Neighborhood Income Mobility and Risk of Neonatal and Maternal Morbidity

Residing in a low-income neighborhood is generally associated with worse pregnancy outcomes. It is not known if moving from a low- to higher-income area between 2 pregnancies alters the risk of adverse birth outcomes in the subsequent birth compared with women who remain in low-income areas for both births.

To compare the risk of adverse maternal and newborn outcomes among women who achieved upward area-level income mobility vs those who did not.

This population-based cohort study was completed in Ontario, Canada, from 2002 to 2019, where there is universal health care. Included were all nulliparous women with a first-time singleton birth at 20 to 42 weeks' gestation, each residing in a low-income urban neighborhood at the time of the first birth. All women were then assessed at their second birth. Statistical analysis was conducted from August 2022 to April 2023.

Movement from a lowest-income quintile (Q1) neighborhood to any higher-income quintile neighborhood (Q2-Q5) between the first and second birth.

The maternal outcome was severe maternal morbidity or mortality (SMM-M) at the second birth hospitalization or up to 42 days post partum. The primary perinatal outcome was severe neonatal morbidity or mortality (SNM-M) within 27 days of the second birth. Relative risks (aRR) and absolute risk differences (aARD) were estimated by adjusting for maternal and infant characteristics.

A total of 42 208 (44.1%) women (mean [SD] age at second birth, 30.0 [5.2] years) experienced upward area-level income mobility, and 53 409 (55.9%) women (age at second birth, 29.0 [5.4] years) remained in income Q1 between births. Relative to women who remained in income Q1 between births, those with upward mobility had a lower associated risk of SMM-M (12.0 vs 13.3 per 1000 births), with an aRR of 0.86 (95% CI, 0.78 to 0.93) and aARD of -2.09 per 1000 (95% CI, -3.1 to -0.9 per 1000 ). Likewise, their newborns experienced lower respective rates of SNM-M (48.0 vs 50.9 per 1000 live births), with an aRR of 0.91 (95% CI, 0.87 to 0.95) and aARD of -4.7 per 1000 (95% CI, -6.8 to -2.6 per 1000).

In this cohort study of nulliparous women living in low-income areas, those who moved to a higher-income area between births experienced less morbidity and death in their second pregnancy, as did their newborns, compared with those who remained in low-income areas between births. Research is needed to determine whether financial incentives or enhancement of neighborhood factors can reduce adverse maternal and perinatal outcomes.