From: Interpregnancy interval and adverse birth outcomes: a population-based cohort study of twins
Outcome Variable and Cohort | Interpregnancy Interval (months) | |||||||
---|---|---|---|---|---|---|---|---|
aRR [95% CI]c | ||||||||
< 6 | 6–11 | 12–17 | 18–23 | 24–59 | 60–119 | ≥ 120 | ||
Preterm Birth | IPIa | 1.05 [0.94–1.18] | 0.99 [0.90–1.08] | 0.97 [0.89–1.05] | 1 [referent] | 1.04 [0.97–1.12] | 1.12 [1.02–1.22]** | 1.25 [1.10–1.41]*** |
Post-Birth IPIa | 1.37 [1.22–1.53]*** | 1.22 [1.10–1.36]*** | 1.08 [0.97–1.20] | 1 [referent] | 1.01 [0.92–1.11] | 0.96 [0.85–1.08] | 0.98 [0.80–1.21] | |
RoRb | 0.77 [0.66–0.91] | 0.81 [0.70–0.93] | 0.90 [0.79–1.03] | 1 [referent] | 1.03 [0.92–1.16] | 1.17 [1.01–1.35] | 1.27 [1.00–1.62] | |
Early Preterm Birth | IPI | 1.41 [1.08–1.83]* | 1.17 [0.94–1.46] | 0.99 [0.80–1.23] | 1 [referent] | 1.16 [0.96–1.39] | 1.19 [0.94–1.51] | 1.42 [1.01–2.00]* |
Post-Birth IPI | 2.03 [1.61–2.55]*** | 1.45 [1.16–1.81]** | 0.99 [0.78–1.26] | 1 [referent] | 0.88 [0.72–1.07] | 0.84 [0.66–1.08] | 0.73 [0.45–1.19] | |
RoR | 0.69 [0.49–0.99] | 0.81 [0.59–1.10] | 1.00 [0.73–1.38] | 1 [referent] | 1.32 [1.01–1.73] | 1.41 [1.01–2.00] | 1.94 [1.08–3.53] | |
Small for Gestational Age | IPI | 1.20 [0.90–1.59] | 1.24 [1.01–1.54]* | 1.14 [0.93–1.40] | 1 [referent] | 1.14 [0.95–1.36] | 1.19 [0.95–1.51] | 1.30 [0.90–1.86] |
Post-Birth IPI | 1.50 [1.17–1.92]*** | 1.13 [0.90–1.42] | 0.85 [0.67–1.08] | 1 [referent] | 0.86 [0.71–1.05] | 0.90 [0.71–1.14] | 0.93 [0.61–1.41] | |
RoR | 0.80 [0.55–1.16] | 1.10 [0.80–1.50] | 1.34 [0.98–1.83] | 1 [referent] | 1.32 [1.01–1.72] | 1.33 [0.95–1.85] | 1.39 [0.80–2.42] | |
Low Birth Weight | IPI | 1.16 [1.06–1.28]** | 1.09 [1.01–1.19]* | 1.01 [0.93–1.09] | 1 [referent] | 1.06 [0.99–1.14] | 1.17 [1.08–1.28]*** | 1.20 [1.05–1.36]** |
Post-Birth IPI | 1.30 [1.19–1.42]*** | 1.17 [1.07–1.27]*** | 1.03 [0.94–1.12] | 1 [referent] | 1.01 [0.93–1.09] | 0.99 [0.90–1.09] | 0.87 [0.72–1.05] | |
RoR | 0.90 [0.78–1.02] | 0.93 [0.83–1.05] | 0.98 [0.87–1.11] | 1 [referent] | 1.05 [0.95–1.17] | 1.19 [1.05–1.35] | 1.38 [1.10–1.73] |