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Triplet Morbidity and Mortality in a Large Case Series
Sybil Barr, MRCP
Sarah Poggi, MD
Martin Keszler, MD
OBJECTIVE:
A significant increase in the triplet birth rate has occurred recently. This rise
is of concern, as these infants are historically reported to be at risk of
adverse outcome. Thus, we examined the outcome of triplet births in a large
contemporary case series.
STUDY DESIGN:
Since 1993, detailed clinical data have been collected on all patients
admitted to our Neonatal Intensive Care Unit. We retrospectively analyzed
this database to examine triplet outcome.
RESULTS:
A total of 51 consecutive sets of triplets were born over a 9-year period.
The mean birth weight for triplets was 1789±505 g, mean gestational age
was 32.6±2.7 weeks, with discordancy present in 17.6% of neonates.
Complications of prematurity were infrequent. Triplet survival to
discharge was 96%.
CONCLUSIONS:
This large contemporary case series of triplets demonstrates excellent
survival with low associated morbidity. These data suggest that there may
no longer be medical justification for offering selective fetal reduction to
parents with triplet pregnancies.
Journal of Perinatology (2003) 23, 368–371. doi:10.1038/sj.jp.7210950
INTRODUCTION
Over the last 20 years, there has been a 400% rise in the rate of
higher-order multiple births. Over the same time period, the
Department of Pediatrics (S.B., M.K.), Georgetown University Children’s Medical Center,
Washington, DC, USA; and Department of Obstetrics (S.P.) Georgetown University Children’s
Medical Center, Washington, DC, USA.
This case series of 51 consecutive sets of triplets demonstrates low morbidity rates and excellent
survival rates with contemporary neonatal care.
Address correspondence and reprint requests to Sybil Barr, MB BCh, MRCP, MSc, Georgetown
University Children’s Medical Center, Division of Neonatal-Perinatal Medicine #M3400, 3800
Reservoir Road, Washington, DC 20007, USA
singleton birth rate rose by only 6%, and the twin birth rate by
52%.1 According to the most recent national vital statistics, triplet
births comprise the overwhelming majority of higher-order
multiples, accounting for 91% of all higher-order multiple births.2
The increase in the triplet birth rate has been most marked in
women aged 40 years and over, with an increase of over 1000%.
Conversely, in women aged 30 to 40 years the multiple birth rate
increased by 30%, and increased by only 13% in women less than
20 years. There are two main reasons for this exponential rise in
the multiple birth rate. Firstly, the recent trend for childbearing at
an older ageFwhich in itself is associated with increased risk of
multiple birthsFaccounts for an estimated one-third of the rise in
multiple birth rates. However, the majority of the increase in
multiple births is attributable to the increasing availability and use
of fertility-enhancing medications and procedures (assisted
reproduction).
The rise in triplet births is of concern, as these infants are
historically reported to be at risk of adverse outcomes.3–5 The
mean gestational age for triplets is reported to be 32 weeks and for
twins 35 weeks, resulting in 91.6% of triplets and 47% of twins
being born preterm (<37 weeks) compared to only 9.8% of
singletons.6,7 In keeping with shorter gestations, many triplets are
born low birth weight. Overall, 92% of triplets are born with low
birth weight (<2500 g) compared to 53% of twins and only 6% of
singletons. The shorter gestational age and lower birth weights,
typically seen in triplets, both contribute to a reported 11-fold
increase in infant mortality rate when compared with singletons
and 2.2 when compared with twins.7
Selective fetal reduction is a procedure that has been widely
employed over the last 15-years to reduce the risk of complications
related to multiple gestation, and correspondingly improve
pregnancy outcome.8 Many investigators have compared the
outcome of triplets with reduced and nonreduced twins with
conflicting results. Studies in the early 1990s suggested that
reduction of triplet pregnancies improved outcome. However,
more recent studies have failed to demonstrate adverse outcome in
triplet births when compared with reduced and even nonreduced
twins.9–11 We propose that recent advances in both neonatal and
obstetric care have greatly improved outcome for younger and
lighter neonates, and thus the perceived benefits of performing fetal
reduction in order to improve neonatal outcome may no longer
exist.
We describe an up-to-date case series of 51 consecutive
sets of triplets, and report survival rates comparable to that
of twins.
Journal of Perinatology 2003; 23:368–371
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A Case Series of Triplet Outcome
Barr et al.
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25
20
Percent
METHODS
Data Acquisition
We retrospectively reviewed data from the obstetric and neonatal
patient databases at Georgetown University Hospital (GUH).
Baseline demographics and in-hospital complications were
confirmed by independent hospital chart review, and data entered
into the database by experienced medical secretaries. The records of
all triplets born between July 1993 and May 2002 were analyzed.
All infants were inborn at GUH and, because of their perceived
high-risk status all were admitted to the neonatal intensive
care nursery. GUH is a regional perinatal referral center for
high-risk pregnancies, with 1800 mostly high-risk deliveries
a year and 525 infants admitted to the neonatal intensive
care nursery per year.
Data extracted from the database included birth weight,
gestational age and Apgar scores. The percentage of infants
who were discordant in weight (defined as >20% difference)
was calculated. Neonatal outcomes recorded were as follows:
(1) chronic lung disease defined as oxygen or ventilator
dependency at 28 days of age; (2) necrotizing enterocolitis
stage II or greater, as defined by the Bell classification;12 (3) grade
III and IV intraventricular hemorrhage documented by cranial
ultrasound performed within the first week of life;13 (4)
periventricular leukomalacia detected by cranial ultrasound
performed at 4 to 6 weeks of life, as diagnosed by a pediatric
radiologist;14 and (5) retinopathy of prematurity greater than
stage I diagnosed by a pediatric ophthalmologist performing
routine eye examinations according to the American Academy
of Pediatrics guidelines.15 Length of stay in days for survivors
and survival to hospital discharge were also recorded.
