Table III.
Change in BMI, height, waist circumference, waist-to-hip ratio and the incidence of laparoscopically confirmed endometriosis in the Nurse's Health Study cohort, 1989–2011a.
| All women |
Infertileb |
Not infertileb |
Pheterogeneityc | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| No. of cases | No. of p-yrs | RR | 95% CI | No. of cases | No. of p-yrs | RR | 95% CI | No. of cases | No. of p-yrs | RR | 95% CI | ||
| Change in BMI (kg/m2) | |||||||||||||
| <−1 | 310 | 76625 | 0.94 | (0.82–1.07) | 67 | 4534 | 0.78 | (0.59–1.03) | 239 | 70924 | 0.98 | (0.85–1.14) | <0.0001 |
| −1 to 1 | 795 | 199176 | 1.00 | Referent | 200 | 11509 | 1.00 | Referent | 585 | 184210 | 1.00 | Referent | |
| >+1 to 6 | 2469 | 613706 | 1.09 | (1.01–1.18) | 584 | 34371 | 1.02 | (0.87–1.21) | 1851 | 565573 | 1.10 | (1.00–1.21) | |
| >+6 | 1164 | 340888 | 1.02 | (0.93–1.12) | 170 | 16960 | 0.66 | (0.53–0.82) | 971 | 311750 | 1.12 | (1.01–1.25) | |
| Ptrend | 0.69 | 0.0009 | 0.03 | ||||||||||
| Waist circumference (cm) | |||||||||||||
| 22–29.9 | 1260 | 293356 | 1.05 | (0.95–1.17) | 299 | 15343 | 1.06 | (0.84–1.34) | 951 | 272606 | 1.05 | (0.94–1.18) | 0.0002 |
| 30–32.9 | 525 | 141516 | 1.00 | Referent | 109 | 6799 | 1.00 | Referent | 408 | 132230 | 1.00 | Referent | |
| 33–37.9 | 408 | 115201 | 0.99 | (0.87–1.13) | 66 | 5445 | 0.85 | (0.61–1.17) | 342 | 107679 | 1.07 | (0.92–1.23) | |
| 38–65 | 262 | 71266 | 0.98 | (0.84–1.14) | 38 | 3797 | 0.57 | (0.39–0.84) | 221 | 66171 | 1.10 | (0.93–1.30) | |
| Ptrend | 0.19 | 0.0003 | 0.60 | ||||||||||
| Height (in) | |||||||||||||
| 40–62 | 921 | 242844 | 1.05 | (0.97–1.15) | 184 | 12949 | 1.02 | (0.84–1.24) | 702 | 220417 | 1.06 | (0.96–1.17) | 0.96 |
| 63–64 | 1303 | 352110 | 1.03 | (0.96–1.12) | 272 | 18279 | 1.07 | (0.90–1.27) | 993 | 320541 | 1.04 | (0.95–1.13) | |
| 65–66 | 1293 | 357655 | 1.00 | Referent | 273 | 18936 | 1.00 | Referent | 981 | 325793 | 1.00 | Referent | |
| 67–68 | 1057 | 242663 | 1.18 | (1.09–1.28) | 232 | 13334 | 1.22 | (1.02–1.47) | 795 | 220446 | 1.19 | (1.08–1.31) | |
| 69–85 | 418 | 102239 | 1.06 | (0.95–1.19) | 96 | 6008 | 1.06 | (0.83–1.35) | 313 | 92587 | 1.08 | (0.95–1.23) | |
| Ptrend | 0.19 | 0.43 | 0.23 | ||||||||||
| Waist/hip ratio | |||||||||||||
| <0.60 | 8 | 758 | 2.78 | (1.38–5.60) | 1 | 30 | 4.00 | (0.49–32.95) | 7 | 711 | 2.90 | (1.37–6.15) | 0.16 |
| 0.60–0.69 | 185 | 41423 | 0.99 | (0.85–1.16) | 50 | 2375 | 1.24 | (0.89–1.71) | 134 | 38269 | 0.94 | (0.79–1.13) | |
| 0.70–0.79 | 1376 | 334976 | 1.00 | Referent | 284 | 17123 | 1.00 | Referent | 1084 | 311726 | 1.00 | \Referent | |
| 0.80–0.89 | 698 | 193977 | 0.95 | (0.87–1.04) | 150 | 9307 | 1.05 | (0.85–1.30) | 539 | 181360 | 0.92 | (0.83–1.02) | |
| ≥0.90 | 178 | 47359 | 1.01 | (0.86–1.18) | 27 | 2409 | 0.73 | (0.48–1.11) | 149 | 43997 | 1.08 | (0.91–1.28) | |
| Ptrend | 0.41 | 0.13 | 0.76 | ||||||||||
aMultivariable incidence rate ratios (RR) with 95% confidence intervals (CI) calculated using time-varying Cox proportional hazards models, adjusting for parity and infertility status. Test for heterogeneity was assessed using the likelihood ratio test comparing the model with main effects only with the model with main effects and interaction terms. Number of cases among infertile and that among non-infertile women may not sum to number of cases for all women due to missing data. Total number of cases differs between exposures due to the number of women who contributed data toward a given exposure. p-yrs = person-years.
bInfertility is defined as attempting to conceive for >1 year without success. Infertility-stratified analyses are adjusted for parity.
cTest for heterogeneity comparing the effect of BMI on endometriosis risk between women with concurrent infertility and those without concurrent infertility.