Table 1.
Cox-proportional hazard models
| Age of First Pregnancy (n = 425, obs = 639, preg = 87) |
Time to Next Pregnancy (n = 561, obs = 1623, preg = 405) |
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|---|---|---|---|---|---|---|
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|
|
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| Variable | Exp(β) | 95% CI | p | Exp(β) | 95% CI | p |
| Age (decades)* | -- | -- | -- | 1.00 | (0.80–1.25) | 0.992 |
| Age4 (decades)* | -- | -- | -- | 0.95 | (0.93–0.96) | <0.001 |
| Hookworm | 0.34 | (0.20–0.58) | <0.001 | 0.74 | (0.60–0.91) | 0.004 |
| A. lumbricoides† | 3.06 | (1.91–4.91) | <0.001 | 1.64 | (1.16–2.33) | 0.005 |
| A. lumbricoides × Age* | -- | -- | -- | 0.68 | (0.51–0.89) | 0.006 |
| Treatment with antihelminthic | 0.43 | (0.19–0.97) | 0.042 | 0.75 | (0.58–0.97) | 0.027 |
| Education (Years) | -- | -- | -- | 0.92 | (0.86–0.99) | 0.017 |
| Speaks Spanish | -- | -- | -- | 0.74 | (0.57–0.95) | 0.018 |
| Distance to town (10km) | -- | -- | -- | 0.96 | (0.91–1.00) | 0.075 |
| Season (P-spline) | -- | -- | <0.001 | -- | -- | <0.001 |
Models also include GEE cluster terms for individual and village. See tables S2–S3 for additional excluded variables.
*
Age is centered at 20 years. Age was continuous to the nearest tenth of a year, but is shown in decades to make the parameters more easily interpretable.
†
For the time to next pregnancy model the roundworm parameter represents the hazard ratio at age 20.