. 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 3.

Unadjusted and adjusted probability of spontaneous abortion among pregnancies occurring after July 1, 1973.

	Unadjusted GEE^a n=1344		Adjusted GEE ^a n=1344		Adjusted Logistic ^b n=529
	OR	95% CI	OR	95% CI	OR	95% CI
PBB (ppb)^c
< 1	Ref		Ref		Ref
1–2.9	1.07	0.69-1.66	1.05	0.67-1.63	0.51	0.24-1.11
> 2.9	0.69	0.45-1.07	0.73	0.47-1.13	0.67	0.33-1.33
PCB (ppb)
≤ 5	Ref		Ref		Ref
> 5 – 6.5	1.06	0.68-1.64	0.97	0.62-1.52	1.14	0.57-2.26
> 6.5	0.88	0.57-1.36	0.91	0.59-1.41	1.15	0.56-2.36
Not measured	0.50	0.20-1.27	0.48	0.19-1.26	0.76	0.21-2.78
Maternal age at conception (years)
< 20	Ref		Ref		Ref
20 – 29	0.96	0.56-1.64	0.94	0.55-1.61	0.60	0.30-1.21
30 - 34	1.13	0.62-2.06	1.07	0.57-2.01	1.22	0.45-3.31
≥ 35	2.76	1.22-6.27	2.46	1.10-5.49	2.11	0.70-6.36
Age at Menarche
≤ 11	Ref		Ref		Ref
12- 13	0.52	0.34-0.80	0.58	0.38-0.89	0.30	0.16-0.57
≥ 14	0.53	0.32-0.87	0.55	0.34-0.91	0.37	0.17-0.81
Prior Infertility^d
No	Ref		Ref		Ref
Yes	1.68	1.11-2.54	1.52	0.98-2.38	1.74	0.92-3.30

Abbreviations: GEE, generalized estimating equation, OR, odds ratio; CI, confidence interval; PBB, polybrominated biphenyls; PCB polychlorinated biphenyls; pbb, parts per billion.

Generalized estimating equations were used to account for the dependency between pregnancies of the same woman. Adjusts for all covariates in table.

The adjusted Logistic Model includes only the first pregnancy after July 1, 1973 for each woman and controls for all of the covariates listed in the table.

PBB at the time of conception as determined by the decay model.

Prior to index pregnancy