Maternal Smoking & the
1998 Master Settlement
Agreement
Douglas E. Levy, Ph.D.
Ellen R. Meara, Ph.D.
Dept. Health Care Policy, Harvard Medical School
Support Provided by AHRQ T32-HS00055 & NIA T32-AG00186
Price Responsiveness of Smoking

Elasticity of smoking participation


General population  -0.25
Pregnant women





-0.5 (Evans & Ringel; Natality Files 1989-1992)
-0.7 (Ringel & Evans; Natality Files 1989-1995)
-1.0 (Colman et al.; PRAMS data 1993-1999)
The Master Settlement Agreement led to an immediate
22% (45¢) increase in cigarette prices
Price increase from MSA could reduce

Smoking among pregnant women 10-20%
Low birth weight 2-4%

DID IT?

Study Design

Examined four outcomes
Maternal smoking participation and intensity
(# of cigarettes/day)
 LBW and birth weight in grams



Used interrupted time-series regressions to
determine whether there were important
changes in outcomes following the MSA
Subgroup analyses by mothers’ age, race,
education
Study Data


National Vital Statistics Natality Detail Files from 1996 to 2000
We exclude




States not reporting maternal smoking (CA, IN, SD, upstate NY)
Non-singleton birth
Mother <15 or >44 years old
Incomplete data on outcomes and demographics


Control variables:


4% had missing data given first three criteria
calendar month, state, excise taxes, maternal demographics, pregnancy
characteristics, prenatal care, heavy alcohol consumption
N = 9,638,863
Study Period

Infants conceived from January 1996 to
February 2000


Adequately capture pre- and post-MSA trends
without picking up later non-price effects of MSA
Exclude infants conceived from March 1998
through November 1998

Avoid pregnancies only partially affected by MSA
Summary Statistics
Outcome
All
Smokers
NonSmokers
Smoking
12.1%
100%
0%
1.3 (4.4)
11.0 (7.4)
0 (0)
5.9%
10.1%
5.3%
#Cigs/day (sd)
LBW
Birth weight, g (sd) 3352 (572) 3161 (575) 3378 (567)
Maternal Smokers Are…




More likely to be white
Less likely to have
attended college
Younger
Less likely to be married



Likely to have fewer and
later prenatal care visits
More likely to have had a
prior preterm birth
More likely to drink
heavily during pregnancy
Regression Analyses





Yits = 0 + timet + MSAt + timet*MSAt + Montht +
Demographicsi + us + eist
Time is monthly count; captures secular trend
MSA captures immediate changes beginning Nov. 1998
Time*MSA captures changes in trend following MSA
Month captures seasonal variation in outcome
Predicted Smoking Prevalence
MSA, Nov. 1998
15%
10%
Absent
the MSA
5%
With the
MSA
0%
n
Ja
-00
9
l-9
Ju
8
c-9
De
8
n-9
Ju
7
v-9
No
7
y-9
Ma
6
t-9
Oc
6
r-9
Ma
Predicted Smoking
Prevalence 15mos Post-MSA
11.4%
Rel.
%
-2.2%
Pr(MSA=
MSA*time = 0)
p<0.0197
3.2
3.0
-6.3
p=0.1064
17.8
16.3
-8.2
p<0.0001
Population
w/o
MSA
w/MSA
All
11.7%
Hispanic
15-19yo
Predicted LBW
Prevalence 15mos Post-MSA
6.2%
Rel.
%
-1.8%
Pr(MSA=
MSA*time = 0)
p=0.0402
5.7
5.5
-4.8
p=0.3726
9.0
8.7
-3.5
p=0.1077
Population
w/o
MSA
w/MSA
All
6.3%
Hispanic
15-19yo
Why So Little Effect?


Perhaps remaining smokers are less likely to
change habits in response to price hikes
Perhaps earlier estimates based on changes in
state excise taxes were confounded
Simultaneous changes in attitude towards smoking
 Simultaneous tobacco control legislation

Limitations




No control group
Assumes trend is linear
Maternal smoking is self-reported
Major states were excluded from the analysis

20% of births during this period
Implications

Pros of price increases for tobacco control



Cons of price increases for tobacco control



Young women and their infants may benefit
Price changes affect most smokers
Less effective than commonly believed
Regressive taxation
Next steps


Results in other populations?
Relate to new evidence re: long-run price-responsiveness