prenatal WIC participants must document their pregnancy
status, an act that encourages a formal prenatal care visit and
thereby increases the likelihood of being drawn at an early
stage into a prenatal care health network. Improved prenatal
care is both an important goal and an achievement of the
WIC program.
Benefits associated with WIC participation do not appear
limited to any particular population group, but are seen
across a wide spectrum of subpopulations. Subpopulations
at higher nutritional risk for poor pregnancy outcomes,
however, appear to benefit more strongly, especially teenage,
unmarried, and Hispanic origin women. In general, the
neediest populations seem to benefit the most from the WIC
program.
Increased duration of participation in the WIC program
appears to be associated with enhanced birth outcomes, in
general accord with prior WIC research.3'4 The birth outcomes
for the longest duration WIC participants reach or
surpass the State's overall mean birthweight (3343 grams)
and incidence of LBW (6.55 per cent).
Estimating the exact magnitude of the cumulative benefits
associated with increased duration of participation in
WIC is methodologically complicated. Duration of participation
and gestational age are, in part, confounded. WIC
benefits may be mediated through increased gestational age
but in turn, increased gestational age allows for increased
duration in WIC. Any grouping of subjects for statistical
analysis on the basis of extensive absolute duration of
participation in WIC virtually assures that they have longer
gestations and higher birthweight; while any statistical corrections
for length of gestation will eliminate the benefits
associated with the program's enhancement of gestational
age.
Since no ideal analytic solution exists,'3 we used two
alternative methods: absolute duration in WIC, and percentage
of pregnancy in WIC. Since the absolute duration
measure may be an over-estimation and the percentage of
pregnancy may be an under-estimation, we suggest that the
magnitude of the cumulative benefits associated with WIC
should fall between these two estimates. Both methods of
analyses imply that more extensive WIC participation is
associated with more beneficial birth outcomes. The absolute
duration analysis would indicate that the benefits are not
simply linear; WIC participation greater than six months
would appear maximally beneficial.
It is not only chance or self-motivation that determines
if a person enters WIC early or late. Barriers and incentives
to early participation exist. Haddad and Willis'4 have shown
that the probability of women entering WIC in their first
three months of pregnancy is significantly enhanced if the
WIC program site has been open a long time, delivers it
supplementation through retail stores, and uses public service
announcements. The potential benefits associated with
the WIC program are not yet being reached; only 22 per cent
of the WIC prenatal participants participated for more than
six months.
The comprehensiveness of the case population is an
important element in assessing the validity and generalizability
of the present study. The names of 525 women administratively
excluded from the WIC prenatal program were
omitted from this study. Unfortunately, very little demographic
or motivational information is available about them
from the WIC computerized records. The 353 names, which
had no reason specified for their exclusion, were similar
racially to the WIC study population (68.6 per cent White