Late preterm infants are defined as infants born at gestational age from 34 0/7 to 36 6/7 weeks (239 days to 259 days) of gestation. (1) These infants usually have more short-term complications and long term effect on
Neurodevelopment in comparison to term infants.(4-6,14-16,21-26) Large number of late preterm infants need
Admission to NICU and SCN than
term infants due to respiratory problems, feeding difficulties, jaundice,
sepsis, and hypoglycemia. (11-18)
Late preterm infants used to be
called near-term infants because they have nearly the same appearance, size,
and weight of the term infants.(6) In 2005 a workshop held by the National
Institute of Child Health and Human Development (NICHD) changed this concept to
late preterm infants.(10) Those have higher risk of morbidity and
mortality than term babies due to immature
and underdeveloped functions of immunologic, respiratory, neurologic, and
metabolic systems as a result of prematurity.(3,10)
It is crucial to emphasize on the
risks that facing late preterm infants either acutely after delivery during
their hospitalization in NICU and SCN or later due to long term effects on
neurodevelopment. (23, 24)It is important to avoid premature
delivery if there are no fetal risks or maternal indications for early delivery
to avoid the morbidities and complications of prematurity. Another important issue
of preterm delivery that those babies require more respiratory and nutritional
support which increase the financial burden on the hospital. (10)
Limited available studies in our country about
complications and morbidity of late preterm infants. (11)This is the
first study in our hospital concerning the short term complications and mortality
of late preterm infants in comparison to term infants admitted to NICU and SCN
in the same period.
Materials and methods
This retrospective study was carried out in
the NICU and SCN of KHMC over one year duration between January first 2018 and December
31st, 2018. KHMC is the biggest tertiary referral military hospital
in Jordan. Late preterm infants of gestational age from 34 0/7 to 36 6/7 weeks
considered as cases and term infants delivered from 37 0/7 to 41 6/7 weeks of gestation
considered as control group. Gestational age was calculated according to the first
day of last menstrual period and new Ballard score estimation. (1, 28)
each neonate included in this study consent was obtained and signed by his/her
parents and an ethical committee approval from our hospital was granted before
starting the study. Neonates with major congenital abnormalities were excluded
from this study.
Clinical characteristics of each late preterm infant and term
infant admitted to NICU and SCN were recorded. These data included birth weight
at time of delivery, gender, mode of delivery, obstetrical complications
including preeclampsia, premature rupture of membranes(PROM), placenta Previa,
and diabetes either type I and II diabetes or gestational diabetes.
Morbidities and complications were recorded and analyzed for both
late preterm infants and term infants during hospitalization after delivery including
respiratory distress syndrome (RDS), transient tachypnea of newborn (TTN),
hypoglycemia with blood glucose level <40 mg/dl, hypothermia with core
temperature <36.0ºC, feeding problems, neonatal jaundice needed phototherapy
according to American Academy of Pediatrics guidelines (AAP).(27) Culture
proven sepsis either early onset or late onset sepsis, respiratory support
assistance either nasal continuous positive airway pressure (nCPAP) or
ventilator use and surfactant administration. Also, Length of hospital stay and
mortality rate were recorded and analyzed.
statistics were utilized to draw summary measures of central tendency and
frequencies. Means and standard deviations of the dependent variables estimated
and compared among different groups of the study population. An inferential
statistical test was used as the independent t test to test the differences
between two independent group means, the late preterm infants group compared
with the control term infants group. The researchers considered p value ≤ 0.01 significant results.
The total number of babies
delivered was 9195 singleton live births during the study period. 843 babies
out of the total were preterm babies< 37 weeks gestational age included 510 (60%) late preterm babies and 333(40%)
babies preterm <34 weeks gestation (Figure 1). Moreover, 8352 (90.8%) of the total
born babies were term babies, however, 510 babies (5.5%) were late preterm and
333 (3.7%) were preterm <34 weeks gestational age (Figure 2).
