Table 1.
Characteristics of the study population (N = 450 women) undergoing their first recorded fresh IVF or ICSI cycle
| Covariate | Pregnancy N = 300 | Non-pregnancy N = 150 | P |
|---|---|---|---|
| Age at first cyclea | 31.0 (29.0, 33.0) | 31.0 (29.0, 34.0) | 0.123c |
| BMI before transfer, kg/m2, No. (%) | |||
| < 18.5 | 19 (6.3) | 9 (6.0) | 0.954e |
| 18.5 ≤ BMI < 24 | 210 (70.0) | 102 (68.0) | |
| 24 ≤ BMI < 28 | 58 (19.3) | 32 (21.3) | |
| BMI ≥ 28 | 13 (4.3) | 7 (4.7) | |
| Annual Household Income, 10,000 CNY, No. (%) | |||
| < 5 | 12 (4.0) | 7 (4.7) | 0.423e |
| 5 ~ 10 | 77 (25.7) | 48 (32.0) | |
| 10 ~ 20 | 118 (39.3) | 49 (32.7) | |
| > 20 | 93 (31.0) | 46 (30.7) | |
| Occupation (%) | |||
| Mental worker | 150 (50.0) | 73 (48.7) | 0.831d |
| Physical worker | 135 (45.0) | 71 (47.3) | |
| No | 15 (5.0) | 6 (4.0) | |
| Education, year, No. (%) | |||
| ≥ 12 | 218 (72.7) | 103 (68.7) | 0.439d |
| < 12 | 82 (27.3) | 47 (31.3) | |
| Prior history of pregnancy loss (%) | |||
| Gravid, with no prior history of loss | 12 (4.0) | 8 (5.3) | 0.508e |
| Gravid, with prior history of loss | 14 (4.7) | 10 (6.7) | |
| Nulliparous | 274 (91.3) | 132 (88.0) | |
| Sleep quality (%)b | |||
| Good | 228 (77.6) | 124 (85.5) | 0.065d |
| Poor | 66 (22.4) | 21 (14.5) | |
| Infertility factor (%) | |||
| Couple’s factor | 181 (60.3) | 99 (66.0) | 0.399e |
| Female factor | 98 (32.7) | 46 (30.7) | |
| Male factor | 19 (6.3) | 5 (3.3) | |
| Unexplained factor | 2 (0.7) | 0 (0.0) | |
| Duration of infertility (m) | 36.0 (24.0, 53.0) | 36.0 (24.0, 60.0) | 0.683c |
| Smoking before transfer, No. (%) | |||
| Non-smoker | 297 (99.0) | 147 (98.0) | 0.405e |
| Smoker | 3 (1.0) | 3 (2.0) | |
| Alcohol use before transfer, No. (%) | |||
| Rarely | 292 (97.3) | 148 (98.7) | 0.507e |
| Regular | 8 (2.7) | 2 (1.3) | |
| Exercise, No. (%) | |||
| Rarely | 249 (83.0) | 124 (82.7) | 1.000d |
| Regular | 51 (17.0) | 26 (17.3) | |
Values are number of women (%) for categorical variables, median and range for continuous variables unless indicated otherwise
aCases and controls were matched on female age
bVariable contains missing data
cP values were derived with Mann–Whitney U test for nonnormally distributed continuous variables
dP values were derived with Pearson chi-square test for categorical variables
eP values were derived with Fisher exact test for categorical variables with less than 10 observations per category