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Most
of the risks to infants resulting from multiple gestation
pregnancies are due to the increased likelihood of premature
delivery. The more babies who result from a pregnancy,
the greater the likelihood of premature delivery. The
average length of pregnancy is as follows:
Single baby: 40 weeks
Twins: 36 weeks
Triplets: 32
weeks
Quadruplets: 28
weeks
Each
additional baby in the uterus shortens the pregnancy by
about 4 weeks on average. The survival and outcomes of
premature infants are improving year by year as a result of
new developments in high-risk obstetrics and newborn
intensive care. However, significant risks remain,
particularly for infants born very early in pregnancy
(before 30 weeks).
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Quadruplets
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If quadruplets are born before 24 weeks, it is likely that
all will die. Even at 24 weeks, there is only about a
13% chance that all four infants will live. At 28
weeks, the chance for each infant is about 95%; so
statistically, the chance of that all four will live is
about 81% (.95 x .95 x .95 x .95).
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Triplets
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If triplets are born at the average time in pregnancy, 32
weeks, the survival chance for each infant is about 98%.
The chance that all three will live is about 94% (.98 x .98
x .98). In real life, due to other problems separate
from prematurity, the survival risk is likely to be much
lower.
These
complex probabilities can be summarized in a table as shown
below.
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Single
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Twins
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Triplets
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Quads
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24
weeks
|
|
|
|
|
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Survival
of each baby
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60%
|
60%
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60%
|
60%
|
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Survival
of all babies
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60%
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36%
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22%
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13%
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28
weeks
|
|
|
|
|
|
Survival
of each baby
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95%
|
95%
|
95%
|
95%
|
|
Survival
of all babies
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95%
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90%
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86%
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81%
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32
weeks
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|
|
|
|
|
Survival
of each baby
|
98%
|
98%
|
98%
|
98%
|
|
Survival
of all babies
|
98%
|
96%
|
94%
|
92%
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36
weeks
|
|
|
|
|
|
Survival
of each baby
|
99%
|
99%
|
99%
|
|
|
Survival
of all babies
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99%
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98%
|
97%
|
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Numbers in
bold indicate the most likely outcome for each column
(# of
babies).
As
the number of babies in a pregnancy increases, the length of
pregnancy needed for survival of all babies increases, but
the expected pregnancy length decreases.
|
Single
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Twins
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Triplets
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Quads
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Weeks
of pregnancy needed to reach 90% survival of all
babies
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27
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28
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30
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32
|
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Average
length of pregnancy
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40
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36
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32
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Length
of Hospital Stay
The total
hospital costs for the care of the babies depends on two
factors: the number of babies and the length of
hospitalization. The average hospital stay is about 3
months for babies born at 24 weeks and 2 months at 28 weeks,
1 month at 32 weeks and 1 week at 36 weeks. Thus the
expected total number of hospital days for all babies would
be as follows:
Single baby:
2 days x 1 = 2
Twins:
7 days x 2 =
14
Triplets:
30 days x 3 = 90
Quadruplets:
90 days x 4 = 360
These
estimates depend on the assumption that a pregnancy will be
of average length. It is often possible, with careful
obstetrical management for the pregnancy to be prolonged
past the average length. Excellent health care
insurance is obviously important for families with
multiple-gestation pregnancies. It is important to be
certain that your insurance will cover neonatal intensive
care in a Level 3 or Comprehensive Center, such as the
University of North Carolina.
Multiple
gestations often require extended periods of bed rest for
the mother at home or in the hospital. Exact figures
are not available for these periods of time.
Complications
Another
important consideration is the risk of complications of
prematurity. The risk increases with shorter
pregnancies. The most important complications of
prematurity are summarized.
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Lung
problems
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The most common problem confronting premature infants is
immaturity of their lungs. This problem often requires
special treatment and may occasionally cause long-term
problems in survivors; it may also delay the recovery of
some premature babies, especially those born before 28 weeks.
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Bleeding
complications
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One of the most serious potential complications of
prematurity is spontaneous bleeding in the brain. This
occurs in 10 to 20% of babies born before 32 weeks. A
chance of hemorrhage of any severity in infants <32 weeks
is 20%, and the chance of severe brain hemorrhage is 11%.
The risk is higher in the earliest babies. Many of
these hemorrhages are small and cause no long-term effects,
but more severe bleeding episodes may be associated with
permanent impairment of brain function. Bleeding in
the lungs is another serious potential complication in very
early premature babies.
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Gastrointestinal
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Necrotizing enterocolitis is a complication of prematurity
resulting in nonviable portions of the intestines.
This may result in sepsis of the infant, often requiring
bowel segmental resection.
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Eye
problems
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Infants born very prematurely (before 28 weeks) may have
abnormal growth of blood vessels on the retina, the back of
the eye. This is a common complication that usually
goes away spontaneously. In severe cases, the problem,
if untreated, may progress to retinal detachment and
blindness. Premature infants are also at increased
risk of other eye problems such as nearsightedness and eye
muscle problems. It is quite common for premature
infants to require glasses later in childhood because of one
or more of these problems.
This
information is provided to assist you in evaluating the
risks to infants resulting from multiple gestation
pregnancies. The figures presented here are inexact
and likely to change with time and improving obstetrical and
pediatric therapy. If you would like to discuss any of
these issues further, please ask your physician or nurse to
arrange for a neonatology consultation with your hospital.
Figures for survival are slightly higher in the USA.
Resource:
UNC
Department of Obstetrics & Gynecology
 
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