Table 2.
Crude and Adjusted* Odds Ratios for Preeclampsia and Hypertensive Disorder of Pregnancy (Study Definition)† According to Apnea-Hypopnea Index (AHI) in Early and Mid- Pregnancy
| All Apneas and Hypopneas with 3% Oxygen Desaturation / hour | n/N (%) | Crude Odds Ratios | Adjusted Odds Ratios | ||
|---|---|---|---|---|---|
|
| |||||
| Estimate (95% CI) | p-value | Estimate (95% CI) | p-value | ||
|
| |||||
| Preeclampsia | |||||
| Early Pregnancy (N=3,131) | |||||
| AHI<5 (referent) | 170/3017 (5.6) | 1.00 | <0.001 | 1.00 | 0.03 |
| AHI≥5 | 16/114 (14.0) | 2.73 (1.58–4.74) | 1.94 (1.07–3.51) | ||
| AHI=0 (referent) | 42/763 (5.5) | 1.00 | 0.004 | 1.00 | 0.16 |
| 0<AHI<5 | 128/2254 (5.7) | 1.03 (0.72–1.48) | Trend tests: | 0.96 (0.66–1.39) | |
| 5≤AHI<15 | 14/105 (13.3) | 2.64 (1.39–5.02) | 0.02 linear | 1.79 (0.89–3.61) | |
| AHI≥15 | 2/9 (22.2) | 4.90 (0.99–24.34) | 0.50 quadratic | 2.74 (0.51–14.73) | |
| Mid-pregnancy (N=2,472) | |||||
| AHI<5 (referent) | 114/2266 (5.0) | 1.00 | <0.001 | 1.00 | 0.01 |
| AHI≥5 | 26/206 (12.6) | 2.73 (1.73–4.29) | 1.95 (1.18–3.23) | ||
| AHI=0 (referent) | 15/347 (4.3) | 1.00 | <0.001 | 1.00 | 0.06 |
| 0<AHI<5 | 99/1919 (5.2) | 1.20 (0.69–2.10) | Trend tests: | 1.01 (0.57–1.78) | |
| 5≤ AHI<15 | 21/177 (11.9) | 2.98 (1.50–5.94) | 0.001 linear | 1.83 (0.86–3.89) | |
| AHI ≥15 | 5/29 (17.2) | 4.61 (1.54–13.76) | 0.68 quadratic | 2.95 (0.91–9.58) | |
| HTN Disorder of Pregnancy | |||||
| Early Pregnancy (N=3,131) | |||||
| AHI<5 (referent) | 378/3017 (12.5) | 1.00 | <0.001 | 1.00 | 0.11 |
| AHI≥5 | 28/114 (24.6) | 2.27 (1.46–3.53) | 1.46 (0.91–2.32) | ||
| AHI=0 (referent) | 79/763 (10.4) | 1.00 | <0.001 | 1.00 | 0.29 |
| 0<AHI<5 | 299/2254 (13.3) | 1.32 (1.02–1.72) | Trend tests: | 1.16 (0.88–1.53) | |
| 5≤ AHI<15 | 25/105 (23.8) | 2.71 (1.63–4.49) | 0.02 linear | 1.62 (0.94–2.79) | |
| AHI≥ 15 | 3/9 (33.3) | 4.33 (1.06–17.65) | 0.80 quadratic | 2.17 (0.52–9.14) | |
| Mid-pregnancy (N=2,472) | |||||
| AHI<5 (referent) | 266/2266 (11.7) | 1.00 | <0.001 | 1.00 | 0.004 |
| AHI≥5 | 51/206 (24.8) | 2.47 (1.76–3.48) | 1.73 (1.19–2.52) | ||
| AHI=0 (referent) | 28/347 (8.1) | 1.00 | <0.001 | 1.00 | 0.004 |
| 0<AHI<5 | 238/1919 (12.4) | 1.61 (1.07–2.43) | Trend tests: | 1.31 (0.86–1.99) | Trend tests: |
| 5≤ AHI<15 | 40/177 (22.6) | 3.33 (1.97–5.61) | <0.001 linear | 1.98 (1.12–3.48) | <0.001 linear |
| AHI≥ 15 | 11/29 (37.9) | 6.96 (2.99–16.19) | 0.58 quadratic | 4.27 (1.74–10.45) | 0.30 quadratic |
Abbreviations: AHI=apnea-hypopnea index; 95% CI=95% confidence interval; BMI=body mass index
Early and mid- pregnancy AHI results were adjusted for maternal age (≤21, 22–35, and >35), BMI (<25, 25 to <30, ≥30) and chronic hypertension (yes, no) as determined in early pregnancy. The mid-pregnancy results were also adjusted for rate of weight gain from early pregnancy to mid-pregnancy (as a continuous variable, linear on the log odds scale). The adequacy of a linear term for rate of weight gain was investigated using AHI (dichotomized: <5, ≥5), BMI categories, linear rate of change in weight, and quadratic rate of change in the model. The quadratic term was not significant and was not considered further. The adjusted analyses for early and mid- pregnancy included Ne=3,093 and Nm=2,413 observations, respectively. P-values from logistic regression are given for general association with AHI categories. For a significant test of general association with the 4-category AHI, post-hoc tests are given for linear and quadratic trends in the log odds across AHI categories using orthogonal contrasts.
Preeclampsia includes mild, severe, and superimposed preeclampsia and eclampsia. Hypertensive disorder of pregnancy includes mild, severe, and superimposed preeclampsia and eclampsia, plus antepartum gestational hypertension.