Background
Methods
Study population
Outcomes
Determinants
Covariates
Variable | Definition |
---|---|
Low-income-cut-off (LICO) [16] | A measure of the income threshold below which a family will likely spend 20 percentage points more than the average family on food, shelter and clothing |
Medical condition prior to pregnancy | Yes in response to the question “Prior to your pregnancy, did you develop any medical conditions or health problems that required you to take medication for more than 2 weeks, have special care, or extra tests during pregnancy?” |
Medical condition during pregnancy | Yes in response to the question “During your pregnancy, did you develop any new medical conditions or health problems that required you to take medication for more than 2 weeks, have special care, or extra tests?” |
Depression prior to pregnancy | Yes in response to the question “Before your pregnancy, had you ever been prescribed anti-depressants or been diagnosed with depression? |
Short stature | Height of less than 1.55 metres (5 feet 2 inches) |
Statistical analysis
Results
All women (n = 71,200) | Primigravidas (n = 24,000) | Multigravidas | |||
---|---|---|---|---|---|
Previous PTB (n = 4,000) | No previous PTB | ||||
Previous early pregnancy lossa(n = 21,300) | No previous early pregnancy loss (n = 21,600) | ||||
Percent of sample | 33.8 | 5.7 | 30.0 | 30.5 | |
Determinants
| |||||
Prepregnancy BMI | |||||
<18.5 | 6.0 | 7.1 | 6.2 | 5.3 | 5.4 |
18.5-24.9 | 59.7 | 63.3 | 51.3 | 58.1 | 58.4 |
25.0-29.9 | 20.9 | 17.6 | 22.9 | 23.1 | 22.3 |
≥30 | 13.5 | 12.0 | 19.6 | 13.5 | 13.9 |
Gestational weight gain | |||||
<recommended | 18.6 | 16.6 | 18.0 | 19.4 | 20.2 |
=recommended | 23.0 | 22.1 | 23.2 | 22.3 | 24.9 |
>recommended | 59.4 | 61.3 | 58.7 | 58.3 | 54.9 |
Smoked 3rd trimester | 10.4 | 7.7 | 17.2 | 13.7 | 10.0 |
Covariates
| |||||
Maternal age | |||||
≤24 | 15.3 | 23.6 | 11.9 | 12.4 | 9.5 |
25-29 | 34.1 | 40.4 | 27.7 | 29.0 | 33.5 |
30-34 | 33.4 | 26.1 | 37.7 | 35.4 | 37.8 |
≥35 | 17.5 | 9.8 | 22.7 | 23.2 | 19.3 |
Maternal education | |||||
Less than high school | 6.8 | 5.1 | 12.4 | 7.8 | 6.7 |
High school graduate | 19.4 | 17.7 | 22.7 | 20.3 | 19.8 |
Post-secondary diploma | 37.7 | 38.1 | 41.6 | 36.8 | 37.4 |
University graduate | 36.1 | 39.2 | 23.3 | 35.2 | 36.1 |
Low-income-cut-off (LICO) | |||||
≤LICO | 18.0 | 14.9 | 26.2 | 19.1 | 19.1 |
>LICO | 74.0 | 75.3 | 69.1 | 74.1 | 74.0 |
Missing | 8.0 | 9.8 | 4.7 | 6.9 | 6.9 |
Short stature | 6.4 | 5.6 | 6.8 | 5.8 | 7.7 |
World region of birth | |||||
Canada | 76.7 | 77.8 | 82.2 | 76.4 | 74.9 |
Europe/Western nations | 6.0 | 5.8 | 4.4 | 6.4 | 5.9 |
Africa/Caribbean | 2.3 | 2.2 | 3.4 | 2.6 | 1.9 |
