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. Author manuscript; available in PMC: 2008 Oct 1.
Published in final edited form as: Environ Res. 2007 Jan 19;105(2):247–255. doi: 10.1016/j.envres.2006.11.010

TABLE 2.

Characteristics of 1344 pregnancies occurring after July 1, 1973 that ended in spontaneous abortion or live birth.

Livebirth
(n=1148)
SA
(n=196)
Chi Square
p value
Unadjusted
OR

Pregnancies N (%) N (%)
Maternal age at conception (years)
 < 20 122 (11%) 19 (10%) 0.001 Ref
 20 – 29 801 (70%) 123 (63%) 0.99 (0.59-1.66)
 30 - 34 182 (16%) 34 (17%) 1.20 (0.65-2.20)
 ≥ 35 43 (4%) 20 (10%) 2.99 (1.46-6.12)
Maternal PBB at conception (ppb) a
 <1 625 (54%) 116 (59%) 0.21 Ref
 1 – 2.9 221 (19%) 40 (20%) 0.98 (0.66-1.44)
 > 2.9 302 (26%) 40 (20%) 0.71 (0.49-1.05)
PCB exposure (ppb) a
 <5 481 (42%) 85 (43%) 0.45 Ref
 5-6.5 291 (25%) 54 (28%) 1.05 (0.73-1.52)
 >6.5 303 (26%) 50 (26%) 0.93 (0.64-1.36)
 Not measured 73 (6%) 7 (4%) 0.54 (0.24-1.22)
Time to pregnancy
 < 12 months 819 (87%) 133 (86%) 0.75 Ref
 ≥ 12 months 125 (13%) 22 (14%) 1.08 (0.67-1.77)
Prior spontaneous abortion b
 No 935 (81%) 126 (64%) <0.0001 Ref
 Yes 213 (19%) 70(36%) 2.44 (1.76-3.39)
Number of prior pregnancies b
 0 336 (29%) 38 (19%) 0.0001 Ref
 1 356 (31%) 52 (27%) 1.29 (0.83-2.01)
 2 231 (20%) 41 (21%) 1.57 (0.98-2.52)
 ≥ 3 225 (20%) 65 (33%) 2.55 (1.65-3.94)
History of infertility b
 No 950 (83%) 144 (73%) 0.002 Ref
 Yes 198 (17%) 52 (27%) 1.73 (1.22-2.46)
Thyroid problem b
 No 1046 (86%) 171 (14%) 0.03 Ref
 Yes 63 (77%) 19 (23%) 1.79 (1.05-3.06)
Uterine fibroid b
 No 1126 (98%) 192 (98%) 0.84 Ref
 Yes 21(2%) 4 (2%) 1.12 (0.38-3.29)
Endometriosis b
 No 1099 (96%) 187 (95%) 0.84 Ref
 Yes 49 (4%) 9 (5%) 1.08 (0.52-2.23)
PID prior to pregnancy b
 No 1123 (98%) 187 (96%) 0.05 Ref
 Yes 21 (2%) 8 (4%) 2.29 (1.00-5.24)
Maternal smoking during year prior to
pregnancy
 No 905 (79%) 146 (74%) 0.15 Ref
 Yes 240 (21%) 50 (26%) 1.29 (0.91-1.84)
First trimester maternal alcohol
consumption
 No 998 (87%) 165 (86%) 0.68 Ref
 Yes 143 (13%) 26 (14%) 1.10 (0.70-1.72)

Abbreviations: OR, odds ratio, PBB, polybrominated biphenyls; PCB polychlorinated biphenyls; pbb, parts per billion, PID, pelvic inflammatory disease.

a

PBB and PCB cut-points are based on the limit of detection and the median exposure of spontaneous abortions above the level of detection.

b

Prior to the index pregnancy

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