Table. Multivariable Regression Results for Smoking Cessation at Various Points in Pregnancy and Preterm Birtha.
| Covariate | Adjusted Odds Ratio (95% CI) | |||||
|---|---|---|---|---|---|---|
| Cessation Throughout Pregnancy (n = 2 542 018)b | Cessation After Trimester 1 (n = 2 538 338)c | Cessation After Trimester 2 (n = 1 596 099)d | Cessation in Trimester 3 (n = 2 538 338)c | Preterm Birth Among Prepregnancy Smokers (n = 2 537 393)e | Preterm Birth Among Prepregnancy and Pregnancy Nonsmokers (n = 21 344 623)f | |
| Year of delivery (reference, 2011) | ||||||
| 2012 | 1.02 (1.01-1.03) | 0.99 (0.98-1.01) | 1.02 (0.99-1.04) | 1.02 (1.00-1.04) | 0.98 (0.97-1.00) | 0.99 (0.98-0.99) |
| 2013 | 1.02 (1.00-1.03) | 0.99 (0.97-1.00) | 1.03 (1.01-1.06) | 1.03 (1.01-1.06) | 0.99 (0.98-1.00) | 0.97 (0.96-0.97) |
| 2014 | 1.01 (1.00-1.02) | 1.03 (1.01-1.04) | 1.05 (1.02-1.07) | 1.06 (1.04-1.08) | 1.00 (0.99-1.02) | 0.97 (0.96-0.97) |
| 2015 | 1.05 (1.03-1.06) | 1.06 (1.04-1.08) | 1.06 (1.03-1.08) | 1.07 (1.05-1.10) | 1.01 (0.99-1.02) | 0.97 (0.96-0.97) |
| 2016 | 1.07 (1.06-1.08) | 1.07 (1.05-1.09) | 1.08 (1.05-1.10) | 1.09 (1.07-1.11) | 1.03 (1.01-1.04) | 0.98 (0.97-0.98) |
| 2017 | 1.05 (1.04-1.06) | 1.04 (1.02-1.06) | 1.08 (1.05-1.11) | 1.08 (1.06-1.11) | 1.07 (1.05-1.08) | 1.03 (1.03-1.04) |
| Age at delivery (reference, 25-29), y | ||||||
| <15 | 1.22 (1.00-1.49) | 2.19 (1.74-2.74) | 2.10 (1.49-2.95) | 1.79 (1.29-2.47) | 1.41 (1.13-1.76) | 1.76 (1.70-1.83) |
| 15-19 | 1.16 (1.15-1.18) | 1.36 (1.34-1.38) | 1.31 (1.28-1.35) | 1.18 (1.16-1.21) | 1.00 (0.98-1.01) | 1.14 (1.13-1.15) |
| 20-24 | 1.02 (1.01-1.02) | 1.09 (1.08-1.10) | 1.13 (1.11-1.15) | 1.07 (1.06-1.09) | 0.96 (0.95-0.97) | 1.02 (1.02-1.03) |
| 30-34 | 1.01 (1.00-1.02) | 0.96 (0.95-0.97) | 0.95 (0.93-0.97) | 0.98 (0.96-0.99) | 1.14 (1.13-1.16) | 1.05 (1.05-1.06) |
| 35-39 | 0.95 (0.94-0.96) | 0.93 (0.92-0.95) | 0.94 (0.92-0.97) | 0.97 (0.95-0.99) | 1.38 (1.36-1.40) | 1.23 (1.22-1.23) |
| 40-44 | 0.84 (0.82-0.87) | 0.88 (0.85-0.92) | 0.96 (0.91-1.02) | 0.96 (0.91-1.00) | 1.65 (1.61-1.70) | 1.51 (1.49-1.52) |
| 45-49 | 0.81 (0.70-0.94) | 0.89 (0.73-1.08) | 0.90 (0.67-1.22) | 0.96 (0.74-1.23) | 1.76 (1.54-2.01) | 1.77 (1.73-1.82) |
| 50-54 | 0.55 (0.24-1.27) | 0.99 (0.38-2.56) | 0.52 (0.07-3.85) | 0.77 (0.19-3.15) | 1.60 (0.80-3.22) | 2.05 (1.88-2.22) |
| Race/ethnicity (reference, non-Hispanic white) | ||||||
| Hispanic | 2.35 (2.32-2.38) | 2.15 (2.12-2.19) | 1.65 (1.61-1.69) | 1.70 (1.67-1.74) | 1.08 (1.06-1.10) | 1.12 (1.12-1.13) |
