Fertility and Well-Being

At a Glance Projects Publications Team


Consequences of Sibling Group Structure

Conducted by Mikko Myrskylä; Susie Lee, Kieron Barclay; in Collaboration with Anna Baranowska-Rataj (Umeå University, Sweden), Martin Kolk (Stockholm University, Sweden), Dalton Conley (Princeton University, USA), Lyngstad Torkild (University of Oslo, Norway), Katherine Keenan (University of St Andrews, United Kingdom), Alice Goisis (University College London, United Kingdom), Ken R. Smith (The University of Utah, Salt Lake City, USA)

Detailed Description

We focus on how fertility decisions made by parents, which affect sibling group structure and the early-life conditions experienced within the family, have a range of health, educational, and socioeconomic consequences for children, using registry or register-like data.

Previous research has suggested that short birth-spacing increases the risk of poor perinatal and poor long-term socioeconomic outcomes. Existing research has also shown that children without siblings as well as later-born siblings in multi-child sibling groups have worse long-term socioeconomic and health outcomes. It is thus important to understand how these various factors influence offspring outcomes.

Two of our new works have addressed the importance of family size during childhood for health and mortality, using Swedish population registers. We have found overall lower health and survival rates among only children compared to those who have one or two siblings. As yet, single children without half-siblings were consistently healthier than those with half-siblings, suggesting that parental disruption confers additional disadvantages. In another study, we used a novel approach – cousin fixed effects – to study whether birth order in the parental generation influences the educational attainment in the offspring generation. The method compares cousins who share the same biological grandparents and therefore adjusts for unobserved factors in the extended family.

We have also expanded our previous works on the health implications of birth intervals. Revisiting the question of the long-term consequences of short birth intervals and using the Utah Population Database, we have found that not even the very shortest birth intervals are negatively associated with educational or occupational outcomes or with long-term mortality. In another work, we have found that in a high-income country such as contemporary Sweden, neither short nor long birth intervals seem to have a negative effect on birth outcomes such as preterm birth and low birth weight; nor do birth intervals affect the probability of hospitalization during childhood. These findings challenge much of the previous work produced in similar high-income contexts, encouraging more research to be done to ascertain the long-term implications of birth intervals on offspring health.

Research Keywords:

Fertility Development, Health Care, Public Health, Medicine, and Epidemiology


Dierker, P.; Diewald, M.:
MPIDR Working Paper WP-2023-004. (2023)    
Keenan, K.; Barclay, K. J.; Goisis, A.:
Population Studies 77:1, 71–90. (2023)    
Howe, L. J.; Nivard, M. G.; Morris, T. T.; Hansen, A. F.; Rasheed, H.; Cho, Y.; Chittoor, G.; Ahlskog, R.; Lind, P. A.; Palviainen, T.; van der Zee, M. D.; Cheesman, R.; Mangino, M.; Wang, Y.; Li, S.; Klaric, L.; Ratliff, S. M.; Bielak, L. F.; Nygaard, M.; Giannelis, A.; Willoughby, E. A.; Reynolds, C. A.; Balbona, J. V.; Andreassen, O. A.; Ask, H.; Baras, A.; Bauer, C. R.; Boomsma, D. I.; Campbell, A.; Campbell, H.; Chen, Z.; Christofidou, P.; Corfield, E.; Dahm, C. C.; Dokuru, D. R.; Evans, L. M.; de Geus, E. J. C.; Giddaluru, S.; Gordon, S. D.; Harden, K. P.; Hill, W. D.; Hughes, A.; Kerr, S. M.; Kim, Y.; Kweon, H.; Latvala, A.; Lawlor, D. A.; Li, L.; Lin, K.; Magnus, P.; Magnusson, P. K. E.; Mallard, T. T.; Martikainen, P.; Mills, M. C.; Njølstad, P. R.; Overton, J. D.; Pedersen, N. L.; Porteous, D. J.; Reid, J.; Silventoinen, K.; Southey, M. C.; Stoltenberg, C.; Tucker-Drob, E. M.; Wright, M. J.; Social Science Genetic Association Consortium within Family Consortium; Hewitt, J. K.; Keller, M. C.; Stallings, M. C.; Lee, J. J.; Christensen, K.; Kardia, S. L. R.; Peyser, P. A.; Smith, J. A.; Wilson, J. F.; Hopper, J. L.; Hägg, S.; Spector, T. D.; Pingault, J.; Plomin, R.; Havdahl, A.; Bartels, M.; Martin, N. G.; Oskarsson, S.; Justice, A. E.; Millwood, I. Y.; Hveem, K.; Næss, Ø. E.; Willer, C. J.; Åsvold, B. O.; Koellinger, P. D.; Kaprio, J.; Medland, S. E.; Walters, R. G.; Benjamin, D. J.; Turley, P.; Evans, D. M.; Smith, G. D.; Hayward, C.; Brumpton, B.; Hemani, G.; Davies, N. M.:
Nature Genetics 54:5, 581–592. (2022)    
Barclay, K. J.; Lyngstad, T. H.; Conley, D.:
European Sociological Review 37:4, 607–625. (2021)    
Grätz, M.; Barclay, K. J.; Wiborg, Ø.; Lyngstad, T. H.; Karhula, A.; Erola, J.; Präg, P.; Laidley, T.; Conley, D.:
Demography 58:3, 1011–1037. (2021)    
Barclay, K. J.; Baranowska-Rataj, A.; Kolk, M.; Ivarsson, A.:
Population Studies 74:3, 363–378. (2020)    
Gabay-Egozi, L.; Grieger, L.; Nitsche, N.:
MPIDR Working Paper WP-2020-031. (2020)    
Keenan, K.; Barclay, K. J.; Goisis, A.:
MPIDR Working Paper WP-2020-004. (2020)    
Spilerman, S.; Barclay, K. J.:
MPIDR Working Paper WP-2020-017. (2020)    
Molitoris, J.; Barclay, K. J.; Kolk, M.:
Demography 56:4, 1349–1370. (2019)    
Barclay, K. J.:
Research in Social Stratification and Mobility 54, 56–65. (2018)    
Barclay, K. J.; Kolk, M.:
Demography 55:3, 929–955. (2018)    
Baranowska-Rataj, A.; Barclay, K. J.; Kolk, M.:
Population Studies 71:1, 43–63. (2017)    
Barclay, K. J.; Hällsten, M.; Myrskylä, M.:
Social Forces 96:2, 629–660. (2017)    
Barclay, K. J.; Myrskylä, M.; Tynelius, P.; Berglind, D.; Rasmussen, F.:
Drug and Alcohol Dependence 167, 15–22. (2016)    
Barclay, K. J.; Myrskylä, M.:
Social Science and Medicine 123, 141–148. (2014)    
The Max Planck Institute for Demographic Research (MPIDR) in Rostock is one of the leading demographic research centers in the world. It's part of the Max Planck Society, the internationally renowned German research society.