Comparisons between the recruited sample and external data.

Notes to table: No correction taken for multiple comparisons.1Deprivation (Townsend) scores, ranks and fifths are based on geographical area of residence, using Lower Super Output Areas (LSOAs) defined by postcodes. This measure of material deprivation is calculated from rates of unemployment, vehicle ownership, home ownership, and overcrowding [49].2In five cases, both parents were students, and ONS categories could not be allocated. Fathers’ occupations taken where no occupation for mother [44], [49].3as reported by mothers at recruitment at 36 weeks’ pregnancy.4as in hospital records.5unequal sample sizes, unequal variances.