Scottish Longitudinal Study
Development & Support Unit

Current Projects

Project Title:

Understanding Recent Fertility Trends in the UK and Improving Methodologies for Fertility Forecasting

Project Number:



Dr. Sindhu Vasireddy, University of St Andrews
Prof. Ann Berrington, University of Southampton
Prof. Hill Kulu, University of St Andrews
Dr. Bernice Kuang, University of Southamptom

Start Date:



The aims of this research project are to examine the significant fluctuations in fertility levels in the UK in the last two decades, to investigate their causes, and to develop improved methodologies for fertility forecasting.

Using high-quality large-scale longitudinal data the project will, first, investigate childbearing trends by birth order in the UK in the last two decades to determine whether the increase and subsequent decline in the Total Fertility Rate (TFR) is attributable to the changes in first, second, third or higher-order births, or all of them. We also investigate whether differences in the TFR between the UK’s constituent countries are the result of differences in the timing of childbearing, variations in levels of childlessness, or different family sizes among mothers.

Second, the project will examine how much of the recent fluctuations in period fertility can be explained by the changes in fertility timing (i.e. women having children later or earlier in their lives), changes in population composition (e.g. increasing number of immigrants and their descendants), or changes in fertility behaviour (i.e. women have fewer or more children).

Third, we will investigate whether certain sub-populations (e.g. educational groups) have changed their fertility behaviour more than others. We will assess whether the empirical evidence is consistent with theoretical expectations on the role that wider social changes, including the family policies introduced in the UK in the late 1990s and economic recession, play in changing fertility levels in the first decades of the 21st century.

Fourth, we will also examine how individuals’ health influences their fertility behaviour using information on self-reported health from the UK’s censuses linked to longitudinal studies.

Finally, the project will propose a novel method to forecast future fertility in the UK. The forecast will draw on the analysis of fertility trends by birth order and will include uncertainty in fertility projections.


Andersson, G. 1999. Childbearing trends in Sweden 1961–1997, European Journal of Population 15(1): 1–24. Berrington, A., J. Stone and E. Beaujouan. 2015. Educational differences in timing and quantum of childbering in Britain: A study of cohorts born 1940–1969, Demographic Research 33(26): 733–764. Berrington, A. and J. Stone. 2017. Understanding third and fourth births in Britain: What role do increased immigration and multiple partnerships play? CPC Working Paper 83, ESRC Centre for Population Change, UK. Bongaarts, J. and T. Sobotka. 2012. A demographic explanations for the recent rise in European fertility, Population and Development Review 38(1): 83–120. Frejka, T. and T. Sobotka. 2008. Fertility in Europe: diverse, delayed and below replacement, Demographic Research 19(3): 15–46. Hoem, J. M. 1987. Statistical analysis of a multiplicative model and its application to the standardization of vital rates: a review, International Statistical Review 55(2): 119–152. Kneale, D. and H. Joshi. 2008. Postponement and childlessness: evidence from the two British cohorts, Demographic Research 19(58): 1935–1968. Kulu, H., and E. Washbrook. 2014. Residential context, migration and fertility in a modern urban society, Advances in Life Course Research, 21: 168–182. Kulu, H., T. Hannemann, A. Pailhé, K. Neels, S. Krapf, A. González-Ferrer and G. Andersson. 2017. Fertility by birth order among the descendants of immigrants in selected European countries, Population and Development Review 43(1): 31–60. Murphy, M. and A. Berrington. 1993. Construction period parity progression ratios from houshold survey data. In M. Ní Bhrolcháin (ed.), New Perspectives of Fertility in Britain. London: HMSO, pp. 17–33. Ní Bhrolcháin, M. 1987. Period parity progression ratios and birth intervals in England and Wales, 1941–1971: a synthetic life table analysis, Population Studies 41(1): 103–125. Ní Bhrolcháin, M. and E. Beaujouan. 2012. Fertility postponement is largely due to rising educational enrolment, Population Studies 66(3):

311–327. Robards, J. and A. Berrington. 2016. The fertility of recent migrants to England and Wales, Demographic Research 34(36): 1037–1052. Schmertmann, C., E. Zagheni, J.R. Goldstein, and M. Myrskylä. 2014. Bayesian forecasting of cohort fertility, Journal of the American Statistical Association 109(506): 500–513. Sigle, W. 2016. Fertility and population change in the United Kingdom. In R.R. Rindfuss and M.K. Choe (Eds.), Low Fertility, Institutions, and their Policies, pp. 77–98. Dortrecht: Springer. Smallwood, S. 2002. New estimates of trends in births by birth order in England and Wales, Population Trends 108: 32–48. Sobotka, T., V. Skirbekk and D. Philipov. 2011. Economic recession and fertility in the developed World, Population and Development Review 37(2): 267–306. Tromans, N., E. Natamba and J. Jefferies. 2009. Have women born outside the UK driven the rise in UK births since 2001, Population Trends 136: 28–42. Wellings, K., M. J. Palmer, R. S. Geary, L. J. Gibson, A. Copas, J. Datta, A. Glasier, R. H. Scott, C. H. Mercer, B. Erens, W. Macdowall, R. S. French, K. Jones, A. M. Johnson, C. Tanton and P. Wilkinson. 2016. Changes in conceptions in women younger than 18 years and the circumstances of young mothers in England in 2000–12: an observational study, Lancet 388: 586–595. Wiśniowski, A., P.W.F. Smith, J. Bijak, J. Raymer, and J.J. Forster. 2015. Bayesian population forecasting: extending the Lee-Carter method, Demography 52(3): 1035–1059.

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