Table 1.
Baseline characteristics of pregnant women (with liveborn children) by study group
| Characteristic | Intervention (N=1536) |
Control (N=1525) |
|
|---|---|---|---|
| IRC, n (%) | Guatemala | 384 (25.0%) | 386 (25.3%) |
| India | 388 (25.3%) | 387 (25.4%) | |
| Peru | 385 (25.1%) | 358 (23.5%) | |
| Rwanda | 379 (24.7%) | 394 (25.8%) | |
| Missing, n | 0 | 0 | |
| Mother’s age (years) at baseline | Mean (SD) | 25.3 (4.4) | 25.4 (4.5) |
| 18 to <25 years, n (%) | 787 (51.2%) | 758 (49.7%) | |
| 25 to <30 years, n (%) | 484 (31.5%) | 488 (32.0%) | |
| 30 to <35 years, n (%) | 265 (17.3%) | 279 (18.3%) | |
| Missing, n | 0 | 0 | |
| Mother’s highest level of education completed, n (%) | None or some primary | 461 (30.0%) | 540 (35.4%) |
| Primary or some secondary | 538 (35.0%) | 514 (33.7%) | |
| Secondary, vocational, or university/college | 537 (35.0%) | 471 (30.9%) | |
| Missing, n | 0 | 0 | |
| Gestational age (weeks) at baseline | Mean (SD) | 15.5 (3.1) | 15.3 (3.2) |
| Missing, n | 0 | 0 | |
| Gestational age (weeks) at intervention1 | Mean (SD) | 18.1 (3.3) | 17.9 (3.2) |
| 10 to <18 weeks | 767 (49.9%) | 791 (51.9%) | |
| 18 to <30 weeks | 769 (50.1%) | 734 (48.1%) | |
| Missing, n | 0 | 0 | |
| Number of siblings in the household | Mean (SD) | 1.0 (1.1) | 1.1 (1.2) |
| Missing, n | 0 | 0 | |
| Second-hand Smoking | n (%) | 146 (9.5%) | 174 (11.4%) |
| Missing, n | 1 | 2 | |
| Household food insecurity score2, n (%) | Food secure | 904 (58.9%) | 820 (53.8%) |
| Mild | 403 (26.2%) | 424 (27.8%) | |
| Moderate/severe | 208 (13.5%) | 259 (17.0%) | |
| Missing, n | 21 | 22 | |
| Socioeconomic status index3 | Mean (SD) (range) | −0.1 (1.1) (−2.2, 2.1) | 0.1 (1.0) (−2.2, 2.1) |
| Missing, n | 0 | 0 | |
| PM2.5 (μg/m3)4 | Median (IQR) | 81.6 (45.9, 150.7) | 84.2 (46.5, 143.0) |
| Missing, n | 184 | 173 | |
| Black carbon (μg/m3)4 | Median (IQR) | 10.5 (6.2, 15.4) | 10.9 (6.9, 15.5) |
| Missing, n | 313 | 314 | |
| Carbon monoxide (ppm)4 | Median (IQR) | 1.3 (0.5, 3.0) | 1.2 (0.5, 2.5) |
| Missing, n | 152 | 150 | |
IRC indicates International Research Center; SD, standard deviation; PM, particulate matter; IQR, interquartile range.
Control group calculated as gestational age at baseline plus 2.6 weeks, which is the average time between baseline and stove installation in the intervention group.
Categories (corresponding score): Food secure (0); Mild (1,2,3), Moderate (4,5,6) or Severe (7,8) food insecurity.
Principal component analysis was applied to data on number of people in the household, participant’s education level, quality of water and sanitation, access to electricity, housing materials, ownership of 24 specific household assets and food insecurity at the start of the study. Multiple imputation with chained equations was used to handle missing data. A higher index indicates worse socioeconomic status.
Missing includes invalid samples that failed to pass quantitative quality checks, including samples with unacceptable flow rates, filter damage, and measurement durations outside of 24 ± 4 hours.