Association of socioeconomic status with adverse birth outcomes at the Women and Newborn Hospital of the University Teaching Hospitals in Lusaka, Zambia

Background: Low socioeconomic status has generally been associated with adverse birth outcomes worldwide. Adverse birth outcomes significantly contribute to perinatal morbidity and mortality worldwide with some literatures showing conflicting results. At Women and New-born Hospital in Zambia, this relationship had remained unclear among women who experienced poor neonatal outcome; hence the study was done to explore this association between socioeconomic status and adverse birth outcomes. Methods: A retrospective cohort study was conducted. Secondary data from ZAPPS study that had been collected prospectively between August 2015 and September 201 7 was retrieved. Altogether, 1,450 participants' information was retrieved, out of which 1,084 data records were set out for analysis after excluding those not meeting eligibility criteria. Socioeconomic status was an explanatory variable which was estimated using the standardized wealth score derived from principal component analysis of 14 variables. The wealth quintiles were further categorised into poor and not poor. Response variables were low birth weight, preterm birth and small for gestation age. SPSS version 21 was used for data analysis and p value< 0.05 was significant  Results: This study found the incidences of SGA, LBW and preterm births to be 164, 124 and 13 5 per 1000 live births respectively. In survival analysis, the proportion of babies who survived LBW among mothers who were poor was lower (82.9%) compared to babies born to rich mothers (87.5%) (p-value = 0.189). Furthermore, the proportion of babies who survived SGA for the poor was lower (79 .1 % ) compared to babies born to none poor mothers (85.8%) (p-value = 0.032) and preterm birth for the poor (78.4%) compared to babies born to mothers who were rich (83 .6%) (p-value = 0.022). In multiple Cox regression analysis socioeconomic status was not a significant risk factor for SGA ( aHR = 1.08; 95% CI; p=0.099), LBW and preterm birth (aHR = 1.17; 95% CI; p= l.41). However, male babies (aHR = 1.80; 95% CI; p=0.012), domestic violence or abuse during pregnancy (aHR = 3.48; 95% CI [1.59 - 7.34]; p = 0.002) and maternal anaemia (aHR = 2.1; 95% CI; p = 0.019) were risk factors for SGA while prior preterm birth ( aHR = 2.02; 95% CI; p = 0.002), HIV infection (aHR = 1.22; 95% CI; p = 0.040) and anaemia (aHR = 1.37; 95% CI; p = 0.009) were predictors of preterm delivery.  Conclusion: There was no statistically significant association between low socioeconomic status and adverse birth outcomes although being pregnant with a male baby, HIV infection, anaemia and prior preterm birth were significantly associated with SGAand preterm.