We evaluated pregnancy outcomes among women with hyperemesis gravidarum (HG) in a North London multi-ethnic population. A retrospective case-control study was performed on records of obstetric admissions during a 4-year period, at North Middlesex University Hospital in North London. A total of 208 women with HG were identified according to Fairweather's criteria occurring in the first 20 weeks of pregnancy, which is severe enough to require admission to hospital. The control study group consisted of 208 women without HG, matched for age, ethnicity and parity. Maternal characteristics as well as pregnancy outcomes were compared in the two groups. The incidence of a delivery of a small-for-gestational-age (SGA) neonate below the 10th per centile was significantly higher in the HG group compared with unaffected pregnancies (8.7% vs 16.8%, p = 0.01). Hyperemesis gravidarum in a multi-ethnic population in North London is associated with SGA neonates.