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Born on the first of July: An (un)natural experiment in birth timing


  • Gans, Joshua S.
  • Leigh, Andrew


It is well understood that government policies can distort behavior. But what is less often recognized is that the anticipated introduction of a policy can introduce its own distortions. We study one such "introduction effect," using evidence from a unique policy change in Australia. In 2004, the Australian government announced that children born on or after July 1, 2004 would receive a $3000 "Baby Bonus." Although the policy was only announced seven weeks before its introduction, parents appear to have behaved strategically in order to receive the benefit, with the number of births dipping sharply before the policy commenced. On July 1, 2004, more Australian children were born than on any other single date in the past thirty years. We estimate that over 1000 births were "moved" so as to ensure that their parents were eligible for the Baby Bonus, with about one quarter being moved by more than one week. Most of the effect was due to changes in the timing of induction and cesarean section procedures. We find evidence to suggest that babies who were shifted into the eligibility period were more likely to be of high birth weight. Two years later, on July 1, 2006, the Baby Bonus was increased, and we find that this again caused births to be moved from June to July. These birth timing events represent an opportunity for health researchers to study the impact of planned birthdays and hospital management issues.

Suggested Citation

  • Gans, Joshua S. & Leigh, Andrew, 2009. "Born on the first of July: An (un)natural experiment in birth timing," Journal of Public Economics, Elsevier, vol. 93(1-2), pages 246-263, February.
  • Handle: RePEc:eee:pubeco:v:93:y:2009:i:1-2:p:246-263

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    References listed on IDEAS

    1. Gans Joshua S & Leigh Andrew, 2006. "Did the Death of Australian Inheritance Taxes Affect Deaths?," The B.E. Journal of Economic Analysis & Policy, De Gruyter, vol. 6(1), pages 1-9, November.
    2. Lo, Joan C., 2003. "Patients' attitudes vs. physicians' determination: implications for cesarean sections," Social Science & Medicine, Elsevier, vol. 57(1), pages 91-96, July.
    3. Kevin Milligan, 2005. "Subsidizing the Stork: New Evidence on Tax Incentives and Fertility," The Review of Economics and Statistics, MIT Press, vol. 87(3), pages 539-555, August.
    4. Eliason, Marcus & Ohlsson, Henry, 2008. "Living to save taxes," Economics Letters, Elsevier, vol. 100(3), pages 340-343, September.
    5. Joshua S. Gans & Andrew Leigh, 2012. "Bargaining Over Labour: Do Patients Have Any Power?," The Economic Record, The Economic Society of Australia, vol. 88(281), pages 182-194, June.
    6. Wojciech Kopczuk & Joel Slemrod, 2003. "Dying to Save Taxes: Evidence from Estate-Tax Returns on the Death Elasticity," The Review of Economics and Statistics, MIT Press, vol. 85(2), pages 256-265, May.
    7. Gans, Joshua S. & Leigh, Andrew & Varganova, Elena, 2007. "Minding the shop: The case of obstetrics conferences," Social Science & Medicine, Elsevier, vol. 65(7), pages 1458-1465, October.
    8. Amy Finkelstein, 2007. "E-ZTax: Tax Salience and Tax Rates," NBER Working Papers 12924, National Bureau of Economic Research, Inc.
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    More about this item


    Introduction effect Timing of births Policy distortion;

    JEL classification:

    • H31 - Public Economics - - Fiscal Policies and Behavior of Economic Agents - - - Household
    • J13 - Labor and Demographic Economics - - Demographic Economics - - - Fertility; Family Planning; Child Care; Children; Youth


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