Middle East/North Africa | 2.6 | 2.6 | 2.3 | 1.9 | 3.3 |
Latin America | 2.3 | 1.8 | 1.3 | 2.2 | 3.2 |
East Asia/South East Asia/Pacific Islands | 5.7 | 5.4 | 3.0 | 6.4 | 5.7 |
South Asia | 4.5 | 4.5 | 3.5 | 4.1 | 5.1 |
Medical conditions prior to pregnancy | 15.2 | 14.3 | 20.5 | 16.6 | 13.8 |
Medical conditions during pregnancy | 24.4 | 24.8 | 32.2 | 25.1 | 21.8 |
Depression prior to pregnancy | 15.5 | 13.8 | 20.2 | 17.3 | 14.6 |
Perceived stress during pregnancy | |||||
Not stressful | 43.1 | 46.4 | 34.2 | 41.6 | 42.6 |
Somewhat stressful | 44.9 | 44.7 | 47.6 | 44.7 | 45.0 |
Very stressful | 12.0 | 8.9 | 18.2 | 13.8 | 12.4 |
No support during pregnancy | 12.8 | 10.0 | 16.8 | 14.7 | 13.3 |
Associations between adverse neonatal outcomes and BMI and GWG
PTB | SGA | LGA | ||||
---|---|---|---|---|---|---|
% | aOR (95% CI) | % | aOR (95% CI) | % | aOR (95% CI) | |
All women (n = 71,200) | 6.1 | 8.1 | 11.3 | |||
Prepregnancy BMI | ||||||
<18.5 | 8.4 | 1.55 [0.96 , 2.52] | 20.5 |
2.04 [1.46, 2.84]
| 4.3 | 0.64 [0.33, 1.20] |
18.5-24.9 | 5.6 | Reference | 10.0 | Reference | 7.5 | Reference |
25.0-29.9 | 6.1 | 0.98 [0.72, 1.33] | 8.2 | 0.95 [0.74, 1.22] | 11.4 |
1.38 [1.08, 1.75]
|
≥30 | 7.4 | 1.02 [0.73,1.42] | 8.6 | 0.86 [0.63, 1.15] | 14.1 |
1.89 [1.45, 2.47]
|
Gestational weight gain | ||||||
< recommended | 6.5 | 1.35 [0.92, 1.97] | 16.1 |
1.56 [1.20, 2.03]
| 4.6 | 0.57 [0.39, 0.84] |
= recommended | 4.5 | Reference | 10.9 | Reference | 7.7 | Reference |
> recommended | 6.7 |
1.45 [1.06, 1.98]
| 7.7 | 0.70 [0.56, 0.87] | 11.0 |
1.34 [1.04, 1.72]
|
Smoked 3rd trimester | ||||||
Yes | 8.9 | 1.31 [0.92, 1.86] | 18.4 |
2.06 [1.59, 2.67]
| 2.8 | 0.26 [0.16, 0.43] |
No | 5.8 | Reference | 9.1 | Reference | 9.7 | Reference |
Primigravidas (n = 24,000) | 6.8 | 10.5 | 7.5 | |||
Prepregnancy BMI | ||||||
<18.5 | 8.7 | 1.63 [0.77, 3.47] | 28.3 |
2.47 [1.53, 3.99]
| 0.8 | 0.14 [0.005, 4.69] |
81.5-24.9 | 6.1 | Reference | 12.2 | Reference | 6.1 | Reference |
25.0-29.9 | 8.6 | 1.30 [0.80, 2.12] | 10.4 | 0.89 [0.59, 1.34] | 7.5 | 1.12 [0.67, 1.87] |
≥30 | 6.6 | 0.86 [0.45, 1.66] | 12.1 | 0.97 [0.61, 1.57] | 11.4 |
1.89 [1.11, 3.21]
|
Gestational weight gain | ||||||
< recommended | 6.6 | 1.60 [0.78, 3.29] | 20.8 | 1.40 [0.92, 2.12] | 2.1 | 0.49 [0.17, 1.41] |
= recommended | 3.9 | Reference | 15.9 | Reference | 4.1 | Reference |
> recommended | 7.9 |
2.02 [1.13, 3.63]
| 9.9 | 0.61 [0.44, 0.86] | 8.8 |
2.01 [1.12, 3.61]
|
Smoked 3rd trimester | ||||||
Yes | 8.2 | 1.04 [0.53, 2.04] | 27.4 |
2.32 [1.49, 3.62]
| 2.1 | 0.29 [0.08, 1.13] |
No | 6.7 | Reference | 11.8 | Reference | 7.0 | Reference |
Multigravidas, previous PTB (n = 4,000) | 13.3 | 7.4 | 10.9 | |||
