Distribution of maternal characteristics across preterm birth status*
| Variables | Overall (n=5297) | Preterm Birth (Gestational Age <37 weeks) n=356 | Term Birth (Gestational Age ≥37 weeks) n=4546 | χ2
p value | |||
| n (%) | 95% CI | n (%) | 95% CI | n (%) | 95% CI | ||
| Maternal age | 0.332 | ||||||
| <35yrs | 4117 (79.23) | 78.10 to 80.31 | 269 (77.08) | 72.36 to 81.19 | 3541 (79.27) | 78.05 to 80.43 | |
| ≥35yrs | 1079 (20.77) | 19.68 to 21.89 | 80 (22.92) | 18.80 to 27.63 | 926 (20.73) | 18.80 to 27.63 | |
| Marital status | 0.657 | ||||||
| Single/divorced/separated | 262 (5.06) | 4.49 to 5.69 | 17 (4.96) | 3.10 to 7.83 | 198 (4.44) | 3.87 to 5.09 | |
| Married/common-law | 4916 (94.94) | 94.30 to 95.50 | 326 (95.04) | 92.17 to 96.89 | 4260 (95.56) | 94.91 to 96.13 | |
| Ethnicity | 0.004 | ||||||
| White/Caucasian | 4085 (78.98) | 77.85 to 80.07 | 253 (73.76) | 68.83 to 78.15 | 3574 (80.28) | 79.08 to 81.42 | |
| Others | 1087 (21.02) | 19.93 to 22.15 | 90 (26.24) | 21.85 to 31.16 | 878 (19.72) | 18.58 to 20.92 | |
| Duration of stay in Canada | 0.061 | ||||||
| <5 years | 473 (9.26) | 8.49 to 10.08 | 39 (11.64) | 8.61 to 15.54 | 380 (8.63) | 7.84 to 9.25 | |
| Born/5 years+ | 4636 (90.74) | 89.91 to 91.51 | 296 (88.36) | 84.45 to 91.38 | 4022 (91.37) | 90.50 to 92.16 | |
| Body mass index | 0.001 | ||||||
| Underweight (<18.5 kg/m2) | 214 (4.33) | 3.80 to 4.94 | 12 (3.69) | 2.10 to 6.39 | 180 (4.23) | 3.66 to 4.87 | |
| Normal weight (18.5– 24.99) | 3084 (62.45) | 61.09 to 63.79 | 183 (56.31) | 50.85 to 61.62 | 2694 (63.28) | 61.82 to 64.72 | |
| Overweight (25–29.99 kg/m2) | 1066 (21.59) | 20.46 to 22.76 | 72 (22.15) | 17.69 to 27.00 | 924 (21.71) | 20.49 to 22.97 | |
| Obesity (≥30 kg/m2) | 574 (11.62) | 10.76 to 12.54 | 58 (17.85) | 14.05 to 22.40 | 459 (10.78) | 9.88 to 11.75 | |
| Parity | 0.004 | ||||||
| Primiparous | 2649 (51.27) | 49.90 to 52.63 | 201 (58.94) | 54.64 to 64.80 | 2266 (50.92) | 49.45 to 52.39 | |
| Multiparous | 2518 (48.73) | 47.37 to 50.09 | 140 (41.06) | 35.19 to 45.36 | 2184 (49.08) | 47.61 to 50.54 | |
| Intended pregnancy | 0.805 | ||||||
| Yes | 4175 (80.51) | 79.40 to 81.56 | 62 (18.02) | 14.30 to 22.45 | 829 (18.58) | 17.46 to 19.75 | |
| No | 1011 (19.49) | 18.44 to 20.60 | 282 (81.98) | 77.54 to 85.69 | 3633 (81.42) | 80.25 to 8253 | |
| Smoked before pregnancy | 0.062 | ||||||
| Yes | 1095 (21.13) | 20.04 to 22.26 | 259 (75.29) | 70.44 to 79.57 | 3547 (79.53) | 78.31 to 80.68 | |
| No | 4088 (78.87) | 77.74 to 79.96 | 85 (24.71) | 20.43 to 29.55 | 913 (20.47) | 19.31 to 21.68 | |
| Alcohol consumption before pregnancy | 0.531 | ||||||
| Yes | 4363 (84.13) | 83.11 to 85.10 | 49 (14.24) | 10.93 to 18.36 | 692 (15.51) | 14.47 to 16.60 | |
| No | 823 (15.87) | 14.90 to 16.89 | 295 (85.76) | 81.64 to 89.07 | 3770 (84.49) | 83.39 to 85.52 | |
| Drug abuse before pregnancy | 0.519 | ||||||
| Yes | 750 (14.48) | 13.54 to 15.46 | 290 (84.30) | 80.06 to 87.78 | 3814 (85.57) | 84.51 to 86.57 | |
