Table 1

Baseline characteristics* of 473 women in the Environment and Reproductive Health (EARTH) Study by frequency of lifting heavy objects at work

 Total cohortLifting heavy objects at work
(n=473)Never (n=283)Sometimes/often (n=190)p Value†
Baseline characteristics
 Age, years35.0 (32.0–38.0)35.0 (32.0–38.0)35.0 (32.0–38.0)0.56
Race/ethnic group, n (%)0.32
 White/Caucasian400 (84.6)239 (84.4)161 (84.7)
 Black8 (1.7)3 (1.1)5 (2.6)
 Asian44 (9.3)30 (10.6)14 (7.4)
 Other21 (4.4)11 (3.9)10 (5.3)
 Body Mass Index, kg/m223.2 (21.2–26.2)23.2 (21.0–26.2)23.2 (21.3–26.2)0.63
Smoking status, n‡ (%)0.77
 Never smoked345 (73.1)208 (73.8)137 (72.1)
 Former smoker115 (24.4)68 (24.1)47 (24.7)
 Current smoker12 (2.5)6 (2.1)6 (3.2)
Education, n (%)0.001
 <College graduate39 (8.3)17 (6.0)22 (11.6)
 College graduate153 (32.4)79 (27.9)74 (39.0)
 Graduate degree281 (59.4)187 (66.1)94 (49.5)
 Total physical activity (hour/week)5.4 (2.7–9.5)5.0 (2.7–9.2)6.2 (2.7–10.5)0.23
Reproductive characteristics, n (%)
 History of ever been pregnant188 (39.8)107 (37.8)81 (42.6)0.29
 History of been treated for infertility226 (47.8)137 (48.4)89 (46.8)0.74
 Previous infertility examination379 (80.1)230 (81.3)149 (78.4)0.45
Initial infertility diagnosis0.53
 Male factor124 (26.2)70 (24.7)54 (28.4)
 Female factor141 (29.8)78 (27.6)63 (33.2)
  Diminished ovarian reserve46 (9.7)23 (8.1)23 (12.1)
  Endometriosis26 (5.5)15 (5.3)11 (5.8)
  Ovulation disorders35 (7.4)21 (7.4)14 (7.4)
  Tubal25 (5.3)14 (5.0)11 (5.8)
  Uterine9 (1.9)5 (1.8)4 (2.1)
 Unexplained208 (44.0)135 (47.7)73 (38.4)
  • *Values are presented as median (IQR) unless otherwise noted.

  • †From Kruskal-Wallis test for continuous variables and χ2 tests (or Fisher's exact test where appropriate) for categorical variables.

  • ‡This variable has 1 missing.

  • GnRH, gonadotropin-releasing hormone.