pregnantmother77: Objectives:
Motor vehicle crashes are the leading cause of hospitalized trauma
during pregnancy. Maternal injury puts the fetus at great
risk, yet little is known about the
incidence, risks, and characteristics of pregnant women in crashes.
Setting and methods:
Police reported crashes were analyzed from the National Automotive
Sampling System Crashworthiness Data System. Since 1995,
this system recorded
pregnancy/trimester status. Pregnant and non-pregnant women 15–39 years
of age were compared by age,
driver status, seat belt use, and
treatment. Belt use and seating position were examined by trimester.
Results: There were 427 pregnant occupants identified (weighted n=32 810, 2.6%, SE 12 585, rate 13/1000 person years). The mean age
was 24.9 compared with 24.8 years (pregnant v
non-pregnant). Cases were distributed by trimester as follows: first
29.8%, second 36.4%, and third 33.8%. Pregnant women
were drivers 70% of the time compared
with 71% for non-pregnant women. No belt use was 14% compared with 13%
(pregnant v non-pregnant). Mean injury severity was lower for
pregnant women but they were more likely to transported or hospitalized.
Improper belt use decreased after the
first trimester and there was little change in driver proportion by
trimester. Third
trimester hospitalization rates
increased.
Conclusions:
Pregnant occupants in crashes have similar profiles of restraint use,
driver status, and seat position but different treatment
indicators compared to non-pregnant
occupants. Trimester status has relatively little impact on crash risk,
seating position
or restraint use. Undercounting of
pregnant cases was possible, even so, 1% of all births were reported to
be involved in
utero in crashes. Little research has
focused on developmental outcomes to infants and children previously
involved in exposure
to these crashes.
Motor vehicle crashes are the leading cause of traumatic fetal injury mortality,1 and the leading cause of death2,3 and serious trauma4
during pregnancy. Maternal injury may put the fetus at great risk, yet
little is known from population based studies about
the characteristics and risks of pregnant
women involved in motor vehicle crashes. Such information is necessary
to begin
to understand the magnitude of fetal motor
vehicle trauma exposure, which women are at highest risk, what role
occupant behaviors
play, and to put the problem into the
proper perspective with other crash, environmental exposure, and
reproductive and child
health issues.
PARTICIPANTS AND METHODS
Data were analyzed from the
1995–99 National Automotive Sampling System Crashworthiness Data System
(NASS/CDS). NASS/CDS crashes
are a probability sample of police
reported US traffic way crashes that involve property damage and/or
personal injury.5
Weighted estimates are representative of the US population. Since 1995,
this system has recorded pregnancy and trimester
status derived from interviews and
medical record reviews. Pregnant and non-pregnant women 15–39 years of
age were compared
by age, driver status, seat belt use,
and treatment level. Driver status, restraint use, and crash risk were
examined by trimester.
After removing one pregnancy associated
case and 13 non-pregnancy associated records with large weights (those
with weights
>20 000), there were 427 unweighted
pregnancy related and 11 972 non-pregnancy cases identified from which
annualized weighted
estimates were derived. Standard errors
were computed for point estimates derived from the entire sample using
SUDAAN software
(Research Triangle Institute, North
Carolina).
Incidence rates were
calculated per 1000 person years. For the pregnant population, the
persons at risk (denominators) were
derived from age specific US birth data
and adjusted downward to account for the nine month period of gestation
and the assumption
that most pregnancies would not be
detectable in the first month of pregnancy. For example, if there were
100 000 live births
per year, multiplying 100 000 by 8/12
represents the actual person years of exposure—that is, the person years
among which
women could realistically have had
their pregnancies identified. Lowering the denominator has the net
effect of adjusting
the estimated rates for pregnant women
upwards. For the non-pregnant rates, person years and annual population
rates are equivalent.
RESULTS
There were an estimated
(weighted) 32 810 (SE 12 585) pregnant occupants annually involved in
crashes or 2.6% of all women
in crashes from the ages of 15–39. This
translates to a crash rate among pregnant women of 13/1000 person years
(1.3%). For
comparison, there were 1 251 269 (SE
127 522) women ages 15–39 not reported pregnant (rate 26/1000 person
years) and 23 188
(SE 3700) infants (rate 6.1/1000 person
years) reported in crashes. The mean age for pregnant women was 24.9
versus 24.8 for
non-pregnant women. Among pregnant
women, the highest crash rate per 1000 live births was in the youngest
age group. In peak
childbearing years (ages 20–29), at
least 3% of all women involved in a police reported crash were pregnant.
Pregnant women were more
likely than non-pregnant women to be transported to the emergency
department and released or hospitalized.
Airbag deployment did not differ much
between pregnant and non-pregnant cases; airbags were deployed among 15%
of the pregnant
cases and 13% of the non-pregnant
cases. Other selected comparisons between the pregnant and not reported
as pregnant cases
are detailed in tables 1 and 2.
