TABLE 1.

Distribution of birth head circumference Z-score groups in relation to social and demographic characteristics of mother

Maternal characteristic		Head circumference Z-scorea		n
		<−2	≥−2 to <−1
Racial identity	White	7	18	821
	Black	12	27	419
	Other	13	28	181
Hispanic	Yes	10	23	175
	No	9	21	1258
Age, y	<21	11	26	206
	21–35	11	22	930
	>35	7	18	245
Education, y	<12	9	23	235
	12 (HS)	11	26	378
	>12 to <16	11	21	332
	16 (College)	9	18	234
	>16	6	16	171
Marital status	Single	10	27	639
	Not single	9	18	806
Self-supportb	Yes	9	22	891
	No	10	22	181
Medicaidb	Yes	10	26	578
	No	9	19	803
Prepregnancy BMI	<18.5	8	19	106
	≥18.5 to <25	8	20	650
	≥25 to <30	11	25	279
	≥30	12	24	312
Maximum no. of infants		138	317	1445

These are row percents. They do not total to 100% because group with larger Z-scores is not shown.

BMI, body mass index; HS, high school.

^aExternal standard is Oxford, United Kingdom, dataset;¹¹

^bInfants may be in >1 category.

McElrath. Factors associated with small head circumference at birth among ELGAN. Am J Obstet Gynecol 2010.