| Non-Hispanic black | 1.44 (1.42-1.45) | 1.51 (1.49-1.53) | 1.44 (1.41-1.47) | 1.37 (1.35-1.40) | 1.53 (1.51-1.54) | 1.60 (1.59-1.60) |
| Non-Hispanic other | 1.28 (1.26-1.29) | 1.41 (1.39-1.44) | 1.34 (1.31-1.38) | 1.28 (1.25-1.31) | 1.13 (1.11-1.15) | 1.11 (1.10-1.11) |
| Unknown | 1.28 (1.20-1.35) | 1.06 (0.98-1.16) | 1.21 (1.07-1.36) | 1.09 (0.98-1.21) | 1.19 (1.11-1.27) | 1.12 (1.10-1.15) |
| Educational attainment (reference, <high school) | ||||||
| High school graduate | 1.51 (1.49-1.52) | 1.45 (1.43-1.47) | 1.26 (1.24-1.28) | 1.26 (1.24-1.28) | 0.88 (0.87-0.89) | 0.93 (0.93-0.94) |
| At least some college | 2.35 (2.33-2.38) | 2.13 (2.10-2.16) | 1.59 (1.56-1.62) | 1.60 (1.57-1.63) | 0.82 (0.81-0.83) | 0.80 (0.80-0.80) |
| Marital status (reference, unmarried) | 1.48 (1.47-1.49) | 1.11 (1.10-1.12) | 0.99 (0.98-1.01) | 1.03 (1.02-1.05) | 0.90 (0.89-0.91) | 0.81 (0.80-0.81) |
| WIC benefits (reference, none) | 0.79 (0.79-0.80) | 0.87 (0.86-0.88) | 0.90 (0.89-0.91) | 0.88 (0.87-0.89) | 0.80 (0.80-0.81) | 0.92 (0.91-0.92) |
| Source of payment (reference, private insurance) | ||||||
| Medicaid | 0.57 (0.57-0.58) | 0.66 (0.66-0.67) | 0.86 (0.85-0.88) | 0.80 (0.79-0.81) | 1.20 (1.19-1.21) | 1.13 (1.13-1.13) |
| Other | 0.80 (0.79-0.81) | 0.91 (0.89-0.93) | 1.09 (1.05-1.13) | 1.01 (0.99-1.04) | 1.15 (1.13-1.18) | 1.10 (1.09-1.10) |
| Self-pay | 0.49 (0.48-0.50) | 0.56 (0.54-0.58) | 0.84 (0.81-0.88) | 0.76 (0.73-0.79) | 1.61 (1.57-1.65) | 0.96 (0.95-0.97) |
| Gravida (reference, 1) | ||||||
| 2 | 0.89 (0.88-0.90) | 0.88 (0.86-0.90) | 0.95 (0.92-0.98) | 0.94 (0.91-0.96) | 1.08 (1.06-1.10) | 1.06 (1.06-1.07) |
| 3 | 0.84 (0.82-0.86) | 0.84 (0.82-0.87) | 0.92 (0.88-0.96) | 0.91 (0.88-0.95) | 1.14 (1.11-1.16) | 1.10 (1.08-1.11) |
| 4 | 0.79 (0.76-0.82) | 0.81 (0.77-0.84) | 0.95 (0.89-1.01) | 0.93 (0.88-0.98) | 1.20 (1.17-1.24) | 1.13 (1.12-1.15) |
| Para (reference, 1) | ||||||
| 2 | 0.69 (0.68-0.70) | 0.68 (0.67-0.69) | 0.77 (0.75-0.79) | 0.77 (0.75-0.79) | 0.90 (0.89-0.92) | 0.86 (0.85-0.86) |
| 3 | 0.55 (0.54-0.57) | 0.58 (0.56-0.60) | 0.71 (0.68-0.74) | 0.69 (0.66-0.72) | 0.94 (0.92-0.96) | 0.89 (0.88-0.90) |
| 4 | 0.40 (0.39-0.41) | 0.46 (0.45-0.48) | 0.63 (0.60-0.66) | 0.59 (0.56-0.62) | 1.08 (1.05-1.11) | 1.00 (0.98-1.01) |
| Abortus (reference, 0) | ||||||
| 1 | 1.01 (0.99-1.02) | 1.05 (1.03-1.07) | 1.05 (1.02-1.07) | 1.03 (1.01-1.05) | 0.98 (0.97-0.99) | 1.01 (1.01-1.02) |
