Prevalence and factors associated with small for gestational age births among women delivering at a tertiary hospital in South-Western Uganda: a cross-sectional study

Small for Gestational Age (SGA) is defined as birthweight of a baby below the 10th percentile for a given gestational age. A baby is born SGA if they are constitutionally small or if they had intrauterine growth restriction and this is associated with neonatal morbidity and mortality. When measuring birthweight alone to predict early adverse neonatal outcomes, babies born with a normal birthweight and are SGA go unnoticed yet they are at risk of morbidity and mortality. This study aimed to determine the prevalence and factors associated with SGA births among women delivering at Mbarara Regional Referral Hospital. A cross-sectional study was conducted on mother-baby pairs at Mbarara Regional Referral Hospital (MRRH) from May to August 2023. Data on maternal, medical, socio-demographic and obstetric characteristics were collected. Babies whose birthweight was below the < 10th percentile for gestational age were classified as SGA using a WHO birthweight gestational age chart. The prevalence of SGA was the proportion of babies whose weights were less than 10th percentile expressed as a percentage of the total participants. A modified Poisson multivariable regression analysis was used to determine the factors associated with all SGA births. Variables with a p-value of < 0.05 were considered independently associated with SGA. A total of 427 mother-baby pairs were enrolled with a mean age of 26.6 (± 5.58) years. The prevalence of SGA was 21.8% (95% CI; 18.1% − 26.0%). Factors that were independently associated with SGA included; maternal > 34 years [aPR: 2.29; 95% CI (1.15–4.53), p = 0.018], maternal height < 150 cm [aPR: 2.18; 95% CI (1.26– 3.91), p = 0.005], history of a hypertensive disorder in current pregnancy [aPR: 2.18 (1.12–5.09), p = 0.039]. At MRRH, the prevalence of SGA is high. Factors that are associated with SGA include; advanced maternal age, short stature and a history of any hypertensive disorder in the current pregnancy. We recommend routine use of birthweight gestational age charts to screen for SGA especially among women of advanced age, short stature and those who are hypertensive.