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Convenience Effect on Birth Timing Manipulation: Evidence from Brazil

February 6, 2017

According to the United Nations Children’s Fund, Brazil ranked first place with the highest cesarean section rate among 139 countries in the world for the period of 2007-2012.[1] In 2009, the number of surgical births surpassed vaginal deliveries. During the years of 2012-2014, cesarean delivery (CD) corresponded to 57% of all registered births in the country. Another less but still invasive medical intervention is labor induction. This is a technique used to bring on or speed up contractions and thus anticipate vaginal births. For the period of 2012-2014, 33% of all registered normal deliveries in the country occurred after induced labor. Therefore, only 29 out of 100 births in Brazil occurred in the form of natural birth, through a spontaneous (non-induced) vaginal delivery.[2]

Such medical interventions (CD and labor induction) allow for manipulation in the timing of birth. Although birth timing can be altered due to medical reasons (e.g., when labor could be dangerously stressful or in case of post-term pregnancies), the existing evidence suggests that it is also manipulated for reasons other than the health of the fetus or of the mother. Mothers’ incentives to intervene in the timing of their deliveries are usually financial when compensations are involved, such as baby bonuses (Gans and Leigh, 2009) or tax savings (Dickert-Conlin and Chandra, 1999), or even related to cultural issues (Lo, 2003). Doctors’ incentives tend to be determined by risk-aversion (Fabbri et. al, 2015) or convenience (Gans et al., 2007).

As CD can be scheduled for medical reasons, a concentration of scheduled CD’s in convenient moments does not constitute enough evidence to suggest that deliveries are being scheduled due to convenience motivations. However, since complications during delivery that require an emergency CD should be randomly distributed across time, a concentration of unplanned CD’s during convenient times indicates that reasons other than the protocol are playing a role. Brown (1996) and Lefèvre (2014) show evidence on this matter. Both papers suggest that physicians induce CD in the labor room during convenient moments. Thus, physicians’ convenience motivations as well as other incentives correlated to convenient moments could be at play.

Convenient times usually coincide with times when it might be safer to deliver. It is also during non-leisure days and usual business hours that the largest capacity of hospital staff is on-shift and medical staff is fresher. If this is the case, then doctors who are risk-averse or altruistic might have preferences to allocate complex deliveries on those moments when risk can be minimized. Fabbri et al. (2015) provide evidence of risk aversion attitudes for a sample of women admitted at the onset of labor in a public hospital in Italy.

In my thesis from UFRJ, I tested whether convenience effects play any relevant role in birth-timing manipulation in Brazil. More specifically, I investigated if births that would have occurred after spontaneous labor during inconvenient times are anticipated to convenient times. I adopted several strategies in order to isolate the convenience effect from potential risk aversion attitude.

First, I used a new type of inconvenient days that may attenuate risk aversion attitudes in manipulating the timing of births: business days in-between holidays. As these are business days, hospitals should be fully-staffed. However, risk-averse physicians may still manipulate the timing of births in order to eliminate the possibility of women going spontaneously into labor on the surrounding leisure days. Second, I analyzed the results by hospital funding. Public funded hospitals provide a context where women do not actively participate in the decision-making process. This scenario enabled me to attribute the results to physicians. Third, I further investigated the results by level of risk. While birth timing manipulation motivated by convenience should happen mostly among low-risk births, timing manipulation guided by risk aversion should be concentrated in high-risk births – as in this latter case the goal is to minimize the risk of low quality hospital services.

Using daily data on birth records, I constructed a daily panel of number of deliveries by hospitals for the period 2012-2014, with information on hospitals, deliveries (e.g. type of birth procedure and nature of labor), pregnancy, mothers and newborns. Having classified births as low-risk and high-risk according to observable variables (e.g. mother’s age below 18 or above 35 years old, multiple pregnancy, newborn with congenital anomaly), I ended up with daily panels of number of high and low-risk deliveries by hospital.

As my goal was to understand if births that would have occurred after spontaneous labor were anticipated, I ran regressions of the number of births after spontaneous labor on days in-between holidays. I found a significant negative result, which suggests that either convenience or risk-aversion motivations were playing a role. Then, I verified that the results were robust to the restricted sample of public funded hospital. Hence, I attributed the results to physicians’ motivations. Finally, I further restricted the sample to low-risk births and re-estimated the results. Having found out that the findings were driven by low-risk deliveries provided further evidence that births were being anticipated due to physicians’ convenience effect. Moreover, I ran the same regressions for the days preceding the leisure period and verified an increase of cesarean sections, which reinforces the previous results that births that would otherwise have happened after spontaneous labor occurred instead by the scheduling of cesarean sections.

 

References

[1] http://data.un.org/Data.aspx?q=cesarean&d=SOWC&f=inID%3a219

[2] CD rates extracted from the Brazilian National System of Information on Birth Records (Datasus/SINASC).

Borra, C., González, L.; Sevilla, A. Birth timing and neonatal health. The American Economic Review, v. 106, n. 5, p. 329-332, 2016.

Borra, C., González, L.; Sevilla, A. The impact of scheduling birth early on infant health. Working Paper presented at Tinbergen Institute, 2016.

Gans, J.S.; Leigh, A. Born on the first of July: An (un)natural experiment in birth timing. Journal of Public Economics, v. 93, n. 1-2, p. 246-263, 2009.

Dickert-Conlin, S.; Chandra A. Taxes and the timing of births. Journal of Political Economy, v. 107, n. 1, p. 161-177, 1999.

Fabbri, D.; Castaldini, I.; Monfardini, C.; Protonotari, A., Caesarean section and the manipulation of exact delivery time. HEDG working paper n.15, University of York, 2015.

Gans, J.S.; Leigh, A.; Varganova, E. Minding the shop: The case of obstetrics conferences. Social Science and Medicine, v. 6, n. 7, p. 1458-1465, 2007.

Brown, H.S. Physician demand for leisure: Implications for cesarean section rates. Journal of Health Economics, v.15, p. 233-242, 1996.

Lefevre, M. Physician induced demand for C-sections: does the convenience incentive matter? HEDG working paper n. 14, University of York, 2014.

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