Social Inequalities in Infant Mortality Related to Congenital Anomalies: A Population-Based Register Study.

BACKGROUND

Infant mortality has recently increased in France, especially in deprived areas. Congenital anomalies (CA) are a major cause of infant mortality and could contribute to these trends.

OBJECTIVES

This study aimed to investigate socio-spatial inequalities in infant mortality associated with CA. It also examined socio-spatial differences in antenatal detection.

METHODS

We included all live births ≥ 22 weeks with CA from the Paris Registry of CA (remaPAR). Births are linked to infant deaths < 1 year using vital statistics records. A case-population design was applied to assess the association between an area-based deprivation score, assigned at the smallest census tract level (IRIS) of the mother's place of residence, and risks of infant death and live birth with CA. In the absence of data on births at the IRIS level, we used an aggregated population comparison group of children < 2 years old in 2019-2022 census data. We computed unadjusted odds ratios (OR) by comparing the distribution of the area-based score in quartiles in the case and census comparison populations. We also compared antenatal detection of CA by deprivation quartile.

RESULTS

The study included 2539 live births, resulting in 81 infant deaths. The proportions of infant deaths with CA were 39.5% and 16.0% in the most and least deprived quartiles, respectively, yielding an OR of 2.43 (95% confidence interval [CI] 1.28, 4.63). For live births with CA, these percentages were 29.7% and 22.0% with an OR of 1.34 (95% CI 1.20, 1.49). No variation across quartiles was observed in antenatal detection of CA, with a detection rate of 56.0% for live births and 85.2% for infant deaths. First-trimester ultrasound use was high (90.5%) but was lower in the most compared to the least deprived quartile (87.8% and 93.9%, respectively); however, second-trimester ultrasound use was similar across quartiles.

CONCLUSIONS

Area-based deprivation was associated with higher risks of infant mortality and live birth with CA, but not antenatal detection of CA. These results raise questions about differences in CA aetiology and decision-making about termination of pregnancy after CA detection.