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One important reason this issue has not received more attention is the
lack of good data on the numbers and trends of pregnancy-associated crashes and
related injuries to pregnant women and their babies. For the most part, such
cases are greatly under-reported or unreported in crash and vital statistics
data systems and remain off the radar screen of highway safety agencies.
The barriers to better data are many and deeply enmeshed in
the nature of the problem and the design and limitations of current vital statistics death data and
injury and crash injury reporting
systems. Like SIDS, attributing a fetal death or a particular birth defect or
fetal injury to a crash is often a diagnosis of exclusion. Further, such
diagnoses are quite often hindered by the absence of in-depth investigation of
potential clinical, crash and biodynamic factors.
In the sections below, the limitations of each potential source of reporting
of both maternal and fetal outcomes is discussed in detail.
1. Mortality (deaths) in the Vital Statistics Systems
There are several situations that may arise when a pregnant woman is fatality
injured in a car crash or other violent death.
- Most often, if the woman dies shortly after the incident,
the baby usually does not survive. There are heroic and emotional exceptions
when the pregnancy is more developed and the fetus is viable outside the
womb, but such cases
make the news because they are so rare. In the most common scenario
involving maternal death,
the death of both the mother and baby, if there is no delivery then no birth
certificate or fetal death certificate for the baby is ever filed and
the fetal death goes uncounted.
- Some states do have a place on the mother's death
certificate to mark whether the woman was pregnant, but
special studies have shown that this indicator box was not checked 65%
of the time. Furthermore, persons killed in motor vehicle crashes are
less likely to be autopsied to confirm early pregnancies than other
types of violent deaths. The result is that crash deaths to pregnant
women are poorly counted.
- If the baby is less than 20 weeks gestation there is
usually no requirement to file a fetal death certificate at all, whether
delivered or not, and the fetal death goes uncounted.
If the woman does not die (or survives long enough to result in a delivery)
there are again different situations to consider:
- If the baby is stillborn less than 20 weeks gestation,
usually no fetal death certificate is required and the fetal death goes
uncounted. Even if such cases were reportable, it may be difficult with
current diagnostic procedures and practices to assign with certainty whether
the crash caused or played a role in the death. The fetus is quite small at
this age and still-births for many other known and unknown causes are quite
common until about the fourth month of pregnancy. Like SIDS, attributing a
fetal death or birth defect to a crash is often a diagnosis of exclusion. This is an important area
for more basic research.
- If the baby is stillborn and older than or equal to 20
weeks gestation, a fetal death certificate is usually filed. However, if and when the crash is implicated, the cause of death on the
fetal death certificate is categorized as "death to maternal injury,"
usually without any specific coding for what caused the maternal injury.
Thus, state or federal fetal death report summaries
never report the number of fetal deaths due to car crashes.
- If the baby is born live and then dies from factors
related to the crash or the mother's injuries, it is not legally a fetal
death, but an infant death. However, the same problem remains with the cause
of death on the infant death certificate. The death certificate is supposed
to be categorized as "death to maternal injury," but again, usually without
any coding for what caused the maternal injury.
Thus, state or federal infant death report summaries never report neonatal
deaths due to in utero car crashes.
2. Non-fatal Fetal Injury (morbidity) in Hospital
Discharge Data Systems
- For non-fatal events, government public health agencies that track injuries
usually rely on
data from hospitals. However, similar classification and coding problems
exist that make it almost impossible to identify from hospital data alone which
infants suffered either a birth complication or a direct injury because of a car
crash. Thus, no state or federal hospitalized injury data system reports the
number of neonatal injuries due to in utero car crashes.
3. Crash Data Systems
There are several levels and types of crash and motor-vehicle related injury
data systems. All fail to include the fetus as an injured person and are not
included as cases. Only
one federal data system (and no state system) attempts to document if a female
occupant in a crash was pregnant at the time of the crash and there is evidence
that it undercounts such cases by a factor of 3 or more (see
below).
- Most states collect police reports of crashes and
document who was injured. However, no state includes information about
pregnancy status on any of their data collection forms or includes injured
fetuses as cases in their data systems. Thus, state crash
data systems, by themselves, do not report adverse fetal outcomes or the
number of pregnant women injured in car crashes.
- In the U.S.,
NHTSA investigates
all fatal crashes in a system called the
Fatality Analysis Reporting System (FARS). This system does not include
a pregnancy variable for female occupants. Thus,
NHTSA
does not report the number of pregnant women killed in car crashes.
- The
Fatality Analysis Reporting System (FARS) contains variables (since
1982) that identify the special instance of fetal death when the mother also
dies. For 2002, this system reported 42 such incidents. To-date, no analysis
or report of the cases defined by these variables (DR_CF1-4 and P_CF1-3) has
been made (to our knowledge) and no further information about the fetus is
recorded. Furthermore, its completeness has never been measured nor its
methods documented. If the fetus dies but the mother survives (the more
likely scenario) the fetal death is not usually recorded in this reporting system.
- In the US,
NHTSA investigates a
sample of police reported crashes called the
National Automotive Sampling System (NASS). Since 1995 this system has
included a pregnancy variable. A
paper was published using this data in 2002. Although the data system
contains little fetal outcome data and
evidence suggests it undercounts pregnancy associated cases by a
factor of 3 or more, these data are useful for understanding patterns of
age, restraint use, and driver status among the reported cases. Individual
cases and vehicle crash pictures involving pregnant women (without
identifiers) can be viewed
online (use the 'sex' variable to choose pregnant cases, by trimester).
Insurers
Many of the barriers to tracking pregnancy related crashes and its immediate
impact can be overcome by
instituting affordable, efficient and ongoing linkages between crash reporting
systems and birth and fetal death vital statistics data. A handful of research
projects (Wolf,
1993,
Schiff, 2002, &
Hyde 2003) have demonstrated the use and begun to explore the advantages of
this technique and
AASP
encourages this policy at the state level.
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