Table 1.
Distribution of study variables
| Variable | Mean (SD)
|
||
|---|---|---|---|
| Total | Low SES | High SES | |
| Child developmental risk status (high versus low)a | 0.181 (0.395) | 0.217 (0.142) | 0.145 (0.352) |
| Child neurodevelopment ratea | 0.00 (14.581) | −1.596 (15.157) | 1.620 (13.793) |
| Maternal smoking during pregnancy | 0.109 (0.311) | 0.154 (0.361) | 0.062 (0.242) |
| Number of cigarettes per day during pregnancy | 0. 754 (3.007) | 1.175 (3.827) | 0.326 (1.733) |
| African ancestry | 0.154 (0.361) | 0.211 (0.408) | 0.097 (0.296) |
| Native ancestry | 0.426 (0.495) | 0.451 (0.498) | 0.399 (0.490) |
| Birth weight (in 100 grams) | 33.47 (4.26) | 33.30 (4.31) | 33.64 (4.21) |
| Gestational age (in weeks) | 39.3 (1.05) | 39.39 (1.04) | 39.21 (1.05) |
| Socioeconomic status index | −0.002 (1.238) | −0.954 (0.819) | 0.965 (0.741) |
| Completed primary schoolb | 0.298 (0.458) | 0.530 (0.500) | 0.062 (0.242) |
| Incomplete secondary schoolb | 0.199 (0.399) | 0.274 (0.447) | 0.122 (0.328) |
| Complete secondary schoolb | 0.306 (0.461) | 0.177 (0.382) | 0.438 (0.496) |
| Attended universityb | 0.197 (0.398) | 0.019 (0.136) | 0.378 (0.485) |
| Unemployedc | 0.639 (0.480) | 0.801 (0.400) | 0.475 (0.500) |
| Unskilled blue collar workerc | 0.074 (0.263) | 0.109 (0.312) | 0.039 (0.195) |
| Skilled blue collar workerc | 0.042 (0.201) | 0.021 (0.144) | 0.064 (0.244) |
| Independent workerc | 0.042 (0.201) | 0.023 (0.149) | 0.062 (0.242) |
| Clerkc | 0.136 (0.343) | 0.045 (0.208) | 0.229 (0.420) |
| Wealth index | 0.038 (0.981) | −0.624 (0.87) | 0.71 (0.524) |
| Maternal mental health problems | 0.037 (0.188) | 0.045 (0.208) | 0.028 (0.165) |
| Maternal chronic physical health problems | 0.052 (0.222) | 0.050 (0.218) | 0.053 (0.225) |
| Maternal age | 27.076 (6.571) | 25.197 (6.267) | 28.985 (6.322) |
| Maternal age squared | 776.287 (376.990) | 674.099 (345.748) | 880.036 (379.256) |
| Mother is single | 0.169 (0.374) | 0.212 (0.409) | 0.125 (0.330) |
| Mother is in a stable relationship | 0.409 (0.492) | 0.509 (0.500) | 0.308 (0.462) |
| Number of older child’s siblings | 1.007 (1.368) | 1.214 (1.553) | 0.796 (1.111) |
| Area smoking rate | 0.109 (0.070) | 0.120 (0.072) | 0.097 (0.066) |
| Area smoking rate squared | 0.016 (0.017) | 0.020 (0.019) | 0.014 (0.015) |
| Area-level average cigarette number | 0.754 (0.740) | 0.875 (0.793) | 0.63 (0.66) |
| Cesarean delivery rate | 0.385 (0.153) | 0.361 (0.158) | 0.410 (0.143) |
| Average number of prenatal visits | 6.997 (1.589) | 6.864 (1.592) | 7.129 (1.577) |
| Average number of weeks delayed before initiating prenatal care | 13.046 (2.745) | 13.364 (2.885) | 12.726 (2.561) |
| Average number of ultrasounds during pregnancy | 2.287 (1.012) | 2.207 (1.057) | 2.367 (0.959) |
| Medication use rate during pregnancy | 0.715 (0.281) | 0.684 (0.286) | 0.747 (0.272) |
| Immunization rate during pregnancy | 0.548 (0.294) | 0.581 (0.277) | 0.516 (0.308) |
| Brazild | 0.331 (0.471) | 0.381 (0.486) | 0.281 (0.450) |
| Chiled | 0.245 (0.430) | 0.167 (0.373) | 0.321 (0.468) |
Note: The table reports the means and standard deviation of the study variables.
a
Derived from the Bayley Infant Neurodevelopment Screener. Copyright @ 2004. Harcourt Assessment Inc. Used with Permission. All rights Reserved.
b
The reference category is incomplete primary schooling or lower education.
c
The reference category is executive, professional, or owner occupation.
d
The reference country is Argentina.