• Residential mobility;
  • follow-up studies;
  • pregnant women;
  • epidemiologic research design


Objective: To quantify the residential mobility rate in a population of pregnant women expecting their first baby.

Method: We verified residential mobility in a cohort of 585 primiparous Australian women who were enrolled in late pregnancy and had participated in a randomised controlled trial and followed-up to at least 16 weeks post-partum.

Results: We found a residential mobility rate of 19%. Movers and non-movers differed by socio-demographic factors, with movers more likely be younger, relative risk (RR)=2.14 (95% confidence interval (CI) 1.41-3.13), and not living with a partner RR=2.46 (95% CI 1.60-3.77).

Conclusion: Most prospective epidemiological studies can expect some attrition in the study population. The family formation period is acknowledged as a highly mobile time and this mobility may contribute to loss to follow-up.

Implications: Researchers planning prospective studies in pregnant populations should consider the impact of residential mobility, especially differential mobility, and implement strategies to reduce attrition and optimise response rates.