Table I.
Distribution of maternal and pregnancy characteristics within the two study samples, all conceptions (n= 189) and clinical pregnancies only (n= 142).
| Number of conceptionsa (%) | Number of clinical pregnanciesb (%) | |
|---|---|---|
| Time from ovulation to implantation | ||
| ≥10 days | 87 (46) | 52 (37) |
| ≤9 days | 102 (54) | 89 (63) |
| Age | ||
| ≥29 | 97 (51) | 72 (51) |
| <29 | 92 (49) | 70 (49) |
| Prior pregnancy | ||
| Yes | 128 (68) | 94 (66) |
| No | 60 (32) | 48 (34) |
| History of miscarriage | ||
| Yes | 27 (14) | 18 (13) |
| No | 101 (54) | 76 (53) |
| Never pregnant | 60 (32) | 48 (34) |
| Age at menarche | ||
| <12 | 24 (13) | 20 (14) |
| 12, 13 | 114 (60) | 83 (58) |
| >13 | 51 (27) | 39 (28) |
| Cycle length | ||
| <29 | 86 (48) | 66 (49) |
| ≥29 | 95 (52) | 69 (51) |
| Regular cycles | ||
| Yes | 162 (86) | 120 (84) |
| No | 27 (14) | 22 (16) |
| Recent oral contraceptive use | ||
| Yes | 17 (9) | 12 (9) |
| No | 172 (91) | 130 (91) |
| Oocyte-waiting time | ||
| Long | 23 (12) | 11 (8) |
| Short or average | 166 (88) | 130 (92) |
| BMI | ||
| <18 | 18 (10) | 14 (10) |
| 18 to <25 | 155 (82) | 115 (82) |
| ≥25 | 16 (8) | 13 (9) |
| Prenatal DES exposure | ||
| Yes | 7 (5) | 4 (4) |
| No | 135 (95) | 100 (96) |
| Prenatal exposure to maternal smoking | ||
| Yes | 47 (28) | 36 (29) |
| No | 118 (72) | 88 (71) |
| Number of smokers in the home when participant was <10 years old | ||
| 0 | 64 (35) | 44 (31) |
| 1 | 64 (35) | 49 (36) |
| ≥2 | 56 (30) | 46 (33) |
| Husband's current smoking | ||
| Yes | 15 (8) | 12 (9) |
| No | 174 (92) | 130 (91) |
| Smoking status at enrollment | ||
| Current | 11 (6) | 8 (6) |
| Former | 52 (27) | 40 (28) |
| Never | 126 (67) | 94 (66) |
| Alcohol intake | ||
| Any | 150 (79) | 114 (80) |
| None | 39 (21) | 28 (20) |
| Caffeine intake | ||
| Any | 179 (95) | 133 (94) |
| None | 10 (5) | 9 (6) |
| Marijuana use | ||
| Any | 26 (14) | 20 (14) |
| None | 163 (86) | 122 (86) |
| Vitamin use | ||
| Yes | 99 (53) | 79 (55) |
| No | 89 (47) | 63 (45) |
aThis sample includes early pregnancy losses and clinical pregnancies, women could have experienced either or both leading to more than one observation per woman.
bThis sample includes pregnancies that survived to clinical recognition. Women only contributed one clinical pregnancy leading to only one observation per woman.