DISENTANGLING MATERNAL DECISIONS CONCERNING Breastfeeding and paid EMPLOYMENT

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DISENTANGLING MATERNAL DECISIONS
CONCERNINGBreastfeeding and paid EMPLOYMENT

• Bidisha Mandal, Washington State University
• Brian E. Roe, Ohio State University
• Sara B. Fein, Food Drug Administration

ASHEcon
June 23, 2010
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Motivation

• Importance of breastfeeding in developed
  countries is increasingly emphasized
• National U.S. health objectives call for
  exclusive breastfeeding for at least 6 months and
  breastfeeding duration for at least 12 months
• More U.S. mothers of infants are participating in
  the workforce
• More mothers of infants are combining market work
  and breastfeeding
• Postpartum return to work is associated with
  lower rates of initiation and shorter duration of
  breastfeeding in the U.S.
• Conflict between economic incentives from labor
  market and health benefits (to both mother and
  child) from breastfeeding

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Objective

• What is the decision process regarding work leave
  and breastfeeding durations?
• What is the decision process regarding work
  effort and breastfeeding intensity?

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Data Infant Feeding Practices Study II

• Conducted by the FDA in collaboration with the
  CDC from May 2005 to June 2007
• Longitudinal study of women from late pregnancy
  through their infants first year of life - 12
  surveys (primarily mail)
• 1 prenatal questionnaire
• 1 telephone interview near the time of the
  infants birth
• 1 neonatal questionnaire at infant age 1 month
• 9 questionnaires sent about every 4 weeks during
  infant ages 2 to 7 months and then approximately
  every 7 weeks until infant age 12 months
• 4902 qualified pregnant women completed the
  prenatal questionnaire

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Sample

• Not enough information if due date was more than
  3 months away or did not complete neonatal
  questionnaire
• 1885 cases deleted (3017 remaining)
• Conditioning on pre-birth market work
• 1506 cases deleted (1511 remaining) if no
  prenatal work activity
• Prenatal work working for pay at any time from
  the 3 months before pregnancy until last
  trimester does not have to be full-time worker
• 468 women did not initiate breastfeeding and/or
  worked pre-birth but did not intend to return to
  work
• Excluded
• 1049 remaining
• Have full information (on all variables of
  interest) for only
• N 744 women for duration models
• N 648 women for month 3 intensity model
• N 586 women for month 6 intensity model

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Selection Bias?
Initiation
Breastfeeding duration
Intention
Work leave duration

• Breastfeeding initiation and work leave duration
• Work leave duration is shorter for those who do
  not initiate (11.3 wks vs. 13.5 wks)
• But, using Hausman endogeneity test, initiation
  is not endogenous to the determination of work
  leave duration
• Intention to return to work and breastfeeding
  duration
• Breastfeeding duration is shorter for those who
  return to work (25.3 wks vs. 31.4 wks)
• Again, using Hausman endogeneity test, intention
  is not endogenous to the determination of
  breastfeeding duration

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Models

• Breastfeeding and work leave durations
• Both activities are right censored
• End of survey censoring or missing data censoring
• Exclusive breastfeeding and work leave durations
• Both activities are right censored
• End of survey censoring or missing data censoring
• Breastfeeding intensity and work effort at months
  3 and 6
• Both activities are left censored
• Observe intensity or effort only if participating
  in activity
• 4 cases both observed, only one observed, both
  unobserved

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Variables of Interest

• Dependent variables
• Length of time that a woman breastfeeds her
  infant (25.3 wks)
• Length of time that a woman exclusively
  breastfeeds her infant (7.8 wks)
• Length of time before a woman returns to
  employment postpartum (13.5 wks)
• Number of breastfeedings per day at infant age 3
  months (4.7)
• Number of breastfeedings per day at infant age 6
  months (3.2)
• Number of hours of market work per week at infant
  age 3 months (10-19 hrs/wk)
• Number of hours of market work per week at infant
  age 6 months (20-29 hrs/wk)
• Independent variables
• Background age, education, race, marital
  status, residence
• Parity number of other children and experience
  with breastfeeding
• Birth and breastfeeding if mother was
  breastfed, comfort, pregnancy complications,
  problem breastfeeding, attended breastfeeding
  class
• Prenatal job characteristics self-employed,
  part-time work, available work leave, supportive
  at work, satisfaction with work, contribution to
  family income, occupation type

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Estimation Method

• Full Information MLE
• Log scale

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Data Limitations

• Sample is probably not reflective of the average
  characteristics of the U.S. population
• Higher average education
• Higher income
• Return to same employer
• Not known

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Work Leave and Breastfeeding Durations

• Decision process is recursive rather than fully
  simultaneous
• Longer leave from work increases duration of
  breastfeeding
• Every percent increase in work leave increases
  breastfeeding duration by half percent
• Duration of breastfeeding is not a significant
  determinant of work leave
• Significant covariates
• Mothers age, education and married status are
  positively related to duration of breastfeeding
• Women in western and northeastern states of U.S.
  breastfeed longer
• Women with one other child who was also breastfed
  breastfeed longer
• Women with no work leave available return to work
  sooner
• Women who are satisfied with their work return
  sooner
• Women who have 1 or more children and who has not
  breastfed before take longer leaves women who
  have more than 1 child and has breastfed before
  take shorter leave

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Exclusive Breastfeeding Duration

• Decision process is again recursive rather than
  fully simultaneous
• Every percent increase in work leave increases
  exclusive breastfeeding duration by 0.66 percent
• Duration of exclusive breastfeeding is not a
  significant determinant of work leave
• Additional significant covariates
• Self-employed women exclusively breastfeed longer
• Self-employed women take longer leave from work
• Women whose contributions to household income is
  more than 50 exclusively breastfeed for shorter
  duration
• Change in sign
• Women with one other child who was also breastfed
  exclusively breastfeed for shorter duration (time
  constraints?)
• Negative correlation between unobserved factors

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Work Effort and Breastfeeding Intensity

• Recursive process (both months 3 and 6)
• Work effort constraints breastfeeding intensity
  but the reverse is not true
• Every 5-10 hour/week increase in work is
  associated with 1 less breast-milk feeding per
  day
• Common significant covariates in months 3 and 6
• Higher number of daily breastfeedings among
  higher educated women
• Lower number of daily breastfeedings among women
  in southern states
• Lower number of daily breastfeedings among women
  who are not comfortable with breastfeeding
• No available leave is associated with less work
  effort
• Higher contribution to family income is
  associated with higher work effort

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Conclusions

• Healthy People 2010
• Goal 50 women breastfeeding at month 6, 25 at
  1 year
• 1990s 29 women breastfeeding at month 6, 16
  at 1 year
• Current 43 women breastfeeding at month 6, 21
  at 1 year
• High degree of competition between breastfeeding
  and work
• In terms of both duration and effort
• Results indicate that employment decisions are
  made first
• Longer work leave implies longer duration of
  breastfeeding and exclusive breastfeeding
• More time spent at work means lesser number of
  breastfeedings
• Working women probably face constraints at the
  workplace that are more rigid than those
  surrounding breastfeeding decisions
• Similar results found in IFPS I (1992-1993)
• Need for more workplace support