Table 1.

Mother–child pair characteristics of the study sample, overall and stratified by child sex, from the Project Viva cohort in Boston, Massachusetts.

Mother–child pair characteristic	Overall $n$ (%) or $\text{mean}\pm \text{SD}$	Male $n$ (%) or $\text{mean}\pm \text{SD}$	Female $n$ (%) or $\text{mean}\pm \text{SD}$
$n$	900	464	436
Maternal self-reported race/ethnicity
NH White	679 (75.4%)	349 (75.2%)	330 (75.7%)
NH Black	88 (9.8%)	41 (8.8%)	47 (10.8%)
Hispanic	57 (6.3%)	34 (7.3%)	23 (5.3%)
NH Asian	39 (4.3%)	22 (4.7%)	17 (3.9%)
More than one race/ethnicity	37 (4.1%)	18 (3.9%)	19 (4.4%)
Maternal education
College graduate	663 (73.7%)	337 (72.6%)	326 (74.8%)
Less than college graduate	237 (26.3%)	127 (27.4%)	110 (25.2%)
Annual household income
$>\text{USD\hspace{0.17em}}\$\mathrm{70,000}$	579 (64.3%)	302 (65.1%)	277 (63.5%)
$\le \text{USD\hspace{0.17em}}\$\mathrm{70,000}$	321 (35.7%)	162 (34.9%)	159 (36.5%)
Maternal smoking
Never smoked	616 (68.4%)	311 (67.0%)	305 (70.0%)
Former smoker	188 (20.9%)	95 (20.5%)	93 (21.3%)
Smoked during pregnancy	96 (10.7%)	58 (12.5%)	38 (8.7%)
Hemolysis or lipemia of blood during folate or vitamin B12 measurement
Yes	156 (17.3%)	87 (18.8%)	69 (15.8%)
No	744 (82.7%)	377 (81.3%)	367 (84.2%)
Maternal prepregnancy BMI (${\mathrm{kg}/\mathrm{m}}^2$)	$24.7\pm 5.2$	$24.8\pm 5.3$	$24.7\pm 5.1$
Maternal age at enrollment (y)	$32.7\pm 4.6$	$32.5\pm 4.6$	$32.8\pm 4.5$
Maternal first-trimester fish consumption, servings/week	$1.68\pm 1.41$	$1.64\pm 1.40$	$1.72\pm 1.42$
Maternal Prudent diet index	$0.000211\pm 0.926$	$-0.0213\pm 0.926$	$0.0231\pm 0.927$
Maternal hematocrit (%)	$70.8\pm 26.0$	$70.9\pm 25.7$	$70.7\pm 26.4$
Early childhood visit ($n=834$)
Maternal receptive vocabulary (PPVT-III)	$107\pm 14.1$	$107\pm 14.3$	$107\pm 14.0$
Child age (y)	$3.25\pm 0.29$	$3.25\pm 0.27$	$3.25\pm 0.30$
Overall visual-motor (WRAVMA summary) ($n=793$)a	$103\pm 11.4$	$100\pm 11.4$	$105\pm 10.8$
Visual-motor (WRAVMA) ($n=825$)a	$99.2\pm 11.3$	$96.7\pm 10.6$	$102\pm 11.4$
Fine-motor (WRAVMA) ($n=818$)a	$98.2\pm 10.8$	$96.8\pm 11.0$	$99.7\pm 10.4$
Visual-spatial (WRAVMA) ($n=796$)a	$109\pm 13.6$	$107\pm 13.4$	$111\pm 13.5$
Receptive vocabulary (PPVT-III) ($n=810$)a	$105\pm 13.8$	$104\pm 14.2$	$107\pm 13.3$
Mid-childhood visit ($n=705$)
Maternal overall intelligence (KBIT-II composite)	$109\pm 14.4$	$109\pm 14.9$	$108\pm 13.8$
Child age (y)	$7.92\pm 0.81$	$7.93\pm 0.80$	$7.90\pm 0.83$
Overall visual memory (WRAML2 total) ($n=701$)a	$17.0\pm 4.4$	$16.8\pm 4.6$	$17.2\pm 4.3$
Design memory (WRAML2) ($n=703$)a	$8.09\pm 2.78$	$8.16\pm 2.94$	$8.03\pm 2.62$
Picture memory (WRAML2) ($n=702$)a	$8.89\pm 3.02$	$8.66\pm 3.00$	$9.13\pm 3.03$
Visual-motor (WRAVMA) ($n=699$)a	$92.7\pm 16.7$	$90.7\pm 16.8$	$94.6\pm 16.4$
Crystallized intelligence (KBIT-II non-verbal) ($n=705$)a	$108\pm 16.8$	$107\pm 16.8$	$108\pm 16.8$
Fluid intelligence (KBIT-II verbal) ($n=697$)a	$114\pm 14.0$	$113\pm 14.4$	$115\pm 13.6$

Note: BMI, body mass index; CI, confidence interval; KBIT-II, Kaufman Brief Intelligence Test, 2nd edition; NH, non-Hispanic; PPVT-III, Peabody Picture Vocabulary Test, 3rd edition; SD, standard deviation; WRAML2, Wide Range Assessment of Memory and Learning, 2nd edition; WRAVMA, Wide Range Assessment of Visual Motor Abilities.

^a n Denotes number of mother-child pairs included in analyses of the outcome, i.e., with data on at least one exposure, the indicated outcome, and all covariates.