TABLE 1.
Results of the linear regressions predicting the natural log of follicular phase length, with fitted values presented in days.a
| Variable | n (%) (N=217) | Geometric Mean | p-valueb |
|---|---|---|---|
| Physical and Lifestyle factors | |||
| Age | |||
| <27 | 49 (24.4) | 15.4 | 0.52 |
| 27–31 | 110 (54.7) | 15.4 | |
| >31 | 42 (20.9) | 14.5 | |
| Height (in meters) | |||
| <1.63 | 43 (21.4) | 15.5 | 1 |
| 1.63–1.68 | 106 (52.7) | 15.4 | |
| >1.68 | 52 (25.9) | 15.4 | |
| BMI | |||
| Underweight | 20 (9.9) | 15.2 | 0.91 |
| Normal | 159 (79.1) | 15.4 | |
| Overweight | 22 (10.9) | 15.9 | |
| Marijuana use | |||
| None | 172 (85.6) | 15.1 | 0.04 |
| Low | 14 (7.0) | 18.6 | |
| High | 15 (7.5) | 16.8 | |
| Tobacco smoking | |||
| Current | 12 (6.0) | 15.1 | 0.98 |
| Former | 49 (24.4) | 15.4 | |
| Never | 140 (69.6) | 15.4 | |
| Alcohol intake (servings/month)c | |||
| <=1 | 51 (25.4) | 14.4 | 0.19 |
| >1–18 | 102 (50.7) | 15.7 | |
| >18 | 48 (23.9) | 16.1 | |
| Caffeine intake (mg/week)d | |||
| <=1480 | 58 (28.9) | 14.6 | 0.2 |
| >1480–<6900 | 102 (50.7) | 15.4 | |
| >=6900 | 41 (20.4) | 16.5 | |
| Reproductive factors | |||
| Recente Oral Contraceptive Use | |||
| Yes | 29 (14.4) | 17.7 | 0.04 |
| No | 172 (85.6) | 15.4 | |
| Duration of pill use | |||
| Never | 26 (13.0) | 13.9 | 0.0003 |
| >0–1 | 44 (22.0) | 13.2 | |
| >1–2 | 28 (14.0) | 15.7 | |
| >2–4 | 41 (20.5) | 16.3 | |
| >4 | 61 (30.5) | 17.3 | |
| Missing | 1 | ||
| Duration of IUD use | |||
| Never | 141 (70.1) | 15.4 | 0.09 |
| >0–1 | 25 (12.4) | 15.8 | |
| >1–2 | 10 (5.0) | 14.8 | |
| >2–4 | 9 (4.5) | 12.7 | |
| >4 | 16 (8.0) | 18.4 | |
| Age at menarche | |||
| <12 | 32 (15.9) | 15.0 | 0.83 |
| 12,13 | 117 (58.2) | 15.4 | |
| >13 | 52 (25.9) | 15.7 | |
| Frequency of Intercourse (per week) | |||
| ≤1 | 39 (19.4) | 15.3 | 0.13 |
| >1–2 | 45 (22.4) | 14.6 | |
| >2–3 | 78 (38.8) | 16.5 | |
| >3 | 39 (19.4) | 14.6 | |
| Gravidity | |||
| 0 | 70 (35.0) | 15.5 | 0.73 |
| 1,2 | 110 (55.0) | 15.5 | |
| ≥3 | 20 (10.0) | 14.6 | |
| Missing | 1 | ||
| History of Miscarriage (among gravid women) | |||
| Yes | 28 (14.0) | 14.0 | 0.04 |
| No | 102 (51.0) | 16.2 | |
| Never pregnant | 70 (35.0) | ||
| Missing | 1 | ||
| Prenatal Exposures | |||
| DES | |||
| Yes | 7 (4.8) | 14.1 | 0.42 |
| No | 139 (95.2) | 15.6 | |
| Missing | 55 | ||
| In utero smoke exposure | |||
| No | 111 (65.3) | 15.4 | 0.29 |
| Yes | 59 (34.7) | 16.2 | |
| Missing | 31 | ||
a
Each variable is adjusted for age and recent pill use. Predicted mean cycle lengths are presented for a woman age 27–31 and a non-recent pill user.
b
p-value testing the null hypothesis that the groups share a common mean, the alternative is that at least one group is different.
c
A ”serving” was defined as 12 ounces of beer, 4 ounces of wine or 1.5 ounces of hard liquor.
d
100mg is approximately the amount of caffeine in one cup of brewed coffee
e
Within 90 days of cycle start.