. 2018 Dec 28;134(2):155–163. doi: 10.1177/0033354918821078

Table 4.

Percentage of study participants in selected risk groups^a who had low dietary intake or high dietary intake^b of selected nutritional factors, by maternal education, household income, race/ethnicity, and pregnancy intention, and whether these percentages were significantly different from the reference groups, among control mothers who participated in the National Birth Defects Prevention Study, 1997–2011^c

	Education <High School Diploma^d		Annual Household Income ≤$20 000^e		Race/Ethnicity^f				Did Not Intend to Become Pregnant^g
	Education <High School Diploma^d		Annual Household Income ≤$20 000^e		Non-Hispanic Black		Hispanic		Did Not Intend to Become Pregnant^g
Factor	% Low	% High	% Low	% High	% Low	% High	% Low	% High	% Low	% High
Positively scored factors
Diet quality index^h	12.1ⁱ	6.8ⁱ	12.5ⁱ	7.0ⁱ	18.2ⁱ	7.9	5.1^j	9.0ⁱ	14.2ⁱ	8.2ⁱ
Nutrients
Beta carotene	15.4ⁱ	8.7	14.9ⁱ	8.1ⁱ	17.3ⁱ	11.6^j	10.0ⁱ	11.4^j	15.0ⁱ	9.5
Calcium	14.7ⁱ	5.7ⁱ	14.2ⁱ	7.3ⁱ	19.6ⁱ	5.0ⁱ	10.4ⁱ	5.6ⁱ	15.8ⁱ	5.5ⁱ
Choline	14.0ⁱ	12.3^j	13.7ⁱ	11.6^j	13.9ⁱ	14.2^j	7.0^j	13.7^j	13.8ⁱ	12.6^j
Folate	12.5ⁱ	9.3	12.8ⁱ	9.5	13.5ⁱ	11.2	7.4^j	8.6ⁱ	11.8ⁱ	9.7
Iron	11.2ⁱ	10.9	12.0ⁱ	10.4	13.0ⁱ	11.6^j	7.0^j	10.7	10.3	11.8^j
Lycopene	17.3ⁱ	17.5^j	15.4ⁱ	13.6^j	24.4ⁱ	2.3ⁱ	10.6ⁱ	25.1^j	14.1ⁱ	12.9^j
Niacin	18.9ⁱ	7.6ⁱ	16.5ⁱ	8.1ⁱ	10.8ⁱ	14.1^j	13.0ⁱ	7.4ⁱ	11.4ⁱ	9.7
Retinol	13.8ⁱ	15.8^j	12.2ⁱ	13.8^j	10.9ⁱ	15.5^j	12.6ⁱ	14.5^j	12.9ⁱ	13.1^j
Riboflavin	14.3ⁱ	7.7ⁱ	14.4ⁱ	7.7ⁱ	16.3ⁱ	8.2ⁱ	9.1	6.5ⁱ	12.4ⁱ	9.1
Thiamin	13.6ⁱ	10.0	13.7ⁱ	9.7	13.6ⁱ	13.9^j	7.8^j	9.1	12.6ⁱ	10.7
Vitamin A	15.7ⁱ	14.3^j	14.3ⁱ	12.0^j	13.2ⁱ	14.1^j	12.4ⁱ	15.3^j	14.9ⁱ	12.2^j
Vitamin C	9.6	16.8ⁱ	11.1ⁱ	13.6^j	10.7	14.0^j	4.0^j	17.7^j	12.0ⁱ	12.1^j
Fruits	10.5	15.1^j	11.6ⁱ	12.3^j	13.4ⁱ	12.8^j	4.3^j	16.9^j	13.6ⁱ	10.6
Vegetables	16.7ⁱ	13.2^j	15.9ⁱ	10.6^j	19.4ⁱ	6.0	11.9ⁱ	17.0^j	15.2ⁱ	11.5^j
Dairy	13.0ⁱ	6.5ⁱ	13.1ⁱ	7.8ⁱ	18.2ⁱ	4.6ⁱ	9.5	6.0ⁱ	14.0ⁱ	6.6ⁱ
Grains	13.2ⁱ	10.7	12.6ⁱ	10.5^j	14.4ⁱ	13.5^j	9.5	10.0^j	11.9ⁱ	12.2^j
% Calories from protein	18.1ⁱ	5.5ⁱ	16.2ⁱ	6.9ⁱ	16.8ⁱ	11.3	11.1ⁱ	6.4ⁱ	13.9ⁱ	9.7
Negatively scored factors
Sweets	7.8ⁱ	15.5ⁱ	7.8ⁱ	15.3ⁱ	8.6	16.1ⁱ	9.6	8.2^j	9.0	14.7ⁱ
Glycemic index	13.8^j	13.2ⁱ	9.7	14.3ⁱ	4.2ⁱ	20.7ⁱ	16.3^j	4.9^j	8.0ⁱ	15.8ⁱ
% Calories from fat	16.3^j	6.3^j	13.5^j	8.8^j	11.7^j	12.1	15.0^j	4.8^j	12.2^j	10.7
% Calories from saturated fat	16.7^j	6.0^j	14.5^j	8.5^j	13.4^j	10.0	16.1^j	3.5^j	13.1^j	10.2

^a Risk groups were defined on the basis of selected characteristics associated with adverse maternal and infant health outcomes.

^b High intake refers to dietary intake >90th percentile, and low intake refers to dietary intake <10th percentile; percentiles were based on the distribution of dietary intake among all study participants (Table 1 presents percentile cutoffs).

^c Data source: Yoon et al.¹⁴

^d Reference group was participants with a high school diploma or greater education.

^e Reference group was participants with annual household income >$20 000.

^f Reference group was non-Hispanic white.

^g Reference group was participants who did intend to become pregnant.

^h A summary score of 6 positively scored components (grains, vegetables, fruits, folate, iron, and calcium) and 2 negatively scored components (intake of sweets and percentage of calories from fat). For each participant, we scored each component from 0 to 3 on the basis of quartiles of the distribution among controls, and then we summed the component scores to obtain the final value for the diet quality index; the score could range from 0 to 18, and a higher score indicates better diet quality. Index is based on a previously validated index^17,18 adapted to the National Birth Defects Prevention Study food frequency questionnaire.¹⁹

ⁱ Risk group had significantly (P < .05) worse intake than the reference group, as determined by Pearson χ² tests. That is, for positively scored nutrients, a larger percentage of participants than expected had low intake (ie, >10% had intake <10th percentile) or a smaller percentage of participants than expected had high intake (ie, <10% had intake >90th percentile). For negatively scored nutrients, a smaller percentage of participants than expected had low intake (ie, <10% had intake <10th percentile) or a larger percentage of participants than expected had high intake (ie, >10% had intake >90th percentile).

^j Risk group had significantly (P < .05) better intake than reference group, as determined by Pearson χ² tests. For positively scored nutrients, a smaller percentage of participants than expected had low intake (ie, <10% had intake <10th percentile) or a larger percentage of participants than expected had high intake (ie, >10% had intake >90th percentile). For negatively scored nutrients, a larger percentage of participants than expected had low intake (ie, >10% had intake <10th percentile) or a smaller percentage of participants than expected had high intake (ie, <10% had intake >90th percentile).