Figure 1: The
distribution of 843 premature live births to late preterm infants and preterm
infants <34 weeks gestation
Figure 2: The
distribution of gestational age of 9195 total live deliveries
During the study period, 252 out of 510 (49.4%) late preterm
infants admitted to NICU and SCN while 441 out of 8352 (5.2%) term infants
admitted to NICU and SCN. Clinical characteristics of both groups of babies are
illustrated in (Table I). Birth weight of late preterm infants in grams was
2364 ± 322 (mean ± SD) and for term infants 3131 ± 452. According to babies’
gender, there were 138 males (55%) among late preterm and 228 male (52%) term
infants. Majority of babies admitted to NICU or SCN for both late preterm and
term infants were born by cesarean section (62% vs. 63%).
Maternal risk factors for both groups admitted to NICU or SCN which
are shown in (Table I) were more significant in late preterm infants like
preeclampsia (PET) (9.5% vs. 2.7%, p=0.001) and premature rupture of membranes
(PROM) (8% vs. 0.7%, p=0.000), while placenta Previa (4.7% vs. 1.4%, p=0.000)
and diabetes (8 % vs. 2.2 %, p=0.001).
Neonatal morbidities for both late preterm and term babies during
their hospitalization are shown in (Table II).
The most common cause of NICU and SCN admission for late preterm
infants was RDS (40% vs. 4.5%, p=0.000) while the commonest cause of admission
for term infants was TTN 43% against 35% late preterm. Significant number of term infants admitted
due TTN as a result of higher rate of cesarean section delivery (63%). Late
preterm required respiratory support either by nCPAP (69% vs. 38%, p=0.000) or
by mechanical ventilator (7% vs. 3.4%, p= 0.001). Surfactant administered
mainly for RDS in 12 (4.7%) late preterm babies vs. 3 (0.7%) term babies.
Morbidities observed more often in late preterm infants during
their hospitalization (Table II). Hypoglycemia (6% vs. 0.7%, p=0.001),
Hypothermia developed in 3 late preterm babies (1.2%) while no term baby suffered
from hypothermia. 30% of late preterm and 13.3% of term babies developed
neonatal jaundice required phototherapy. Difficulty with feeding was more prominent
in late preterm infants (37.6% vs. 4.5%). Moreover, Sepsis with positive
culture results was much higher in late preterm (7.2% vs. 1.8%).
The mean length of hospitalization was significantly higher in late
preterm babies compared to term babies (12 days vs. 4 days, p=0.001). Obviously
the mortality rate was much higher in late preterm 15 (6%) against 3 (0.7%)
term babies during the study period (p=0.000). These data are illustrated in
Male, n (%)
Mode of delivery
Cesarean section, n (%)
III: Length of hospital stay and mortality rate of term and late preterm
infants admitted to the neonatal unit
of hospital stay(days)
The study confirmed that late preterm infants who were delivered with a
gestational age of 34 0/7 to 36 6/7 and required admission to NICU and SCN of KHMC
are prone to short term morbidities and have higher mortality rate as reported
by other studies carried out in different countries. (1-9) In this study,
the authors noticed that almost half of the babies who were born late preterm needed
admission (49.4%) due to high number of high risk deliveries transferred to our
tertiary NICU from other peripheral hospitals in the country. In other studies
the number of late preterm infants needed admission was less than the number of
patients in this study as in Tsai M N, et al. study in Taiwan which showed that
36% late preterm infants vs. 2 % term infants required hospitalization. (3)
In Begun L N, et al. study in Bangladesh only 12.9% of late preterm
admitted to NICU. (12)
Before 2005, late preterm infants
were called near term, because of nearly same size and appearance as term
babies, so it was thought that those babies behave as term babies without any
short term or long term adverse consequences due to prematurity.(8,10) The guidelines of American College of
Obstetrics and Gynecology (ACOG) do not recommend delivery before 39 weeks
gestation for elective deliveries if there is no clear obstetric or fetal
indications to avoid possible preterm birth complications.(1,9) Even
babies born early term (37 0/7 through 38 6/7) gestation have some risks
especially if delivered by elective cesarean section mainly due to respiratory
morbidity.(1) The benefits of avoiding preterm delivery should
outweigh the maternal and neonatal risks.
