Mothers with higher twinning propensity had lower fertility in pre-industrial Europe

Rickard, Ian J.; Vullioud, Colin; Rousset, François; Postma, Erik; Helle, Samuli; Lummaa, Virpi; Kylli, Ritva; Pettay, Jenni E.; Røskaft, Eivin; Skjærvø, Gine R.; Störmer, Charlotte; Voland, Eckart; Waldvogel, Dominique; Courtiol, Alexandre

doi:10.1038/s41467-022-30366-9

Mothers with higher twinning propensity had lower fertility in pre-industrial Europe

Rickard, Ian J.; Vullioud, Colin; Rousset, François; Postma, Erik; Helle, Samuli; Lummaa, Virpi; Kylli, Ritva; Pettay, Jenni E.; Røskaft, Eivin; Skjærvø, Gine R.; Störmer, Charlotte; Voland, Eckart; Waldvogel, Dominique; Courtiol, Alexandre

Authors

Ian J. Rickard

Colin Vullioud

François Rousset

Erik Postma

Samuli Helle

Virpi Lummaa

Ritva Kylli

Jenni E. Pettay

Eivin Røskaft

Gine R. Skjærvø

Charlotte Störmer

Eckart Voland

Dominique Waldvogel

Alexandre Courtiol

Abstract

Historically, mothers producing twins gave birth, on average, more often than non-twinners. This observation has been interpreted as twinners having higher intrinsic fertility – a tendency to conceive easily irrespective of age and other factors – which has shaped both hypotheses about why twinning persists and varies across populations, and the design of medical studies on female fertility. Here we show in >20k pre-industrial European mothers that this interpretation results from an ecological fallacy: twinners had more births not due to higher intrinsic fertility, but because mothers that gave birth more accumulated more opportunities to produce twins. Controlling for variation in the exposure to the risk of twinning reveals that mothers with higher twinning propensity – a physiological predisposition to producing twins – had fewer births, and when twin mortality was high, fewer offspring reaching adulthood. Twinning rates may thus be driven by variation in its mortality costs, rather than variation in intrinsic fertility.

Citation

Rickard, I. J., Vullioud, C., Rousset, F., Postma, E., Helle, S., Lummaa, V., Kylli, R., Pettay, J. E., Røskaft, E., Skjærvø, G. R., Störmer, C., Voland, E., Waldvogel, D., & Courtiol, A. (2022). Mothers with higher twinning propensity had lower fertility in pre-industrial Europe. Nature Communications, 13(1), https://doi.org/10.1038/s41467-022-30366-9

Journal Article Type	Article
Acceptance Date	Apr 27, 2022
Online Publication Date	May 24, 2022
Publication Date	2022
Deposit Date	Jul 19, 2022
Publicly Available Date	Jul 19, 2022
Journal	Nature Communications
Publisher	Nature Research
Peer Reviewed	Peer Reviewed
Volume	13
Issue	1
DOI	https://doi.org/10.1038/s41467-022-30366-9
Public URL	https://durham-repository.worktribe.com/output/1197470

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