Birth Order and Infant Health: Evidence From Maternal Immunisation in New Zealand
Date
Authors
Schober, Thomas
Supervisor
Item type
Journal Article
Degree name
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier BV
Abstract
Immunisation during pregnancy is a vital strategy to protect infants from infectious diseases in their first months of life, yet little is known about how birth order relates to maternal vaccination uptake and infants’ risk of severe illness. Drawing on administrative data from New Zealand covering more than 200,000 births between 2015 and 2023, I analyse the relationship between birth order and maternal vaccination against pertussis and influenza. I also examine subsequent infant hospitalisations for these diseases. The findings show that later-born children experience higher hospitalisation rates, likely because of increased exposure to infectious diseases through older siblings. At the same time, maternal vaccination rates decline with each pregnancy, leaving those who would benefit most from maternal immunisation the least likely to receive it. These findings suggest that improving vaccination uptake during later pregnancies could yield important health gains for infants at highest risk.Description
Keywords
Birth order, Child health, Influenza, Maternal immunisation, Pertussis, 11 Medical and Health Sciences, 14 Economics, 16 Studies in Human Society, Public Health, 38 Economics, 42 Health sciences, 44 Human society
Source
Social Science and Medicine, ISSN: 0277-9536 (Print); 1873-5347 (Online), Elsevier BV, 401, 119352-. doi: 10.1016/j.socscimed.2026.119352
Publisher's version
Rights statement
© 2026 The Author. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)