To investigate whether recurrent or persistent otitis media with effusion (OME) was associated with particular patterns of fetal growth, we conducted a case control study of 129 children admitted for insertion of grommets and 150 controls. The risk of OME was not statistically significantly related to gestational age or individual measures of size at birth, but the ratio of head circumference to total length and the ponderal index at birth were statistically significantly lower in children with OME, both before and after adjustment for the potentially confounding effects of sex, age at current operation, and maternal gravidity. Mothers of cases were 2.2 times more likely than those of controls to have had one or more previous pregnancies that had not ended in a live birth (95% CI 1.3-3.8). We conclude that fetal growth, reflected by proportions at birth, may affect later risk of recurrent and persistent OME.