Maternal risk factors and medical
diseases like diabetes, preeclampsia, and placenta previa were more frequent in
late preterm infants which contribute to early delivery. (1, 13-16) PROM was an important factor for preterm
birth. (9,16) Tsai M N, et al. showed that the commonest cause of late
preterm birth is the spontaneous onset of labor and amniotic fluid rupture.(3)
Haroon A, et al. proved that maternal diseases and medical status
like hypertension, diabetes, urinary tract infection and PROM increased the
risk of preterm birth.(16) Because the present study is a retrospective study not
all perinatal records were available to determine exactly the causes of preterm
birth and the adverse effects of maternal obstetrical complications on babies
delivered late preterm. Shapiro-Mendoza C K, et al. indicated that late preterm
birth morbidity was seven fold that of term infants and the risks of preterm
delivery aggravated by maternal medical diseases. (17)
In our study late preterm babies suffered
more neonatal morbidities compared to term babies. Most of late preterm needed
hospitalization due to respiratory distress mainly diagnosed as RDS or TTN as
shown in other studies as a result of immaturity of lung tissues, relative
surfactant deficiency and delayed absorption of lung fluid. (2-6, 18) We
noticed that in the present study large number of late preterm babies diagnosed
as RDS (40%) followed by TTN (35%). In other studies like Savitha M R, et al. 28.2%
of late preterm infants admitted to hospital had respiratory distress and 3.7% of
term infants admitted to hospital due to respiratory distress.(2) In
comparison to other studies, larger number of preterm babies delivered by
cesarean section delivery (62%) which increased the risk of respiratory
distress.(8,9) Antenatal corticosteroids are very effective in
reducing severe RDS and improving survival rate for preterm babies <34 weeks
gestation.(1) Due to large number of late preterm babies admitted to
hospital due to RDS in our study this
guide us to consider giving antenatal steroids in cases of elective late
preterm deliveries in the future to decrease the respiratory morbidities in
these babies. Late preterm babies required more respiratory support than term
babies either by non invasive nCPAP in around one third of cases or invasive
mechanical ventilation in 7%. Surfactant administered more to late preterm
babies 4.7% while just 3(0.7%) term babies required surfactant because RDS is
more common in preterm babies. Surfactant given just to 6 late preterm babies
out of 100 babies with RDS because in our unit we apply nCPAP immediately after
birth for babies with moderate to severe respiratory distress which improved
their lung functional residual capacity and decreased the requirement for
surfactant and invasive ventilation. Late preterm infants are liable for apnea
of prematurity due to immaturity of central nervous system and pulmonary
receptors. (1, 6) They are also more liable in infancy to get
respiratory syncytial virus (RSV) and recurrent wheezy chest in childhood with
the later development of bronchial asthma. (19)
In our study late preterm babies had more feeding
difficulties 37.6% compared to 4.5% term infants as evidenced in other studies due
to immaturity of neurodevelopment system to coordinate sucking-swallowing-breathing
process, respiratory distress which interferes with feeding and longer sleeping
time. (2, 3, 9) The rate of breast feeding is less in late preterm
infants, because large number needs NICU admission with longer duration of
hospital stay so the mothers’ of late preterm neonates require more support for
establishment of breast feeding.
Hypoglycemia is more frequent in late preterm
due to limited stores of glycogen, inadequate glycogenolysis and
gluconeogenesis with impaired ketogenesis.(5,6,18) Hypoglycemia has subsequent adverse neurological effects.(5,8,9)
Hypothermia is more frequent in late preterm babies due to large surface
area and less subcutaneous brown fat.(3,5,8) In our study 3 (3%)
late preterm babies had hypothermia while no term baby experienced hypothermia.
Savitha M R, et al. also found that hypothermia was very significant in late
preterm infants 41 babies vs. 9 term babies. (2)
In our study the risk of jaundice which
required phototherapy was higher in late preterm in comparison to term 30% vs.
