Adjusted relative risk of LBW, preterm birth and SGA among women who moved in the first trimester of pregnancy compared with those who did not move, stratified by socioeconomic status proxy variables
| Variable | n* | LBW RR (95% CI) | Preterm birth RR (95% CI) | SGA RR (95% CI) |
| Education† | ||||
| Less than high school | 19 633 | 1.50 (1.32 to 1.70) | 1.51 (1.35 to 1.70) | 1.13 (1.01 to 1.25) |
| High school/some college or associate’s degree | 79 144 | 1.38 (1.28 to 1.48) | 1.49 (1.40 to 1.58) | 0.98 (0.92 to 1.04) |
| Bachelor’s degree or more | 41 529 | 1.25 (1.10 to 1.42) | 1.20 (1.08 to 1.34) | 1.16 (1.06 to 1.28) |
| Payer† | ||||
| Medicaid | 53 099 | 1.40 (1.29 to 1.52) | 1.46 (1.36 to 1.56) | 1.01 (0.95 to 1.08) |
| Private/government/ self-pay | 79 121 | 1.33 (1.22 to 1.45) | 1.41 (1.31 to 1.51) | 1.08 (1.01 to 1.15) |
| Other | 8086 | 1.39 (1.15 to 1.69) | 1.36 (1.15 to 1.61) | 1.00 (0.86 to 1.18) |
| Median household income of census tract ($)† | ||||
| <40 000 | 51 914 | 1.46 (1.34 to 1.59) | 1.42 (1.32 to 1.53) | 1.06 (0.99 to 1.14) |
| 40 000–49 999 | 34 823 | 1.37 (1.22 to 1.54) | 1.37 (1.24 to 1.51) | 1.09 (0.98 to 1.17) |
| 50 000–59 999 | 25 833 | 1.18 (1.01 to 1.36) | 1.51 (1.34 to 1.70) | 1.02 (0.90 to 1.14) |
| 60 000+ | 27 736 | 1.32 (1.14 to 1.52) | 1.46 (1.29 to 1.64) | 1.00 (0.89 to 1.12) |
*Analyses for LBW and SGA were slightly smaller than that for preterm birth due to missing values of these two outcomes. Analyses of LBW contained 27 997 movers and 112 367 non-movers. Analyses of SGA contained 27 985 movers and 112 321 non-movers.
†Models controlled for age (continuous), marital status (married/unmarried), parity (nulliparous, primiparous, multiparous), maternal race (Asian/Pacific Islander, Black, Hispanic (non-white), Native American/Alaska Native, white), smoking (yes/no), median household income of census tract (less than $40 000, $40 000–$49 999, $50 000–$59 999, over $60 000), payer (Medicaid, private/government/self-pay, other) and maternal education (less than high school, completed high school or some college/associate’s degree, bachelor's degree or more). Variables were not included as confounders when they were the stratifying variable.
LBW, low birth weight;RR, relative risk; SGA, small for gestational age.