| No | 4430 (85.52) | 84.53 to 86.45 | 54 (15.70) | 12.22 to 19.94 | 643 (14.43) | 13.42 to 15.49 | |
| Maternal education | 0.917 | ||||||
| Less than high school | 174 (3.37) | 2.91 to 3.90 | 11 (3.22) | 1.79 to 5.72 | 126 (2.84) | 2.39 to 3.37 | |
| Completed high school | 893 (17.31) | 16.29 to 18.36 | 56 (16.37) | 12.81 to 20.69 | 722 (16.25) | 15.19 to 17.36 | |
| More than high school | 4093 (79.32) | 78.19 to 80.40 | 275 (80.41) | 75.85 to 84.28 | 3595 (80.91) | 79.73 to 82.04 | |
| Household income | 0.436 | ||||||
| ≥$100 000 | 2659 (52.52) | 51.14 to 53.89 | 176 (52.54) | 47.17 to 57.84 | 2358 (53.98) | 52.50 to 55.45 | |
| $70 000 to <$100,000 | 1204 (23.78) | 22.63 to 24.97 | 74 (22.09) | 17.96 to 26.86 | 1059 (24.24) | 22.99 to 25.53 | |
| $40 000 to <$70,000 | 723 (14.28) | 13.34 to 15.27 | 51 (15.22) | 11.75 to 19.49 | 591 (13.53) | 12.55 to 14.57 | |
| <$40 000 | 477 (9.42) | 8.64 to 10.25 | 34 (10.15) | 7.33 to 13.88 | 360 (8.24) | 7.46 to 9.09 | |
| Social support anytime during pregnancy | 0.216 | ||||||
| Adequate | 4053 (77.93) | 76.78 to 79.03 | 263 (75.79) | 70.99 to 80.01 | 3514 (78.63) | 77.40 to 79.81 | |
| Inadequate | 1148 (22.07) | 20.96 to 23.22 | 84 (24.21) | 19.98 to 29.00 | 955 (21.37) | 20.19 to 22.59 | |
| Depression anytime during pregnancy | |||||||
| Yes | 1311 (25.14) | 23.98 to 26.33 | 96 (27.67) | 23.20 to 32.61 | 1086 (24.21) | 22.97 to 25.48 | 0.149 |
| No | 3904 (74.86) | 73.66 to 76.02 | 251 (72.33) | 67.38 to 76.94 | 3400 (75.79) | 74.51 to 77.02 | |
| Neighbourhood deprivation index | 0.002 | ||||||
| Quintile 1 (least deprived) | 1323 (27.08) | 25.85 to 28.35 | 93 (26.12) | 21.81 to 30.94 | 1176 (27.68) | 26.36 to 29.05 | |
| Quintile 2 | 1259 (25.77) | 24.56 to 27.01 | 76 (21.35) | 17.39 to 25.92 | 1119 (26.34) | 25.04 to 27.69 | |
| Quintile 3 | 972 (19.90) | 18.80 to 21.04 | 71 (19.94) | 16.10 to 24.43 | 839 (19.75) | 18.58 to 20.97 | |
| Quintile 4 | 736 (15.07) | 14.09 to 16.09 | 52 (14.61) | 11.30 to 18.67 | 639 (15.04) | 13.99 to 16.15 | |
| Quintile 5 (most deprived) | 595 (12.18) | 11.29 to 13.14 | 64 (17.98) | 14.32 to 22.32 | 475 (11.18) | 10.27 to 12.16 | |
| Neighbourhood median personal income | 0.054 | ||||||
| Quintile 1 (least deprived) | 1549 (31.05) | 29.78 to 32.35 | 106 (29.78) | 25.24 to 34.74 | 1369 (31.49) | 30.12 to 32.89 | |
| Quintile 2 | 1403 (28.13) | 26.89 to 29.39 | 96 (26.97) | 22.60 to 31.82 | 1229 (28.27) | 26.95 to 29.63 | |
| Quintile 3 | 881 (17.66) | 16.62 to 18.74 | 57 (16.01) | 12.55 to 20.20 | 776 (17.85) | 16.74 to 19.01 | |
| Quintile 4 | 666 (13.35) | 12.43 to 14.32 | 47 (13.20) | 10.06 to 17.14 | 574 (13.20) | 12.22 to 14.24 | |
| Quintile 5 (most deprived) | 489 (9.80) | 9.00 to 10.66 | 50 (14.04) | 10.80 to 18.06 | 399 (9.18) | 8.35 to 10.07 | |
*Sample size between variables differs as missing values were deleted using variable wise or pair-wise deletion approach.