Low birthweight is associated with increased infant morbidity, poorer developmental outcomes and risk of adult disease and its prevention remains a public health priority. South Asian children are more likely to be born small and there is some debate around whether this is a normal phenomenon within this population or whether they have a greater risk of morbidity. We examined the association between small size at birth and morbidity in White British and Pakistani origin children aged 0–3 participating in the Born in Bradford cohort study. We included 4119 White British and 4731 Pakistani origin children and examined health service use (General Practitioner (GP) consultations, the most common prescribing categories (analgesics, antibiotics, bronchodilators), emergency and elective hospital episodes) as markers of morbidity, in children born small defined as: (i) low birthweight (< 2500 g) (ii) small for gestational age (SGA) using customised birth charts. We used negative binomial regression models to predict the adjusted incidence of morbidity markers. 8.7% of Pakistani and 5% of White British children were born with a low birthweight (< 2500 g). Using customised charts, these proportions were 15.3 and 6.2% respectively. Children born small in both groups irrespective of the criteria used, generally had a higher rate of episodes for morbidity markers compared to normal weight children. Incidence of GP consultations (IRR 1.48 (95% CI 1.27, 1.73) to 1.55 (95% CI 1.36, 1.76) depending on birthweight category), analgesic (IRR 1.76 (95% CI 1.37, 2.25) to 2.31 (95% CI 2.19, 2.45) and antibiotic prescriptions (IRR 1.13 (95% CI 0.08, 1.46) to 1.38 (95% CI 1.30, 1.48) and emergency hospital episodes (IRR 1.20 (95% CI 1.06, 1.36) to 1.46 (95% CI 0.92, 2.32), was higher in Pakistani origin children with either a low or normal birthweight. Being born small is associated with greater morbidity estimated by use of health services, in both White British and Pakistani origin children underlining the importance of public health policy to reduce low birthweight. Pakistani origin children access health services more frequently than White British children irrespective of birthweight and this has implications for health service planning in areas with South Asian populations.