Maternal Smoking

1
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

2
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?

3
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

4
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 lt15 or gt44 years old
• Incomplete data on outcomes and demographics
• 4 had missing data given first three criteria
• Control variables
• calendar month, state, excise taxes, maternal
  demographics, pregnancy characteristics, prenatal
  care, heavy alcohol consumption
• N 9,638,863

5
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

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Summary Statistics
7
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

8
Regression Analyses

• Yits ?0 ?timet ?MSAt ?timetMSAt
  ?Montht ?Demographicsi us eist
• Time is monthly count captures secular trend
• MSA captures immediate changes beginning Nov.
  1998
• TimeMSA captures changes in trend following MSA
• Month captures seasonal variation in outcome

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Predicted Smoking Prevalence
MSA, Nov. 1998
10
Predicted Smoking Prevalence 15mos Post-MSA
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Predicted LBW Prevalence 15mos Post-MSA
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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

13
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

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Implications

• Pros of price increases for tobacco control
• Young women and their infants may benefit
• Price changes affect most smokers
• Cons of price increases for tobacco control
• Less effective than commonly believed
• Regressive taxation
• Next steps
• Results in other populations?
• Relate to new evidence re long-run
  price-responsiveness

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Predicted Smoking Prevalence 15mos Post-MSA
16
Predicted Cigarettes/Day15mos Post-MSA
17
Predicted Cigarettes/Day15mos Post-MSA
18
Predicted LBW Prevalence 15mos Post-MSA
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Predicted LBW Prevalence 15mos Post-MSA
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Predicted Birth Weight 15mos Post-MSA
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Predicted Birth Weight 15mos Post-MSA
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Cigarette Prices and Taxes