Table 2:
Association of weight change with hypertensive disorders of pregnancy, with weight change standardized to Institute of Medicine trimester-specific guidelines based on pre-pregnancy body mass index
| Variable | Hypertensive disorder of pregnancy (N = 1,564) | No Hypertensive disorder of pregnancy (N = 6,732) | P valuea | Unadjusted incidence rate ratio | 95 % confidence interval | Adjusted incidence rate ratiob | 95% confidence interval |
|---|---|---|---|---|---|---|---|
| Early weight change (IOM category): | 0.004 | ||||||
| Inadequate | 417 (26.7) | 2,030 (30.2) | 0.93 | 0.81 – 1.07 | 0.89 | 0.77 – 1.03 | |
| Adequate | 358 (22.9) | 1,600 (23.8) | (ref) | (ref) | |||
| Excessive | 789 (50.5) | 3,102 (46.1) | 1.11 | 0.98 – 1.26 | 0.95 | 0.83 – 1.08 | |
| Mid weight change (IOM category): | < 0.001 | ||||||
| Inadequate | 587 (37.5) | 2,794 (41.5) | 1.06 | 0.91 – 1.23 | 1.03 | 0.89 – 1.21 | |
| Adequate | 243 (15.5) | 1,244 (18.5) | (ref) | (ref) | |||
| Excessive | 734 (46.9) | 2,694 (40.0) | 1.31 | 1.13 – 1.51 | 1.16 | 1.01 – 1.35 | |
| Late weight change (IOM category): | < 0.001 | ||||||
| Inadequate | 184 (11.8) | 1,091 (16.2) | 0.94 | 0.77 – 1.16 | 0.80 | 0.64 – 0.99 | |
| Adequate | 177 (11.3) | 979 (14.5) | (ref) | (ref) | |||
| Excessive | 1,203 (76.9) | 4,662 (69.3) | 1.34 | 1.14 – 1.57 | 1.20 | 1.02 – 1.40 |
P value for t tests for continuous variables, chi square tests for categorical variables.
In addition to the factors listed here, multivariable models also adjusted for maternal BMI at first visit, maternal age at first visit, maternal race, maternal education, insurance status, gravidity, smoking within 3 months of pregnancy, and maternal diabetes, all of which were significant at the p < 0.10 level with either weight gain or hypertensive disorders in bivariable analyses, but not in multivariable analyses. These incidence rate ratios also account for fixed effects by study site and subsite.