TABLE 1.
Maternal and infant characteristics per cluster group, ordered as clusters 1–3 based on decreasing concentrations of inflammatory fatty acids and amines1
| Characteristics | Cluster 1 (n = 46) | Cluster 2 (n = 94) | Cluster 3 (n = 105) | P | β-coefficient2 | OR (95% CI) |
| Maternal characteristics | ||||||
| Age at enrollment, y | 25.6 ± 5.37 | 28.1 ± 5.26 | 27.3 ± 5.51 | 0.017 | 0.074 | 1.077 (1.013, 1.15) |
| Gestational age at enrollment, d | 99.8 ± 19.3 | 96.2 ± 21.5 | 96.8 ± 18.9 | 0.31 | 0.0083 | 0.99 (0.98, 1.01) |
| Education | ||||||
| Graduate school | 3 (6.52) | 20 (21.28) | 17 (16.19) | 0.012 | 1.91 | 6.78 (1.87, 32.63) |
| College graduate | 7 (15.22) | 18 (19.15) | 22 (20.95) | 1.15 | 3.14 (1.076, 9.74) | |
| Junior college or some college | 8 (17.39) | 26 (27.66) | 30 (28.57) | 1.35 | 3.85 (1.37, 11.3) | |
| Technical school | 2 (4.35) | 4 (4.25) | 6 (5.72) | 1.01 | 2.75 (0.59, 20.02) | |
| High school graduate? | ||||||
| Yes | 15 (32.61) | 15 (15.96) | 21 (20.00) | 0.28 | 1.32 (0.5, 3.42) | |
| No | 11 (23.91) | 11 (11.70) | 9 (8.57) | — | ||
| Household income, $/y | ||||||
| >150,000 | 1 (2.17) | 4 (4.26) | 5 (4.76) | 0.2 | 0.74 | 2.089 (0.35, 40.25) |
| 100,000–149,999 | 3 (6.52) | 6 (6.38) | 14 (13.33) | 0.44 | 1.55 (0.44, 7.25) | |
| 75,000–99,999 | 5 (10.87) | 15 (15.96) | 9 (8.57) | 0.11 | 1.11 (0.37, 3.78) | |
| 50,000–74,999 | 1 (2.17) | 14 (14.89) | 7 (6.67) | 1.58 | 4.88 (0.89, 91.27) | |
| 30,000–49,999 | 6 (13.05) | 10 (10.64) | 17 (16.19) | 0.044 | 1.045 (0.37, 3.25) | |
| Other or unreported | 17 (36.96) | 19 (20.21) | 23 (21.91) | −0.56 | 0.57 (0.25, 1.3) | |
| <30,000 | 13 (28.26) | 26 (27.66) | 30 (28.57) | — | ||
| Marital status | ||||||
| Married | 20 (43.48) | 47 (50.00) | 50 (47.62) | 0.34 | 0.19 | 1.21 (0.55, 2.61) |
| Separated or divorced | 0 (0) | 3 (3.19) | 3 (2.86) | 15.18 | NA | |
| Not married | ||||||
| Living together | 13 (28.26) | 23 (24.47) | 21 (20.00) | −0.17 | 0.85 (0.35, 2.03) | |
| Not living together | 13 (28.26) | 21 (22.34) | 31 (29.52) | — | ||
| Treatment arm | ||||||
| Vitamin D | 21 (45.65) | 47 (50.00) | 51 (48.57) | 0.66 | 0.14 | 1.16 (0.61, 2.21) |
| Placebo | 25 (54.35) | 47 (50.00) | 54 (51.42) | — | ||
| Infant characteristics | ||||||
| Sex | ||||||
| Female | 26 (56.52) | 51 (54.26) | 56 (53.33) | 0.74 | −0.111 | 0.9 (0.47, 1.7) |
| Male | 20 (43.48) | 43 (45.74) | 49 (46.67) | — | ||
| Ethnicity | ||||||
| Asian | 2 (4.35) | 7 (7.45) | 5 (4.76) | 0.098 | 0.73 | 2.07 (0.52, 13.78) |
| Caucasian | 10 (21.74) | 32 (34.04) | 36 (34.29) | 0.85 | 2.34 (1.1, 5.36) | |
| Native Hawaiian | 0 (0.00) | 1 (1.06) | 2 (1.91) | 14.5 | NA | |
| Other | 4 (8.69) | 14 (14.90) | 15 (14.28) | 0.92 | 2.5 (0.89, 8.94) | |
| African American | 30 (65.22) | 40 (42.55) | 47 (44.76) | — | ||
