TABLE 1.
Distribution and Respective Odds of US Youth Smoking Trajectories by Prenatal and Postnatal Exposure to Maternal Smoking: NLSY79-CYA, 1994–2006
| Youth Smoking Trajectory-Weighted Frequencies |
Smoking Trajectories UOR (95% CI) |
|||||||||
| Characteristics | Early Onset, % (No.) | Early Experiment, % (No.) | Late Onset, % (No.) | Nonsmoker, % (No.) | Total, % (No.) | Early Onset vs Nonsmoker, UOR (95% CI) | Early Experiment vs Nonsmoker, UOR (95% CI) | Late Onset vs Nonsmoker, UOR (95% CI) | Early Onset vs Late Onset, UOR (95% CI) | Early Experiment vs Late Onset, UOR (95% CI) |
| Total sample | 14.7 (633) | 2.7 (127) | 18.8 (958) | 63.7 (3309) | 100.0 (5027) | |||||
| Mother ever smoked | ||||||||||
| Never daily (Ref) | 8.7 (202) | 1.8 (48) | 15.1 (385) | 74.4 (1854) | 100.0 (2489) | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| Ever daily | 19.7 (431) | 3.5 (79) | 21.9 (573) | 54.9 (14 155) | 100.0 (2538) | 3.06*** (2.42, 3.87) | 2.66*** (1.66, 4.25) | 1.96*** (1.62, 2.38) | 1.56** (1.20, 2.02) | 1.35 (0.84, 2.13) |
| Mother smoked during pregnancy | ||||||||||
| Never (Ref) | 11.1 (366) | 2.4 (83) | 17.1 (650) | 69.5 (2572) | 100.0 (3671) | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| Any cigarettes/d | 23.0 (267) | 3.6 (44) | 22.8 (308) | 50.6 (737) | 100.0 (1356) | 2.85*** (2.27, 3.57) | 2.09** (1.32, 3.31) | 1.83*** (1.50, 2.23) | 1.56** (1.21, 2.00) | 1.14 (0.72, 1.82) |
| < 1 pack/d | 21.1 (175) | 3.8 (33) | 22.7 (223) | 52.5 (556) | 100.0 (987) | 2.52*** (1.96, 3.24) | 2.11** (1.28, 3.49) | 1.75*** (1.41, 2.19) | 1.44* (1.08, 1.91) | 1.20 (0.73, 1.00) |
| ≥1 pack/d | 27.2 (92) | 3.2 (11) | 23.1 (85) | 46.5 (181) | 100.0 (369) | 3.66*** (2.64, 5.07) | 2.02 (0.90, 4.52) | 2.02*** (1.44, 2.83) | 1.81** (1.23, 2.67) | 1.00 (0.44, 2.30) |
| Mother ever smoked by smoked during pregnancy | ||||||||||
| Never daily | 8.7 (202) | 1.8 (48) | 15.1 (385) | 74.4 (1854) | 100.0 (2489) | 0.46*** (0.34, 0.61) | 0.42** (0.24, 0.74) | 0.59*** (0.47, 0.74) | 0.77 (0.56, 1.06) | 0.72 (0.41, 1.27) |
| Ever daily, but did not smoke during pregnancy (Ref) | 15.5 (164) | 3.4 (35) | 20.8 (265) | 60.2 (718) | 100.0 (1182) | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| Ever daily and smoked during pregnancy any cigarettes/d | 23.0 (267) | 3.6 (44) | 22.8 (308) | 50.6 (737) | 100.0 (1356) | 1.76*** (1.33, 2.32) | 1.25 (0.72, 2.15) | 1.30* (1.03, 1.65) | 1.35 (0.99, 1.84) | 0.96 (0.55, 1.66) |
| Mother ever smoked by smoked during pregnancy | ||||||||||
| Ever daily and smoked during pregnancy < 1 pack/d | 21.1 (175) | 3.8 (33) | 22.7 (223) | 52.5 (556) | 100.0 (987) | 1.59** (1.16, 2.10) | 1.26 (0.71, 2.25) | 1.25 (0.97, 1.61) | 1.25 (0.89, 1.74) | 1.01 (0.56, 1.82) |
| Ever daily and smoked during pregnancy ≥ 1 packs/d | 27.2 (92) | 3.2 (11) | 23.1 (85) | 46.5 (181) | 100.0 (369) | 2.26*** (1.57, 3.26) | 1.21 (0.51, 2.84) | 1.44* (1.00, 2.06) | 1.58* (1.03, 2.41) | 0.84 (0.35, 2.03) |
| Mother's smoking history | ||||||||||
| Group 1: never daily (Ref) | 8.7 (202) | 1.8 (48) | 15.1 (385) | 74.4 (1854) | 100.0 (2489) | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| Group 2: quit daily before pregnancy | 12.0 (33) | 3.3 (9) | 10.6 (37) | 74.2 (224) | 100.0 (303) | 1.37 (0.85, 2.22) | 1.83 (0.73, 4.57) | 0.70 (0.45, 1.00) | 1.96* (1.11, 3.48) | 2.62* (1.04, 6.56) |
| Group 3: did not smoke during pregnancy, then relapse to daily | 18.3 (83) | 4.5 (17) | 24.2 (133) | 53.1 (284) | 100.0 (517) | 2.92*** (2.05, 4.17) | 3.49*** (1.80, 6.77) | 2.24*** (1.60, 2.93) | 1.31 (0.88, 1.94) | 1.56 (0.70, 3.07) |
| Group 4: did not smoke during pregnancy, relapsed, then quit daily | 15.5 (48) | 2.1 (9) | 27.0 (95) | 55.4 (210) | 100.0 (362) | 2.38*** (1.49, 3.80) | 1.55 (0.60, 3.97) | 2.40*** (1.72, 3.34) | 0.99 (0.61, 1.61) | 0.65 (0.24, 1.71) |
| Group 5: smoked during pregnancy any cigarettes/d, quit daily after pregnancy | 17.6 (42) | 3.9 (8) | 26.2 (70) | 52.3 (174) | 100.0 (294) | 2.87*** (1.78, 4.61) | 3.07* (1.22, 7.71) | 2.47*** (1.71, 3.56) | 1.16 (0.69, 1.97) | 1.25 (0.51, 3.03) |
| Group 6: smoked during pregnancy any cigarettes/d, continued daily after pregnancy | 24.5 (225) | 3.5 (36) | 21.8 (238) | 50.2 (563) | 100.0 (1062) | 4.16*** (3.18, 5.45) | 2.90*** (1.66, 5.06) | 2.14*** (1.68, 2.72) | 1.95*** (1.44, 2.63) | 1.36 (0.77, 2.30) |
Note. CI = confidence interval; NLSY79-CYA = Children and Young Adults of the National Longitudinal Survey of Youth 1979; UOR = unadjusted odds ratio. Youth smoking trajectories were characterized as early-onset, early-experiment, late-onset smoker or nonsmoker on the basis of a latent trajectory analysis fit to data on repeated assessments of smoking in the past 30 d by respondents aged 14–25 y observed between 1994–2006 in the NLSY79-CYA. UORs of smoking trajectories relative to the early-experiment smoking trajectory group are not shown because statistical inference is limited by sample power for this group. Frequencies 95% CIs, and tests of statistical significance have been adjusted for survey weights and clustering within families.
*P < .05; **P < .01; ***P < .001.