Table 3 Comparisons of study samples and non-participants
Pregnancy | sample | Postnatal | sample | |||
|---|---|---|---|---|---|---|
Study sample | Non-participants | p-value | Study sample | Non-participants | p-value | |
Average 5-y road traffic noise (SD), n | 54.1 (7.4), n = 1384 | 55.1 (7.6), n = 4834 | <.0001 | |||
Road traffic noise at age 8 (SD), n | 53.1 (7.8), n = 1384 | 53.9 (8.2), n = 5484 | .001 | |||
Road traffic noise, pregnancy (SD), n | 55.8 (8.3), n = 1934 | 56.6 (8.4), n = 6425 | .0001 | |||
Average 5-y income (SD), n | 992,139 (540759), n = 1384 | 901,693 (580480) n = 7579 | <.0001 | |||
Income at age 8 (SD), n | 1,046,052 (621477), n = 1384 | 948,394 (678449) n = 7719 | <.0001 | |||
Income, pregnancy (SD), n | 786,438 (573046), n = 1934 | 767,439 (587234), n = 9688 | .19 | |||
Mother’s education, n | n = 1934 | n = 10,036 | n = 1384 | n = 10,586 | ||
> 4 years univ./college | 37.0 | 33.5 | <.001 | 41.6 | 33.1 | <.001 |
≤ 4 years univ./college | 49.9 | 47.1 | 45.3 | 47.8 | ||
High school | 13.1 | 19.4 | 13.1 | 19.1 | ||
Ethnicity, % western, n | 93.7, n = 1934 | 86.6, n = 10,148 | <.001 | 91.3, n = 1384 | 87.3, n = 10,698 | <.001 |
Gender, % boys, n | 49.5, n = 1934 | 50.9, n = 10,206 | .26 | 50.4, n = 1384 | 50.7, n = 10,756 | .81 |
Maternal smoking, pregnancy, % yes | 3.9, n = 1934 | 4.8n n = 8871 | .12 | 4.2, n = 1384 | 4.7, n = 9421 | .44 |
Maternal alcohol consumption, pregnancy, % yes | 7.2, n = 1934 | 7.3, n = 7278 | .98 | 9.5, n = 1384 | 6.9, n = 7828 | <.001 |
% birth weight < 2500 g, n | 2.8, n = 1934 | 3.2, n = 10,202 | .33 | 3.5, n = 1384 | 3.1, n = 10,752 | .37 |
% premature, n | 4.3, n = 1934 | 4.7, n = 10,192 | .39 | 4.5, n = 1384 | 4.7, n = 10,742 | .73 |