Prepregnancy BMI | ||||||
<18.5 | 8.6 | 0.70 [0.05, 9.26] | 19.7 | 1.79 [0.20, 15.69] | 0 | --b |
18.5-24.9 | 15.0 | Reference | 9.3 | Reference | 7.2 | Reference |
25.0-29.9 | 9.5 | 0.56 [0.19, 1.67] | 6.8 | 1.14 [0.26, 4.92] | 10.6 | 1.58 [0.33, 7.49] |
≥30 | 14.9 | 0.89 [0.36, 2.22] | 5.9 | 0.42 [0.08, 2.18] | 3.8 | 0.55 [0.07, 4.34] |
Gestational weight gain | ||||||
< recommended | 13.1 | 0.83 [0.22, 3.10] | 17.1 | 1.40 [0.35, 5.58] | 6.9 | 1.24 [0.08, 18.45] |
= recommended | 15.6 | Reference | 12.8 | Reference | 4.6 | Reference |
> recommended | 12.5 | 0.93 [0.33, 2.59] | 4.5 | 0.30 [0.08, 1.14] | 7.7 | 1.01 [0.14, 7.45] |
Smoked 3rd trimester | ||||||
Yes | 16.0 | 1.45 [0.46, 4.61] | 12.8 | 1.77 [0.43, 7.24] | 0 | --b |
No | 12.8 | Reference | 7.8 | Reference | 8.3 | Reference |
Multigravidas, no previous PTB, previous lossa (n = 21,300) | 6.2 | 7.1 | 11.8 | |||
Prepregnancy BMI | ||||||
<18.5 | 10.3 | 1.90 [0.73, 4.93] | 14.2 | 1.75 [0.84, 3.66] | 6.7 | 1.04 [0.37, 2.90] |
18.5-24.9 | 5.7 | Reference | 9.2 | Reference | 7.5 | Reference |
25.0-29.9 | 5.9 | 1.00 [0.57, 1.75] | 6.4 | 0.72 [0.44, 1.19] | 12.3 | 1.53 [1.00, 2.36] |
≥30 | 7.2 | 0.92 [0.47, 1.80] | 8.3 | 0.84 [0.46, 1.54] | 16.9 |
2.61 [1.61, 4.23]
|
Gestational weight gain | ||||||
< recommended | 8.1 | 1.14 [0.59, 2.19] | 14.2 | 1.65 [0.96, 2.83] | 5.0 | 0.41 [0.20, 0.81] |
= recommended | 5.9 | Reference | 8.2 | Reference | 9.9 | Reference |
> recommended | 5.7 | 0.93 [0.53, 1.62] | 7.1 | 0.83 [0.50, 1.36] | 11.4 | 1.02 [0.64, 1.63] |
Smoked 3rd trimester | ||||||
Yes | 8.8 | 1.77 [0.97, 3.23] | 16.3 |
2.26 [1.40, 3.64]
| 10.8 | 0.23 [0.10, 0.51] |
No | 5.8 | Reference | 7.5 | Reference | 3.6 | Reference |
Multigravidas, no previous PTB, no previous lossa (n = 21,600) | 4.0 | 6.7 | 14.9 | |||
Prepregnancy BMI | ||||||
<18.5 | 6.1 | 2.14 [0.56, 8.20] | 15.3 | 1.81 [0.84, 3.88] | 6.9 | 0.93 [0.31, 2.76] |
18.5-24.9 | 3.5 | Reference | 8.1 | Reference | 9.3 | Reference |
25.0-29.9 | 3.3 | 0.75 [0.37, 1.51] | 8.3 | 1.24 [0.76, 2.03] | 14.2 | 1.46 [0.99, 2.14] |
≥30 | 6.5 | 1.21 [0.59, 2.50] | 6.2 | 0.78 [0.38, 1.61] | 16.8 |
1.79 [1.14, 2.80]
|
Gestational weight gain | ||||||
< recommended | 3.8 | 1.98 [0.71, 5.51] | 13.6 |
1.76 [1.03, 3.03]
| 6.2 | 0.66 [0.34, 1.26] |
= recommended | 2.1 | Reference | 8.2 | Reference | 9.9 | Reference |
> recommended | 4.9 | 2.52 [0.99, 6.37] | 6.4 | 0.80 [0.49, 1.30] | 13.8 | 1.36 [0.88, 2.08] |
Smoked 3rd trimester | ||||||
Yes | 7.0 | 1.13 [0.50, 2.59] | 15.2 |
1.92 [1.10, 3.35]
| 3.3 | 0.29 [0.12, 0.71] |
No | 3.7 | Reference | 7.6 | Reference | 12.1 | Reference |
Preterm birth
Small-for-gestational-age
Large-for-gestational-age
PAFs for adverse neonatal outcomes