Descriptive statistics were used to characterize the population
and outcomes.
15
10
5
0
23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
Weeks
Figure 1. Bar graph illustrating gestational age of triplet cohort by 1week categories.
triplets were born between 34 and 36 weeks of gestation.
Gestational age by 1-week categories is displayed in Figure 1.
Apgar scores were 7 (1 to 9) and 9 (1 to 9) at 1 and
5 minutes, respectively. Discordancy was present in 17.6% of
triplets. Three of the triplet infants had congenital
abnormalitiesFtwo with hypospadias, and one with
a ventricular septal defect.
Complications of prematurity in triplets were seen infrequently.
Chronic lung disease was diagnosed in 3% of cases, necrotizing
enterocolitis in 3%, and there were no cases of intraventricular
hemorrhage and periventricular leukomalacia, or advanced
retinopathy of prematurity. The mean length of hospital stay was
23 days, with a median of 19 days. Triplet survival to hospital
discharge was 96%.
DISCUSSION
RESULTS
Between July 1993 and May 2002, 51 sets of triplets
(153 infants) were born at GUH. Complete data were available
for all births. Data are presented as mean ±SD or median
(range) in Table 1.
The mean birth weight for triplets was 1789 ±505 g, and the
mean gestational age was 32.6±2.7 weeks. In all, 37.3% of the
Table 1 Baseline Characteristics of Triplet Cohort
Triplets
Birth weight (g)±SD
Gestational age (weeks)
Apgar 1 (range)
Apgar 5 (range)
% Discordance
Length of stay in days (range)
Journal of Perinatology 2003; 23:368–371
1789±505
32.6±2.7
7 (1 to 9)
9 (1 to 9)
17.6
23 (4 to 109) Median 19
According to the recently published National Vital Statistics
for triplets, the national average gestational age for triplets
is 32. 2 weeks, with 34.6% of births occurring between
34 and 36 weeks gestation.7 The national average birth weight
for triplets is 1698 g. The present study demonstrated
comparable results.
Previous studies suggest that higher-order multiples are more
likely to have discordant birth weights than twins and
singletons.9,16 These earlier studies reported discordancy rates of 48
and 54% for triplets, compared to 13 and 15% for twins.
Discordancy rates were 17% in the current series, a rate similar to
those seen in twins in previous studies. Improved obstetric
management of triplet pregnancies may be one factor
contributing to the observed decrease in discordancy.
Congenital abnormalities occurred in 1.9% of triplets in this
seriesFtwo neonates had hypospadias and one had
a ventricular septal defect. This rate compares favorably with a
4.8% rate of major abnormalities reported in 1998 and adds further
369
Barr et al.
weight to the supposition that triplets are not at risk of adverse
outcomes.17
This series demonstrates very low rates of morbidity associated
with triplet birth. There were no reports of intraventricular
hemorrhage or retinopathy of prematurity, and rates of only 3% for
chronic lung disease and necrotizing enterocolitis. Previous work
has reported similar frequencies of bronchopulmonary dysplasia,
necrotizing enterocolitis, intraventricular hemorrhage and
periventricular leukomalacia between twins and triplets, but
suggested that triplets had a statistically significant increased risk
of retinopathy of prematurity.17 Increased clinical surveillance and
heightened awareness may have contributed to the lack of an
excess of retinopathy in this current series. Length of hospital stay
is reported to be longer for triplets, with one paper describing a
mean stay of 51 days for triplets born at 31 weeks.18 The current
study shows a much shorter hospital stay of 23 days, albeit in a
cohort that was 1-week more mature. Such a profound difference is
surprising and potential explanations include varying institutional
discharge policy, variation in discharge policy over time, as well as
improvements in neonatal care.
In the current series, 96% of triplets survived to discharge. Over
the last 20 years, survival in higher-order multiple birth has
gradually improved. For example, survival rates in the late 1980s
were reported to be 79.0%,3 and the most recent National Statistics
including births up to 1994 report 90.6% of triplets surviving.6 This
improvement is also confirmed in other cohort studies quoting
survival rates of 94 to 97%.18–20
During the early 1990s, studies suggested a benefit in neonatal
outcome and survival if triplet pregnancies were reduced to twins.
For example, one series demonstrated that neonatal survival
improved from 79 to 97% if triplet pregnancies were reduced to
twins.3 However, this perceived benefit in neonatal survival has not
been maintained in studies published more recently. In a study
reported in 2000, there was no difference in neonatal survival when
81 sets of triplets were compared with 46 sets of triplets reduced to
twins.19 In addition, a 1999 study comparing 25 sets of triplets with
19 sets of reduced twins reported no difference in overall neonatal
survival.9
Consistent with more recent data, our triplet survival is
comparable to a large cohort (n ¼ 319 sets) of nonreduced twins
born over the same period at our institution. Twin survival was
94%, which was not statistically different from that of the triplets.
Additionally, triplet morbidity was comparable to that seen in our
twin cohort. However, there may have been selection bias in our
twin cohort as our institution is a regional referral center, and as
such these twins may be higher risk. Therefore, a more definitive
comparison would be between outcome in triplets and twins
reduced within our institution. However, as our institution is a
Catholic hospital, fetal reduction is not practiced, and thus this
comparison cannot be made. Nevertheless, our findings are
consistent with the most recently published literature, comparing
outcome in triplet and twin cohorts.
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A Case Series of Triplet Outcome
CONCLUSION
This large contemporary case series of triplet pregnancies
demonstrates excellent survival rates with very low associated
morbidity. Given our data and several other reports of such
improvements, the need to offer selective fetal reduction to parents
expecting triplets should be re-examined.
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