Table 3.

Subgroups analyses of the effect of WWI on infertility.

Subgroups	N		OR (95%CI), P-value	P for interaction
	Total	Infertility
Age				0.009
Tertile 1	1090	49	1.78 (1.28, 2.49) <0.001
Tertile 2	1181	122	1.72 (1.36, 2.17), <0.001
Tertile 3	1255	193	1.16 (0.96, 1.42), 0.129
Race				0.9406
Mexican American	618	61	1.66 (1.14, 2.41), 0.007
Other Hispanic	369	30	1.45 (0.89, 2.38), 0.136
Non-Hispanic White	1146	141	1.52 (1.22, 1.89), <0.001
Non-Hispanic Black	776	75	1.38 (1.05, 1.81), 0.023
Other Race - Including Multi-Racial	617	57	1.40 (0.95, 2.06), 0.088
Education lever				0.1717
Less than 9th grade	159	13	0.88 (0.43, 1.82), 0.731
9-11th grade	333	38	2.30 (1.44, 3.66), <0.001
High school graduate/GED or equivalent	605	71	1.38 (1.01, 1.88), 0.044
Some college or AA degree	1179	139	1.34 (1.07, 1.67), 0.009
College graduate or above	863	103	1.49 (1.12, 1.99), 0.006
Marital status				0.5127
Married or living with partner	1369	267	1.36 (1.13, 1.63), 0.001
Living alone	1770	97	1.49 (1.21, 1.83), <0.001
Smoked at least 100 cigarettes				0.8891
Yes	944	131	1.42 (1.14, 1.78), 0.002
No	2582	233	1.45 (1.22, 1.72), <0.001
Had at least 12 alcohol drinks/1 year				0.2265
Yes	2467	272	1.55 (1.32, 1.81), <0.001
No	1059	92	1.27 (0.96, 1.68), 0.088
Had regular periods in past 12 months				0.9038
Yes	3179	326	1.46 (1.27, 1.69), <0.001
No	347	38	1.42 (0.93, 2.17), 0.100
Age when first menstrual period occurred				0.2797
Age<10	162	28	1.19 (0.74, 1.83), 0.4701
10≤Age<15	2904	289	1.40 (1.20, 1.64), <0.001
15≤Age ≤ 20	460	47	1.86 (1.28, 2.69), 0.001

Subgroup analysis for the association between WWI and infertility. None of the stratifications including race, Education lever, Marital status, smoked at least 100 cigarettes, had at least 12 alcohol drinks/1 year and had regular periods in past 12 months affected the positive association of WWI and infertility.