeding difficulties
– 32% (7%)
Shapiro-Mendoza, Pediatrics 2008
Engle W Clinics in Perinatology 2008
Morbidity
Morbidity
LPTI have longer hospitalization
– 8.8 days vs. 2.2 days
There is a ten-fold higher cost of care
– $26,054 vs. $2,061
With 8% LPT birth rate > $800M/yr in US
Mclaurin, Pediatrics 2009
NICU Admissions
Respiratory distress
interventions
Fetal lung fluid physiology
Lungs are filled with fluid in utero
– 4-6ml/kg at mid-gestation
– 30-50 ml/kg near term
Fluid moves up trachea and is swallowed
or moves into amniotic fluid
Volume of lung fluid mediated by larynx
– 1cm of water pressure
– Keeps lungs distended
Fetal lung fluid physiology
Fluid begins to decrease a few days prior
to spontaneous onset of labor
– 25ml/kg to 18 ml/kg
With onset of labor epinepherine activates
the switch within the lungs to change from
net secretion to net reabsorption.
Vaginal squeeze and Starling forces play a
small role
Fetal lung fluid clearance
Hypothermia
10% may experience temperature
instability
Less white adipose tissue
– Insulation
Less brown adipose tissue
– Heat generation
Increased heat loss
– Higher SA:BW ratio
Hyperbilirubinemia
Risk of significant
hyperbilirubinemia requiring
phototherapy
– Term
10.5%
– Late preterm
25.3%
Levels peaked later
– 5-7 days vs. 3-5 days
Longer hospital stays
Readmissions
Sarici et al, Pediatrics 2004
Hypoglycemia
Increased risk vs. term counterparts
–
–
–
–
Decreased glycogen stores
Decreased amounts of brown fat
Blunted ketone response
Inadequate intake
15.6% vs. 5.3%
– OR 3.3 (1.1-12.2)
Nearly 2/3 with hypoglycemia required
supplemental IVF to correct
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Neurodevelopmental outcome
At 35 weeks
– Weight = 65% that
of term infant
– Fewer sulci
These findings
may increase
vulnerability to
long-term injury
Neurodevelopmental outcome
Increased risk for developmental delay
– Early childhood
4.2% vs 3%
– 3 years of age
4.5% vs 3.9%
– 4 years of age
7.4% vs 6.6%
Cerebral palsy
– Three times the risk vs. term counterparts
Poorer school performance
NICHD showed no consistent differences
– 4-14 years
Morse, Pediatrics, 2009
Petrini J of Pediatrics, 2009
Chyl J of Pediatrics, 2008
Gurka Arch Ped/Adol Med, 2010
Neurodevelopmental outcome
Neurodevelopmental outcome
Percentage of live births and infant deaths by period of gestation in
weeks: United States, 2005
Reproduced from: Matthews, TJ, MacDorman, MF. Infant mortality statistics from the 2005
period linked birth/infant death data set. Natl Vital Stat Rep 2008; 57:7. Available at:
http://www.cdc.gov/nchs/data/nvsr/nvsr57/nvsr57_02.pdf (Accessed March 27, 2009).
Does mode of delivery affect
the LPTI?
Amon, 2009
– >1million births reviewed
– Mortality
3.25 x higher all modes of delivery
Vaginal deliveries
– 6.1/1000 (2.1 term)
Cesarean section
– 12.9/1000 (3.3)
– Without labor 13.4/1000 (8.1)
– 46% of LPTI were born by C/S or induction
Cesarean section
Elective C/S vs. vaginal birth
– Increased risk of NICU stay >7 days
OR 2.11 (1.75-2.55)
– Cephalic presentation
Mortality 1.7 fold higher
– Breech presentation
Reduces mortality
Engle, Clinics in Perinatology, 2008
Villar, BMJ 2007
ACOG Committee Opinion
#404
Late-preterm infants often are mistakenly believed to
be as physiologically and metabolically mature as
term infants. However, compared with term infants,
late-preterm infants are at higher risk than term
infants of developing medical complications, resulting
in higher rates of infant mortality, higher rates of
morbidity before initial hospital discharge, and higher
rates of hospital readmission in the first months of life.
Preterm delivery should only occur when an accepted
maternal or fetal indication for delivery exists.
Collaborative counseling by both obstetrician and
neonatal clinicians about outcomes of late preterm
birth is warranted unless precluded by emergent
conditions.
April 2008
Recommendations for care
of LPTI
Infants ≤ 35 weeks should not be sent to or left in
mother’s room unless the following have been
achieved
– Temperature stability
– Stable blood sugars
– Adequate feeding
Determine accurate gestational age
Glucose screening
Bilirubin screening
No early discharge (at least 48 hours)
Vital signs within normal limits for at least 12 hours
prior to discharge
– In open crib
– Appropriate clothing
MINIMUM DISCHARGE criteria for late preterm
infants:
Stable vital signs for 12 hours preceding discharge.
A full 24 hours of successful feeding, either at breast or with a bottle, and
the ability to coordinate suck, swallow and breathing during feeding.
Formal evaluation of breastfeeding documented in the chart by trained
caregivers at least twice daily after birth, to include position, latch and milk
transfer.
The passage of at least one stool spontaneously.
A discharge feeding plan developed and understood by the family.
Dehydration assessment if weight loss is greater than 2% to 3% per day or a
maximum of 7% during the birth hospitalization.
Risk assessment for severe jaundice using gestational and hours of age
nomograms, and appropriate timing of follow-up.
Adequate thermoregulation documented for at least 12 hours.
Absence of medical illness and no physical abnormalities on exam.
Absence of social risk factors.
A follow-up visit arranged for 24 to 48 hours after hospital discharge.
AAP Committee on Fetus and Newborn Policy Statement, Dec. 2007
Statement of Reaffirmation, August 1, 2010
Summary
Late preterm infants (LPTI) are infants 34-36 6/7 wks age of
gestation.
Premature births are here to stay (for now). Over 70% of preterm
births are late preterm.
LPTI vs. term infants have 7x increased risk of morbidity during birth
hospitalization resulting to longer hospital stay and higher medical
costs.
The most common causes of morbidity are hypothermia,
hypoglycemia, respiratory distress, apnea, hyperbili and feeding
difficulties. Readmissions are 2-3x greater in LPTI.
LPTI have increased risk for long-term neurodevelopmental
impairment.
Mortality rate of LPTI is at least 3x greater than term infants.
AAP guidelines for the care of LPTI are in place.
Parents need to be made aware of these risks just as any other
parent at risk of having a preterm infant would be.
Our Stand
<35 weeks or <2000 grams = NICU
35-35 6/7 weeks- NICU observation
(transitional) for 12-24 hours, close
monitoring
36- 36 6/7- admit to the nursery or may
stay with mom but to be watched carefully
for temperature and glucose (feeding)
instability for 6-12 hours
St Elizabeth East NICU
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The End