Marcos Vera-Hernández
Emla Fitzsimons
José V. Rodríguez Mora
Tomasa Rodrigo
Álvaro Ortiz
Stephen Hansen
Vasco Carvalho
Gergely Buda
Gabriel Zucman
Anders Jensen
Matthew Fisher-Post
José-Alberto Guerra
Myra Mohnen
Christopher Timmins
Ignacio Sarmiento-Barbieri
Peter Christensen
Linda Wu
Gaurav Khatri
Julián Costas-Fernández
Eleonora Patacchini
Jorgen Harris
Marco Battaglini
Ricardo Fernholz
Alberto Bisin
Jess Benhabib
Cian Ruane
Pete Klenow
Mark Bils
Peter Hull
Will Dobbie
David Arnold
Eric Zwick
Owen Zidar
Matt Smith
Ansgar Walther
Tarun Ramadorai
Paul Goldsmith-Pinkham
Andreas Fuster
Ellora Derenoncourt
Golvine de Rochambeau
Vinayak Iyer
Jonas Hjort
Elena Simintzi
Paige Ouimet
Holger Mueller
Pablo Garriga
Gabriel Ulyssea
Costas Meghir
Pinelopi Koujianou Goldberg
Rafael Dix-Carneiro
Alessandro Toppeta
Áureo de Paula
Orazio Attanasio
Seth Zimmerman
Joseph Price
Valerie Michelman
Camille Semelet
Anne Brockmeyer
Pierre Bachas
Santiago Pérez
Elisa Jácome
Leah Boustan
Ran Abramitzky
Jesse Rothstein
Jeffrey T. Denning
Sandra Black
Wei Cui
Mathieu Leduc
Philippe Jehiel
Shivam Gujral
Suraj Sridhar
Attila Lindner
Arindrajit Dube
Pascual Restrepo
Łukasz Rachel
Benjamin Moll
Kirill Borusyak
Michael McMahon
Frederic Malherbe
Gabor Pinter
Angus Foulis
Saleem Bahaj
Stone Centre
Phil Thornton
James Baggaley
Xavier Jaravel
Richard Blundell
Parama Chaudhury
Dani Rodrik
Alan Olivi
Vincent Sterk
Davide Melcangi
Enrico Miglino
Fabian Kosse
Daniel Wilhelm
Azeem M. Shaikh
Joseph Romano
Magne Mogstad
Suresh Naidu
Ilyana Kuziemko

Breastfeeding and child development

What is this research about and why did you do it?

This research estimates the effect of breastfeeding on child development: cognitive and socio-emotional, as well as health. Breastfeeding is just one of many ways in which mothers can influence their child’s development, and mothers who breastfeed may also be more or less likely to make other investments that affect their child’s development. Although there is much research on breastfeeding, most previous work does not isolate the effect of breastfeeding from these other investments undertaken by families.

How did you answer this question?

Our research found that, among a sample of low educated mothers, babies born just before or during the weekend were less likely to be breastfed compared to those born on weekdays, because UK hospitals reduce breastfeeding support at weekends. This allowed us to disentangle the effect of breastfeeding from other investments that improve child development, because mothers do not choose when to give birth, so the costs of other investments are uncorrelated with timing of birth. We combined this observation with the Millennium Cohort Study dataset, collected by the UCL Centre for Longitudinal Studies, which follows children born between 2000-02 and collects data on their development (including cognitive tests) every two to four years.

What did you find?

We found that breastfeeding for at least 90 days improves children’s cognitive development by around 0.46 standard deviations on average between ages 3 and 7, 95% confidence interval (+0.1 ; 0.82). Concerning the effects on socio-emotional development and health, our estimates are not statistically different from zero, though the confidence intervals are wide.

On the horizontal axis, 0 refers to birth deliveries taking place on Mondays at 00:01am, and 168 to those taking place on Sundays at 23:59 pm. The probability of breastfeeding(solid dotted line, measured in the right vertical axis) decreases with the proximity to the weekend. The average value of the child’s cognitive development according to timing of birth (solid line, measured in the left vertical axis) tracks how the probability of breastfeeding evolves with timing of birth, indicating a causal link between timing of birth, probability of breastfeeding, and child’s cognitive development. The predictive index (light grey dotted line), which only depends on the child’s and mother’s observed characteristics, does not track the probability of breastfeeding, confirming the validity of our research design as it shows that the relation between timing of birth, probability of breastfeeding, and child’s cognitive development is not due to differences in mothers’ and children’s observable characteristics.

What implications does this have for the research on wealth concentration or economic inequality?

Breastfeeding is far more common amongst highly educated mothers: according to the 2010 UK Infant Feeding Survey, 56% of mothers who left full-time education at 19 or over breastfed their children for at least four months, compared to 22% of mothers who left full-time education at age 16 or before. Given our new evidence that breastfeeding improves children’s cognitive development, it may be an important contributor to the inter-generational transmission of human capital and the perpetuation of inequalities therein.

What are the next steps in your agenda?

A vital question is whether the strong effects on cognition persist or fade out as children get older. We plan to estimate the longer-term effect of breastfeeding on children’s academic attainment, using data from formal school assessments, the General Certificate of Secondary Education (GCSE), which students sit at 16 years of age. We will use the linkage between the Millennium Cohort Study database and National Pupil Database administrative records for this.

Citation and related resources

This paper can be cited as follows: Fitzsimons, E., and Vera-Hernández, M. 2022. 'Breastfeeding and Child Development.' American Economic Journal: Applied Economics, 14(3), pp. 329-66.

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About the authors

Marcos Vera-Hernández
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