PAF (%, 95 CI) | ||||
---|---|---|---|---|
Characteristic | Prevalence (%) of characteristic | PTB | SGA | LGA |
All women (n = 71,200) | ||||
Underweight | 6.0 | 2.6 [2.5, 2.7] | 5.3 [5.2, 5.4] | −1.4 [-1.4, -1.3] |
Overweight | 20.9 | −0.4 [-0.6, -0.2] | −0.8 [-0.9, -0.7] | 6.5 [6.3, 6.6] |
Obese | 13.5 | 0.3 [0.1, 0.4] | −1.6 [-1.7, -1.5] | 8.9 [8.8, 9.1] |
< recommended GWG | 18.6 | 4.7 [4.4, 5.0] | 9.2 [9.0, 9.4] | −6.3 [-6.4, -6.2] |
> recommended GWG | 59.4 | 18.2 [17.8, 18.7] | −16.3 [-16.4, -16.1] | 15.9 [15.4, 16.3] |
Smoked 3rd trimester | 10.4 | 3.2 [3.0, 3.3] | 8.7 [8.6, 8.8] | −7.1 [-7.2, -7.0] |
Primigravidas (n = 24,000) | ||||
Underweight | 7.1 | 3.3 [3.1, 3.5] | 7.5 [7.4, 7.7] | −4.6 [-4.7, -4.5] |
Overweight | 17.6 | 4.8 [4.5, 5.1] | −1.4 [-1.6, -1.3] | 2.0 [1.7, 2.2] |
Obese | 12.0 | −1.7 [-2.0, -1.5] | −0.1 [-0.2, 0.1] | 8.9 [8.6, 9.1] |
< recommended GWG | 16.6 | 5.7 [5.5, 6.0] | 6.1 [5.8, 6.5] | −5.1 [-5.3, -4.9] |
> recommended GWG | 61.3 | 33.9 [33.1, 34.6] | −22.8 [-23.4, -22.3] | 37.9 [37.1, 38.6] |
Smoked 3rd trimester | 7.7 | 0.3 [0.1, 0.5] | 7.5 [7.4, 7.6] | −5.1 [-5.2, -5.0] |
Multigravidas, previous PTB (n = 4,000) | ||||
Underweight | 6.2 | −1.4 [-1.6 ,-1.2] | 4.6 [4.2, 5.1] | --a |
Overweight | 22.9 | −10.5 [-11.1, -9.9] | 1.9 [1.3, 2.5] | --a |
Obese | 19.6 | −2.1 [-2.6, -1.7] | −14.0 [-14.9,-13.2] | --a |
< recommended GWG | 18.0 | −3.0 [-3.6, -2.4] | 8.0 [7.1, 8.9] | --a |
> recommended GWG | 58.7 | −3.6 [-5.1, -2.1] | −54.8 [-57.1, -52.4] | --a |
Smoked in 3rd trimester | 17.2 | 5.4 [4.9, 6.0] | 9.7 [9.0, 10.4] | --a |
Multigravidas, no previous PTB, previous loss
b
(n = 21,300) | ||||
Underweight | 5.3 | 3.5 [3.3, 3.7] | 3.2 [3.1, 3.4] | 0.1 [0.0, 0.2] |
Overweight | 23.1 | −0.05 [-0.4, 0.3] | −5.6 [-5.9, -5.4] | 8.9 [8.6, 9.2] |
Obese | 13.5 | −1.2 [-1.4, -0.9] | −2.2 [-2.4, -2.0] | 13.0 [12.7, 13.2] |
< recommended GWG | 19.4 | 2.7 [2.3, 3.1] | 11.0 [10.6, 11.4] | −11.4 [-11.6, -11.1] |
> recommended GWG | 58.3 | −3.7 [-4.5, -2.8] | −8.6 [-9.3, -7.9] | 1.1 [0.2, 1.9] |
Smoked 3rd trimester | 13.7 | 8.0 [7.7, 8.2] | 13.0 [12.7, 13.2] | −13.2 [-13.4,-13.0] |
Multigravidas, no previous PTB, no previous loss
b
(n = 21,600) | ||||
Underweight | 5.4 | 4.2 [4.0, 4.5] | 3.8 [3.7, 4.0] | −0.2 [-0.3, -0.1] |
Overweight | 22.3 | −5.9 [-6.4, -5.5] | 3.9 [3.6, 4.2] | 7.6 [7.4, 7.8] |
Obese | 13.9 | 3.4 [3.0, 3.8] | −2.5 [-2.7, -2.3] | 7.9 [7.7, 8.1] |
< recommended GWG | 20.2 | 9.5 [9.1, 9.9] | 12.3 [11.6, 13.1] | −5.0 [-5.2, -4.8] |
> recommended GWG | 54.9 | 38.7 [37.8, 39.5] | −9.3 [-10.0, -8.6] | 15.2 [14.6, 15.8] |
Smoked 3rd trimester | 9.0 | 1.6 [1.2, 1.9] | 7.0 [6.8, 7.2] | −5.4 [-5.4, -5.3] |