Table 2.
Sample Sizes, Characteristics, and Missingness of Data Among Pregnant Women, by Survey Cycle: NHANES, 1999 to 2014
| Variable | Survey Cycle | |||||||
|---|---|---|---|---|---|---|---|---|
| 1999–2000 | 2001–2002 | 2003–2004 | 2005–2006 | 2007–2008 | 2009–2010 | 2011–2012 | 2013–2014 | |
| N | 218 | 233 | 187 | 289 | 46 | 46 | 38 | 60 |
| Demographic characteristics | ||||||||
| Age, y | 27.5 (4.9) | 27.8 (5.1) | 28.4 (5.0) | 27.3 (4.6) | 26.9 (5.1) | 29.2 (6.8) | 29.4 (6.1) | 27.2 (5.6) |
| Race/ethnicity | ||||||||
| White (non‐Hispanic) | 101 (46.3) | 116 (49.8) | 96 (51.3) | 136 (47.1) | 9 (19.6) | 16 (34.8) | 11 (28.9) | 21 (35.0) |
| Black (non‐Hispanic) | 19 (8.7) | 25 (10.7) | 30 (16.0) | 34 (11.8) | 8 (17.4) | 5 (10.9) | 10 (26.3) | 17 (28.3) |
| Mexican | 65 (29.8) | 59 (25.3) | 47 (25.1) | 93 (32.2) | 19 (41.3) | 14 (30.4) | 5 (13.2) | 4 (6.7) |
| Other Hispanic | 18 (8.3) | 14 (6.0) | 5 (2.7) | 12 (4.2) | 7 (15.2) | 3 (6.5) | 4 (10.5) | 7 (11.7) |
| Non‐Hispanic Asian | ··· | ··· | ··· | ··· | ··· | ··· | 7 (18.4) | 7 (11.7) |
| Other race | 15 (6.9) | 19 (8.2) | 9 (4.8) | 14 (4.8) | 3 (6.5) | 8 (17.4) | 1 (2.6) | 4 (6.7) |
| Education | ||||||||
| Less than high school | 58 (28.4) | 60 (26.8) | 48 (26.1) | 80 (29.0) | 18 (39.1) | 11 (23.9) | 6 (16.7) | 9 (15.3) |
| High school graduate | 42 (20.6) | 44 (19.6) | 41 (22.3) | 55 (19.9) | 9 (19.6) | 9 (19.6) | 7 (19.4) | 15 (25.4) |
| Greater than high school | 104 (51.0) | 120 (53.6) | 95 (51.6) | 141 (51.1) | 19 (41.3) | 26 (56.5) | 23 (63.9) | 35 (59.3) |
| Family income/poverty ratio | ||||||||
| ≤1.30 | 52 (28.0) | 65 (29.1) | 62 (33.5) | 91 (33.1) | 15 (37.5) | 14 (36.8) | 10 (27.0) | 26 (46.4) |
| 1.30–≤1.85 | 22 (11.8) | 27 (12.1) | 23 (12.4) | 34 (12.4) | 7 (17.5) | 7 (18.4) | 6 (16.2) | 7 (12.5) |
| >1.85 | 112 (60.2) | 131 (58.7) | 100 (54.1) | 150 (54.5) | 18 (45.0) | 17 (44.7) | 21 (56.8) | 23 (41.1) |
| No. (proportion) with missing data | ||||||||
| Diet | 7 (3.2) | 2 (0.9) | 5 (2.7) | 5 (1.7) | 1 (2.2) | 0 | 2 (5.3) | 3 (5.0) |
| Physical activity | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Smoking status | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| BMI | 0 | 1 (0.4) | 1 (0.5) | 1 (0.3) | 0 | 0 | 0 | ···a |
| Blood pressure | 18 (8.3) | 12 (5.2) | 20 (10.7) | 14 (4.8) | 0 | 1 (2.2) | 5 (13.2) | 10 (16.7) |
| Total cholesterol | 14 (6.4) | 11 (4.7) | 15 (8.0) | 14 (4.8) | 5 (10.9) | 4 (8.7) | 3 (7.9) | 4 (6.7) |
| Fasting plasma glucose | 130 (59.6) | 136 (58.4) | 109 (58.3) | 158 (54.7) | 30 (65.2) | 28 (60.9) | 21 (55.3) | ···a |
| Missing despite morning examinationb | 17 (16.2) | 21 (17.8) | 14 (15.2) | 19 (12.7) | 4 (20.0) | 3 (14.3) | 2 (10.5) | ···a |
| Any CVH metric | 138 (63.3) | 141 (60.5) | 120 (64.2) | 167 (57.8) | 31 (67.4) | 28 (60.9) | 26 (68.4) | ···a |
| Missing despite morning examinationb | 25 (23.8) | 26 (22.0) | 25 (27.2) | 28 (18.7) | 5 (25.0) | 3 (14.3) | 7 (36.8) | ···a |
Data shown are for the sample (ie, survey weights not used). Mean (SD) is shown for continuous variables, and number (proportion) is shown for categorical variables. BMI and fasting plasma glucose data were only assessed in participants during survey years 1999 to 2012, as month of pregnancy information (needed for their assessment) was not available in 2013 to 2014. BMI indicates body mass index; CVH, cardiovascular health; NHANES, National Health and Nutrition Examination Survey.
BMI and fasting plasma glucose were measured in 2013 to 2014, but they are not used in the present analyses because month of pregnancy was not reported in 2013 to 2014 and is needed for classification of those metrics.
Only morning examination participants were eligible for fasting plasma glucose measurement; morning examination samples are designed with separate weights to be nationally representative. The number (proportion) listed herein indicate the number missing the measurement despite attending a morning examination and thus being eligible for all measurements.