Outcome Data for 22 to 25 week and 401 to 1000 g Birth Weight Newborns
Background Information
Significant challenges remain for decision making at the lower border of
viability. Individual patient decisions are made based on the best
available information at the time. In an effort to assist individual
decision making, data from the NICHD Neonatal Research Network are
available for the practice community and parents with respect to survival
and intact survival utilizing information from 4446 births at 22-25
weeks. The purpose of this website is to provide outcome to be used
by physicians, care providers, and parents on a case-by-case basis.
This outcome data are based on standardized assessments at 18-22 months
adjusted age (post term) in the NICHD Neonatal Research Network for
22-25 wk 401-1000 g infants born in Network centers between 1998 and
2003. (Outborn infants and infants with a major congenital anomaly
were excluded). As was shown for these infants, use of five
factors—gestational age (best obstetric estimate in completed weeks),
birth weight, sex, antenatal corticosteroids (any), and singleton
birth—allowed a better estimate than using gestational age alone.
With different combinations of these risk factors, the percent of
infants observed to have a favorable outcome was as large as 30%
greater or 30% less than that estimated using gestational age alone.
Use of these 5 risk factors allows the likelihood of different outcomes
to be estimated for individual infants assuming outcomes like those for
the Network as a whole during this period. Because prognosis may be
perceived differently depending on how it is expressed, the likelihood
of a favorable outcome (top 3 rows of estimates) as well as the likelihood
of an unfavorable outcome (bottom 3 rows) is shown. Two columns of
estimates are provided. The first column is based on findings for all
infants including those who died without receiving mechanical ventilation.
The second column is based only on infants who received intensive care
(mechanical ventilation). For risk groups in which some infants died
without receiving mechanical ventilation, the first estimate is often
lower than the second. The rate of a favorable outcome had no infants
died without receiving mechanical ventilation is likely to be intermediate
between the two estimates. Neurodevelopmental impairment (NDI) was defined
as a Bayley mental developmental index or psychomotor developmental
index <70, moderate/severe cerebral palsy, bilateral blindness, and/or
bilateral hearing loss requiring amplification. Profound impairment was
considered to be present when the lowest Bayley score was recorded as
<50 or the gross motor function level was 5 (Palisano criteria).
These estimates apply only at birth. Sonographic estimates of fetal weight
may be used in anticipating birth weight. However, it would be important
to assess the minimum and maximum likely birth weight consistent with the
potential error of sonographic estimates in your center.
In interpreting the estimates, it is important to recognize that outcomes
change over time and that outcomes differ between centers for a variety
or reasons, including patient population, obstetric care, and care after
discharge home. (Within the Network, the ratio of the observed rate of
adverse outcomes among ventilated infants in different centers relative
to that expected from the outcomes for the Network as a whole varied more
for death (0.60-1.38), than for death or profound impairment (0.75-1.23)
or death or impairment (0.85-1.17). To help in assessing the extent to
which findings in your center may differ from that for the overall
network, the tables below describe the Network population and outcomes
used in deriving these estimates.
Gestational Age Specific Outcomes for Inborn Infants 22-25 Weeks Gestational Age
Gestational Age (Completed Weeks; Best Ob Estimate) |
Death before NICU Discharge |
Outcomes at 18–22 Months Adjusted Age* |
Death |
Death or Profound Impairment |
Death or Neurodevelopmental Impairment |
22 weeks |
95% |
95% |
98% |
99% |
23 weeks |
74% |
74% |
84% |
91% |
24 weeks |
44% |
44% |
57% |
72% |
25 weeks |
24% |
25% |
38% |
54% |
* Death or profound impairment and death or neurodevelopmental impairment
determined for 4165 examined infants; death at 18-22 month determination made
using a denominator of all 4446 cohort infants.
Gestational Age Specific Outcomes for Only Mechanically Ventilated Inborn Infants
22-25 Weeks Gestational Age
Gestational Age (Completed Weeks; Best Ob Estimate) |
Death before NICU Discharge |
Outcomes at 18–22 Months Adjusted Age** |
Death |
Death or Profound Impairment |
Death or Neurodevelopmental Impairment |
22 weeks |
79% |
80% |
90% |
95% |
23 weeks |
63% |
63% |
76% |
87% |
24 weeks |
40% |
41% |
55% |
70% |
25 weeks |
23% |
24% |
37% |
54% |
**For mechanically ventilated infants, death or profound impairment and death or neurodevelopmental impairment determined for 3421 infants with known outcomes at 18-22 months; death at 18-22 month determination made using a denominator of all 3702 cohort infants.
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