Apple Women’s Health Study
The Apple Women’s Health Study is the first long-term research study of this scale and scope that aims to advance the understanding of menstrual cycles and their relationship to various health conditions.
Connecting the dots between irregular periods, polycystic ovary syndrome and endometrial cancer risk – Data
More details about the information presented in the below tables are included in the study update: Connecting the dots between irregular periods, polycystic ovary syndrome and endometrial cancer risk.
Table #1: Characteristics of the study population.
| Characteristics | Overall | |
| N | 54363 | |
| Age at enrollment, mean (SD) | 34.8 (11.3) | |
| Race/ethnicity, n (%) | ||
| Asian | 1781 (3.3) | |
| Hispanic | 3780 (7.0) | |
| Non-Hispanic Black | 2835 (5.2) | |
| Non-Hispanic White | 37624 (69.2) | |
| Other | 472 (0.9) | |
| More than one | 550 (9.5) | |
| Missing | 2721 (5.0) | |
| Gravidity category, n (%) | ||
| Gravidity = 0 | 22798 (41.9) | |
| Gravidity = 1 | 6933 (12.8) | |
| Gravidity = 2+ | 20448 (37.6) | |
| Missing | 4184 (7.7) | |
| BMI category, n (%) | ||
| Underweight | 1359 (2.5) | |
| Healthy | 17555 (32.3) | |
| Overweight | 13238 (24.4) | |
| Obese, class 1 | 8971 (16.5) | |
| Obese, class 2 | 5270 (9.7) | |
| Obese, class 3 | 4947 (9.1) | |
| Missing | 3023 (5.6) | |
| Physical activity, n (%) | ||
| None | 1756 (3.2) | |
| Light | 15341 (28.2) | |
| Moderate | 19791 (36.4) | |
| Vigorous | 13739 (25.3) | |
| Strenuous | 1761 (3.2) | |
| Missing | 1975 (3.6) |
Table 1 represents the characteristics of the AWHS participants in this study. This study included eligible AWHS participants who enrolled from November 2019 to August 2022 and completed the Medical History Survey. Gravidity is the number of times a person has reported being pregnant. These BMI categories were defined based on the adult BMI classification from the Center of Disease Control and Prevention.
Table #2. Conditions stratified by time to cycle regularity.
| Characteristics | Overall | Time to cycle regularity categories | ||||||
| Less than 1 year | 1-2 years | 3-4 years | 5+ years | After using hormones | Not yet regular | Missing | ||
| N | 54363 | 18334 | 9105 | 2784 | 2503 | 6369 | 4804 | 10464 |
| Endometrial hyperplasia, n (%) | 316 (0.6) | 92 (0.5) | 45 (0.5) | 10 (0.4) | 26 (1.0) | 51 (0.8) | 48 (1.0) | 44 (0.4) |
| Endometrial cancer, n (%) | 117 (0.2) | 32 (0.2) | 14 (0.2) | 6 (0.2) | 16 (0.6) | 11 (0.2) | 14 (0.3) | 24 (0.2) |
Table 2 represents the number and percentages of having endometrial hyperplasia or endometrial cancer, stratified by categories of time to cycle regularity.
Table #3. Associations of PCOS, time to cycle regularity, and endometrial hyperplasia/cancer.
| Exposure | Outcome | Odds ratio (95% confidence intervals) | |||
| Unadjusted model | Adjusted model 1 | Adjusted model 2 | |||
| PCOS | PCOS vs. no PCOS | Endometrial hyperplasia | 4.08 (3.22, 5.13) | 4.58 (3.60, 5.79) | 4.68 (3.68, 5.93) |
| PCOS vs. no PCOS | Endometrial cancer | 2.93 (1.93, 4.34) | 3.51 (2.30, 5.25) | 3.67 (2.39, 5.50) | |
| Time to cycle regularity | 1-2 years vs. Less than 1 year | Endometrial hyperplasia | 0.98 (0.68, 1.40) | 1.15 (0.79, 1.63) | 1.15 (0.80, 1.64) |
| 3-4 years vs. Less than 1 year | Endometrial hyperplasia | 0.72 (0.35, 1.31) | 0.85 (0.41, 1.55) | 0.83 (0.40, 1.52) | |
| 5+ years vs. Less than 1 year | Endometrial hyperplasia | 2.09 (1.32, 3.19) | 2.19 (1.39, 3.35) | 2.07 (1.30, 3.17) | |
| Regular after using hormones vs. Less than 1 year | Endometrial hyperplasia | 1.60 (1.13, 2.25) | 2.12 (1.49, 3.00) | 2.36 (1.65, 3.33) | |
| Not yet regular vs. Less than 1 year | Endometrial hyperplasia | 2.00 (1.40, 2.83) | 2.93 (2.03, 4.20) | 3.10 (2.14, 4.43) | |
| 1-2 years vs. Less than 1 year | Endometrial cancer | 0.88 (0.46, 1.62) | 1.10 (0.57, 2.02) | 1.09 (0.56, 2.01) | |
| 3-4 years vs. Less than 1 year | Endometrial cancer | 1.24 (0.47, 2.76) | 1.56 (0.59, 3.50) | 1.39 (0.51, 3.14) | |
| 5+ years vs. Less than 1 year | Endometrial cancer | 3.70 (1.98, 6.64) | 4.14 (2.20, 7.49) | 3.67 (1.93, 6.69) | |
| Regular after using hormones vs. Less than 1 year | Endometrial cancer | 0.99 (0.48, 1.90) | 1.19 (0.71, 2.89) | 1.60 (0.76, 3.12) | |
| Not yet regular vs. Less than 1 year | Endometrial cancer | 1.67 (0.86, 3.08) | 2.81 (1.43, 5.28) | 3.02 (1.53, 5.68) | |
Table 3 represents corresponding odds ratios and 95% confidence intervals for the association of PCOS or time to cycle regularity with endometrial cancer or endometrial hyperplasia. Model 1 adjusted for age at enrollment and race/ethnicity. Model 2 adjusted for age at enrollment, race/ethnicity, and number of times pregnant.
More information is in the full study update: Connecting the dots between irregular periods, polycystic ovary syndrome and endometrial cancer risk.