13.3%. Same results were shown in other studies.(6,12,13) Jakiel G, et al. showed that jaundice was the most common
morbidity of late preterm babies during their hospital stay affecting around 50%
of cases.(14) Also Visruthan N K, et al. study concluded that late
preterm babies were 3 to 6 times more vulnerable to have jaundice than term
babies.(9) This is due to immaturity of liver enzymes with
subsequent decrease in bilirubin conjugation and excretion.(2,6) Feeding
difficulty and immaturity of gastrointestinal system of late preterm infants
increase the enterohepatic circulation which aggravates the risk of
hyperbilirubinemia in these babies .(5,6,9) They are at high risk
for developing kernicterus. As obtained
in Begum L N. et al. study Jaundice was the most common cause of readmission to
hospital in the neonatal period of late preterm babies. (12) Close
follow up is mandatory in all late preterm babies especially in the neonatal
period to detect jaundice early and start phototherapy if needed to avoid the
risks of kernicterus and the exchange transfusion requirement although it is
Culture proven sepsis in late preterm infants
is about four times term infants in the present study 7.2% vs. 1.8%. Wagh A S,
et al. revealed that nearly the same results of sepsis frequency in the present
study 9.6% vs. 0.9%.(25) Bulut C, et al. reported the incidence of
sepsis of late preterm babies twice that of term babies (21.1% vs. 11.1%). (5)
The higher incidence of sepsis in
late preterm babies is due to immaturity of immune system, longer hospital stay,
and the passage of maternal immunoglobulin IgG antibodies occur after 34 weeks
gestation. (12, 20)
In the present study the length of
hospitalization is much longer in late preterm babies three times that of term
babies as shown in other studies. (2, 6, 12, 26) This will add a
burden to health resources because these babies need extra care during their
hospitalization including nutrition, antibiotics and respiratory support.
Equivalent results were obtained by Bulut C, et al. in their study that the
median duration of hospital admission of late preterm infants was 7 days while
in term babies 4 days. (5) Readmission is more common in late
preterm babies due to jaundice, feeding problems and suspected sepsis. (6,
study, the mortality rate was obviously higher in late preterm in comparison to
term infants 6% vs. 0.7%. Similar results were obtained in other studies. (1-3,
12, 13) Bulut C, et al. reported that the mortality rate as 1.4%, 0.9%, and
0.6% for 34, 35 and 36 weeks gestation late preterm infants respectively while
in term babies 0.3%.(5) The rate of mortality is higher in our
hospital could be due to more high risk deliveries referred to our tertiary
unit for more evaluation and care including preterm deliveries.
Our study has some limitations because of the
retrospective nature of the study. The medical records did not include all the information
about the circumstances of delivery and not all maternal risk factors were
documented. So it was difficult to determine the exact causes of late preterm
delivery. And we couldn’t assess the neurodevelopment complications due to
inadequate and incomplete follow up.
preterm infants suffer from short term morbidities, complications, required
longer hospital stay and have higher mortality rate when compared to term
neonates. Late preterm infants require special care and attention since birth.
Further research should be carried out to evaluate the role and safety of
antenatal corticosteroids in improving lung maturity and decreasing the
incidence of RDS in late preterm infants.
Obstetricians should pay attention
to the risks of the late preterm neonates whether acute or long term when they
decide to deliver a preterm baby when there is no clear maternal or fetal
indications for early delivery.
1. Engle W A, Kominiarek M A. Late Preterm Infants, Early Term Infants, and Timing of
Elective Deliveries. Clin Perinatol 2008;35:325–341.
Savitha M R, Swathi S S. Morbidity
and mortality profile of late preterm neonates as compared to term neonates
from a tertiary care centre in Mysore, India. Int J Contemp
Pediatr. 2016 Feb;3(1):164-168.
3. Tsai M L, Lien R, Chiang M C, et al.
Prevalence and Morbidity of Late Preterm Infants: Current Status in a Medical
Center of Northern Taiwan.
and Neonatology 2012; 53:171-177.
