Table 2

Maternal smoking

Maternal smokingaCaseControlORb95% CI
n%n%
Lifetime
Never29959.731161.81.0
Ever20240.319238.21.00.7–1.3
Around pregnancyc
Never35170.137173.81.0
Ever15029.913226.21.10.8–1.4
1 mo before conception
Never35470.737173.81.0
Ever14729.313226.21.10.8–1.4
1st trimester
Never39077.840179.71.0
Ever11122.210220.31.00.7–1.3
2nd trimester
Never41482.642183.71.0
Ever8717.48216.30.90.7–1.3
3rd trimester
Never41081.242183.71.0
Ever9118.28216.31.00.7–1.4
Breastfeeding
Never36492.237790.81.0
Ever317.9389.20.90.5–1.5
Cigarettes/day during 1st trimester
Nonsmoker39078.040179.91.0
≤5224.4255.00.80.5–1.5
5–10397.8346.81.00.6–1.6
10–15122.491.81.20.5–3.0
>15377.4336.60.90.6–1.6
Cigarettes/day during 2nd trimester
Nonsmoker41482.842184.01.0
≤5173.4163.21.00.5–2.0
5–10346.8306.01.00.6–1.6
10–15112.271.41.30.5–3.5
>15244.8275.40.80.4–1.4
  • a A total of three cases and one control had missing smoking-history information.

  • b Adjusted for child’s gender, mother’s race and education, and household income in the birth year.

  • c Included 1 month before and during the pregnancy and during breastfeeding.