| Length at birth, cm | 50.5 ± 2.74 | 51.2 ± 2.79 | 51.0 ± 2.41 | 0.19 | 0.082 | 1.085 (0.96, 1.23) |
| Weight at birth, kg | 3.24 ± 0.49 | 3.41 ± 0.5 | 3.34 ± 0.51 | 0.11 | 0.00051 | 1 (1, 1) |
| BMI, kg/m2 | 12.6 (9.80−15.40) | 12.95 (9.69−17.25) | 12.78 (8.93−16.41) | 0.28 | 0.13 | 1.14 (0.9, 1.46) |
| Mode of delivery | ||||||
| Cesarean | 17 (36.96) | 59 (62.77) | 34 (32.38) | 0.68 | −0.18 | 0.83 (0.43, 1.66) |
| Vaginal | 27 (58.70) | 31 (32.98) | 65 (61.9) | — | ||
| With previous cesarean | 1 (2.17) | 1 (1.06) | 0 (0.0) | −1.52 | 0.22 (0.0084, 5.62) | |
| Forceps assisted | 0 (0.0) | 0 (0.0) | 2 (1.91) | 14.042 | NA | |
| Vacuum assisted | 1 (2.17) | 3 (3.19) | 4 (3.81) | 0.42 | 1.52 (0.26, 29.1) | |
| Infant still being breastfed | ||||||
| Month 12 | 11 (23.91) | 25 (26.60) | 25 (23.81) | 0.18 | −1.26 | 0.28 (0.015, 1.64) |
| Since last visit (month 24) | 34 (73.91) | 78 (82.98) | 84 (80.00) | 0.19 | 0.52 | 1.68 (0.79, 3.52) |
| Since last visit (month 33) | 33 (71.74) | 75 (79.78) | 84 (80.00) | 0.19 | 0.5 | 1.65 (0.77, 3.38) |
| Vitamin D at 3 y, ng/mL | 16.6 ± 7.25 | 21.9 ± 9.24 | 22.0 ± 8.76 | 0.00008 | 0.086 | 1.09 (1.042, 1.14) |
| Sample characteristics | ||||||
| Sample storage time, y | 5.75 ± 0.5 | 5.57 ± 0.5 | 5.50 ± 0.52 | 0.0097 | −0.84 | 0.43 (0.22, 0.82) |
Values are means ± SDs or n (%) unless otherwise indicated. Characteristics showing evidence of confounding of cluster membership included mother’s age at enrollment, mother’s educational level, child’s vitamin D concentration at age 3 y, and sample storage time, but no statistically significant differences across the clusters with respect to sex, ethnicity, anthropometrics, vaginal compared with cesarean delivery, or breastfeeding patterns. All P values were derived by applying χ2ANOVA to each multinomial logistic regression model, with sample-to-cluster assignment as the outcome and each characteristic as the predictor of this. All P values, β-coefficients, and ORs are derived from χ2 ANOVA on a multinomial logistic regression model with sample-to-cluster assignment as outcome, with levels ordered as clusters 1–3 (i.e., decreasing concentrations of inflammatory fatty acids and amines). Reference categories were mother’s education, did not graduate from high school; household income, <$30,000/y; mother’s marital status, not married and not living together; treatment arm, placebo; sex, male; ethnicity, African American; infant still being breastfed (month 12), no; infant breastfed since last visit (month 24), no; infant breastfed since last visit (month 33), no; mode of delivery, vaginal. NA, not applicable.
The β-coefficient is the rate of change of each maternal and infant characteristic per unit change in the outcome of interest.