Determinants of small for gestational age among HIV exposed infants delivered at the Women and Newborn hospital, Lusaka, Zambia

Objectives:  To explore the factors that influence small for gestational age outcome among HIV exposed infants delivered at the Women and Newborn Hospital, Lusaka, Zambia. Materials and Methods: This was a facility-based unmatched case control study nested in the Zambia Preterm Birth Prevention Study (ZAPPS) conducted at the Women and Newborn Hospital in Lusaka district between October 2017 and February 2021. Convenience sampling was used to select all the 53 HIV exposed small for gestational age infants (as cases) and 152 HIV unexposed small for gestational age infants (as controls). An excel data extraction tool was used to extract categorised variables from the ZAPPS data set into Stata version 19. Chi-square test was used to test for association, foetal and maternal variables with a p-value of 0.2 at univariate analyses were entered into a multiple logistic regression model. Results: The proportion of SGA, though not statistically significant, was found to be 19.9% among the HIV exposed infants compared to 17.3% in the unexposed group (p= 0.34). More than three quarters of participants in both the HIV positive arm (71.7%) and HIV negative arm (81.3%) were aged between 20-35 years. On multivariate analysis, Maternal chronic illness [AOR: 4.39, 95% CI: (1.66 - 11.6), p=0.003] and spontaneous preterm delivery [AOR: 1.58, 95% CI: (1.02 - 2.46), p=0.040] had a strong association with small for gestational age. Tertiary Level of education [AOR: 0.45, (0.24 - 0.85), p=0.014] was found to be significantly protective against small for gestational age. Maternal factors such as married status [AOR: 0.74, (0.48 - 1.13), p=0.164], secondary level of education [AOR: 0.82, (0.54 - 1.24), p=0.743], history of stillbirth [AOR: 1.31, (0.92-1.85), p=0.123] and the Mid-upper arm circumference [AOR: 0.96, (0.92-1.00), p=0.064] was not associated with small for gestational age.   Conclusion: There was no association between maternal HIV infection and SGA. Maternal chronic illness and spontaneous preterm birth increase the odds of SGA outcome while tertiary level of education is protective. Further research is needed to broaden the evidence base for addressing small for gestational age as a gateway to improve perinatal mortality, and for policy implementers to devise cost-effective and sustainable ways of reaching the at-risk population.