Table 1.

Sample Characteristics for US Women Aged 20 to 40 Years by Pregnancy Status in the National Health and Nutrition Examination Survey, 2001-2014

CharacteristicNonpregnant and Nonlactating Women, Mean (SE) (n = 5523)Pregnant and Nonlactating Women, Mean (SE) (n = 1003)
Age, y30.0 (0.2)28.0 (0.3)a
Trimester of pregnancy, %
FirstNA26.5 (2.5)
SecondNA36.0 (3.1)
ThirdNA37.5 (3.0)
Race/ethnicity, %b
Non-Hispanic white62.0 (1.6)54.5 (3.1)a
Hispanic or Mexican17.2 (1.1)19.7 (2.3)
Non-Hispanic black13.8 (0.9)17.5 (2.2)
Educational level, %
High school or GED or less36.9 (1.2)39.2 (2.6)
Some college but no degree37.3 (0.9)31.5 (2.3)a
Undergraduate degree or higher25.8 (1.0)29.2 (2.6)
Income to poverty ratio, %
≤13031.0 (1.1)29.8 (2.3)
131 to <18511.8 (0.5)13.4 (1.7)
≥18557.2 (1.1)56.8 (3.0)
Physical activity, %c
Sedentary21.9 (0.8)33.3 (2.8)a
Moderate35.0 (1.0)48.9 (2.8)a
Vigorous43.1 (1.3)17.8 (2.1)a
Dietary supplement use, %47.1 (1.1)69.8 (2.3)a
Alcohol use, %21.7 (0.9)3.4 (0.7)a
Smoking currently, %20.3 (0.9)5.9 (1.1)a

Abbreviations: GED, general equivalency diploma; NA, not applicable.

aMeans or proportions are significantly different (P < .05).

bRace/ethnicity does not sum to 100% because the “other” category is not presented per National Center for Health Statistics analytical guidelines.

cPhysical activity level was divided into 3 groups based on number of days in which there was hard exercise using the Physical Activity Questionnaire responses.