4. Kugelman A, Colin A A. Late Preterm Infants: Near Term But Still in
a Critical Developmental Time period. Pediatrics October
C, Gürsoy T, Ovalı F. Short-Term Outcomes
and Mortality of Late Preterm Infants. Balkan Med J 2016;33(2):198-203.
6. Engle W A, Tomashek
K M, Wallman C. “Late-Preterm”
Infants: A Population at Risk. Pediatrics 2007;120(6);1390-1401.
7. Kumar C, Sharma D, Pandita A.
Late Preterm and Early Term Neonates: A New Group of High Risk Newborn in
Neonatology with Varied Complications. J Neonatal Biol 2014;3(5):E-112.
8. Morgan J C, Boyle E M. The late preterm infant. Paediatrics and child health.
9. Visruthan N K, Agarwal P, Sriram B,et al.
Neonatal Outcome of the Late Preterm
Infant (34 to 36 Weeks): The Singapore Story. Annals Academy of
Medicine. July 2015;44(7):235-243.
T N K. The Problem of Late-Preterm
A Workshop Summary.
Pediatric research 2006;60(6):775-776.
O. Unfavourable outcomes associated with late preterm birth:
Jordan. J Pak Med Assoc August
12. Begum L N, Ahmed F, Haq K, et al. Clinical
outcome of the late preterm infants. BSMMU J 2017;10(3):132-134.
13. Araújo B F, Zatti H, Madi J M, et al. Analysis of neonatal morbidity and
mortality in late-preterm newborn infants. J Pediatr
14. Jakiel G, Wilińska M, Bińkowska M,
Kowal A, et al. Late preterm
infants – impact of perinatal factors on neonatal results. A clinical study.
Annals of Agricultural and Environmental Medicine 2015; 22( 3):536–541.
R W, Habli M, Snyder C C, et al. Late Preterm
Birth. Reviews in obstetrics & gynecology 2010;3(1).10-19.
A, Ali S R, Ahmed S, et al. Short-Term Neonatal Outcome in Late Preterm
vs. Term Infants. Journal of the College of Physicians and Surgeons
Pakistan 2014; 24(1):34-38.
17. Shapiro-Mendoza C K, Tomashek K M,
Kotelchuck M, et al. Effect of late-preterm birth and
maternal medical conditions on newborn morbidity risk. Pediatrics Feb
18. Khowaja W H, Leghari A L, Hussain A S, et al.
Frequency and Early Complications of Late Preterm Infants: A Descriptive
Analysis from Two Secondary-care Hospitals of Karachi. Cureus, September
19. Reymundo M G, Suazo J A H, Aguilar
M J C, et al. Follow-up
recommendations for the late preterm
Infant. An Pediatr (Barc) 2019;90(5):318.e1-318.e8.
A E. Complications of the Late Preterm Infant. J Perinat Neonat Nurs
Shah P, Kaciroti N, Richards B, et al. Developmental Outcomes of Late
Preterm Infants From Infancy to Kindergarten. Pediatrics 2016;138(2).
22. Jain L. School Outcome in Late Preterm Infants: A Cause for Concern.
J Pediatr 2008;153:5-6.
M, McCormick M C, Mao W Y, et al. Late Preterm Infants and
Neurodevelopmental Outcomes at Kindergarten. Pediatrics September
24. Setyorini A, Soetjiningsih, Haksari E L. Cognitive outcome in late preterm babies. Paediatr Indones July 2010;50(4):239-244
25. Wagh A S, Jain N. Comparison of neonatal morbidities of late preterm
with term born babies. JPBMS 2012;15 (9):1-5.
E M, Johnson S, Manktelow B, et al.
Neonatal outcomes and delivery of care for infants born late preterm or
moderately preterm: a prospective population-based study. Arch Dis Child
Fetal Neonatal Ed 2015;100:F479–F485.
M J, Bhutani V K, Bogen D, et al. Hyperbilirubinemia
in the Newborn Infant 35 Weeks’ Gestation: An Update With Clariﬁcation.
Pediatrics October 2009;124(4):1193-98.
28. Ballard JL, Khoury JC, Wedig K, et al.
New Ballard Score, expanded to include extremely premature infants. J