| 2 | 0.97 (0.95-0.98) | 1.04 (1.01-1.06) | 1.04 (1.01-1.08) | 1.01 (0.98-1.05) | 1.01 (0.99-1.02) | 1.09 (1.08-1.10) |
| 3 | 0.91 (0.88-0.93) | 1.02 (0.98-1.05) | 1.00 (0.95-1.05) | 0.98 (0.93-1.02) | 1.05 (1.03-1.08) | 1.18 (1.17-1.20) |
| 4 | 0.80 (0.78-0.83) | 0.90 (0.87-0.94) | 1.01 (0.96-1.06) | 0.95 (0.91-1.00) | 1.12 (1.09-1.16) | 1.30 (1.28-1.31) |
| Plurality (reference, 1) | ||||||
| 2 | NA | NA | NA | NA | 10.80 (10.64-10.97) | 13.25 (13.18-13.31) |
| ≥3 | NA | NA | NA | NA | 156.78 (123.24-199.45) | 165.78 (157.52-174.46) |
| Smoking frequency, No. of cigarettes/d (reference, 1-9) | ||||||
| 3 mo prior to pregnancy | ||||||
| 10-19 | 0.49 (0.49-0.49) | 1.30 (1.28-1.31) | 1.65 (1.61-1.68) | 1.23 (1.21-1.25) | 0.95 (0.94-0.96) | NA |
| ≥20 | 0.31 (0.31-0.32) | 1.06 (1.05-1.08) | 1.68 (1.64-1.71) | 1.11 (1.09-1.12) | 0.91 (0.90-0.93) | NA |
| Trimester 1 | ||||||
| 10-19 | NA | 0.38 (0.37-0.38) | 1.12 (1.10-1.15) | NA | NA | NA |
| ≥20 | NA | 0.39 (0.38-0.39) | 1.53 (1.49-1.58) | NA | NA | NA |
| Trimester 2 | ||||||
| 10-19 | NA | NA | 0.23 (0.23-0.24) | NA | NA | NA |
| ≥20 | NA | NA | 0.19 (0.18-0.19) | NA | NA | NA |
| Smoking frequency, No. of cigarettes/d (reference, 0) | ||||||
| Trimester 1 | ||||||
| 1-9 | NA | NA | 0.41 (0.40-0.42) | 1.16 (1.14-1.17) | NA | |
| 10-19 | NA | NA | 0.49 (0.47-0.50) | 1.24 (1.22-1.26) | NA | |
| ≥20 | NA | NA | 0.62 (0.60-0.64) | 1.30 (1.28-1.33) | NA | |
| Trimester 2 | ||||||
| 1-9 | NA | NA | 0.01 (0.01-0.01) | 1.42 (1.39-1.44) | NA | |
| 10-19 | NA | NA | 0.00 (0.00-0.00) | 1.50 (1.46-1.53) | NA | |
| ≥20 | NA | NA | 0.00 (0.00-0.00) | 1.58 (1.53-1.63) | NA | |
| Trimester 3 | ||||||
| 1-9 | NA | NA | NA | 0.78 (0.77-0.80) | NA | |
| 10-19 | NA | NA | NA | 0.78 (0.76-0.80) | NA | |
| ≥20 | NA | NA | NA | 0.79 (0.77-0.81) | NA | |
Abbreviation: NA, not applicable; WIC, Special Supplemental Nutrition Program for Women, Infants, and Children.
b
Total of 91 289 observations deleted from regression because missing value on at least 1 covariate (3.5%).
c
Total of 94 969 observations deleted from regression because missing value on at least 1 covariate (3.6%).
d
Total of 53 801 observations deleted from regression because missing value on at least 1 covariate (3.3%).
e
Total of 95 914 observations deleted from regression because missing value on at least 1 covariate (3.6%).
f
Total of 1 218 326 observations deleted from regression because missing value on at least 1 covariate (5.4%).