TABLE 1

Developmental Delay in 9-Month-Old Infants of the Millennium Cohort by Biological, Socioeconomic, and Psychosocial Factors

FactornaGross Motor Delay,b %Fine Motor Delay,b %
Mother's age at birth, y
    14–1913176.99.7
    20–2972968.76.4
    30–3965899.15.2
    40+31511.74.4
Birth weight, g
    2500–2999240910.66.5
    3000–349961999.66.9
    3500–399948588.05.4
    >400020566.74.6
Gestation, wk
    37–38292911.56.9
    39–4084108.66.2
    >4041837.45.0
Smoking during pregnancy
    None123518.65.8
    1–10/d23919.26.8
    >10/d78011.97.2
Social class
    Higher professional/managerial18699.14.8
    Lower professional/managerial28867.75.0
    Intermediate occupations11787.05.7
    Small employers and self employed15358.35.8
    Lower supervisory and technical19728.34.8
    Semiroutine occupations258310.08.0
    Routine occupations25179.57.1
    Unclassifiable98212.710.4
Mother’s educational qualifications
    Level 0242712.89.8
    Level 1131412.27.1
    Level 244787.55.3
    Level 322177.55.4
    Level 440467.75.1
    Level 553510.95.2
    Other48012.59.7
Mother's employment status
    Full-time work23287.45.2
    Part-time work43887.65.2
    Nonworking88039.96.7
Partnership status
    Partnered128998.85.7
    Lone parent26239.18.3
No. of siblings
    063718.05.9
    154598.76.1
    2 or more369210.66.2
Care while working
    Parents18187.35.5
    Relative26567.35.3
    Nursery10207.84.1
    Other10888.45.9
    Not applicable89089.96.7
Cared for by others, h/wk
    081041.06.8
    1–107177.34.4
    11–2025557.95.5
    21–3019087.65.2
    31–4018337.55.2
    41–503018.96.9
    >50735.13.6
MeanMean
Malaise scale14 941
    No delay1.561.55
    Delay1.651.94
Postnatal attachment scale15 030
    No delay51.3251.35
    Delay50.9250.34
Attitude toward stimulating infant14 906
    No delay1.391.39
    Delay1.431.55
Attitude toward cuddling infant15 024
    No delay1.171.17
    Delay1.211.25
Attitude toward talking to infant15 019
    No delay1.181.17
    Delay1.221.27
  • a Actual (unweighted) sample size. May not sum to 15522 because of missing data.

  • b Weighted percentages and means.