Stillbirth: are we making more progress than we think? A retrospective cohort study

Area of Science:

• Perinatal epidemiology
• Reproductive health research
• Public health surveillance

Background:

• Stillbirth rates are a key indicator of perinatal health.
• Maternal demographics have significantly shifted over recent decades.
• Understanding these shifts is crucial for accurate interpretation of stillbirth trends.

Purpose of the Study:

• To quantify the impact of evolving maternal risk profiles on stillbirth rate interpretation.
• To assess how changes in maternal characteristics influence the observed stillbirth rate.
• To determine if population stillbirth reductions have been underestimated due to demographic changes.

Main Methods:

• Retrospective population-based cohort study (1983-2018) of 2,419,923 births in Victoria, Australia.
• Analysis of changes in maternal characteristics over time.
• Development of a multivariable logistic regression model for stillbirth based on early data, applied prospectively to assess demographic impact.

Main Results:

• Despite a more complex maternal risk profile in 2014-2018 (older mothers, increased nulliparity, indigenous status, multiple pregnancies, pre-existing diabetes), the stillbirth rate decreased from 5.42 to 1.72 per 1000 births.
• Without accounting for demographic shifts, the stillbirth rate would have paradoxically increased by 12% (from 4.94 to 5.54 per 1000) between 1983 and 2018.
• Population reductions in stillbirth have been underestimated due to these demographic changes.

Conclusions:

• Population stillbirth rates are declining more rapidly than appreciated.
• The changing maternal demographic profile has masked the true extent of stillbirth reduction.
• Accurate interpretation of stillbirth rates requires accounting for evolving maternal characteristics.