Table 3.

Prenatal/neonatal factors and the risk of PD in the Nurses’ Health Study

Variable	# Participants*	# Cases*	Age-adjusted Rate Ratio and 95% CI		Multivariate-adjusted† Rate Ratio and 95% CI
Maternal age at birth
14–19	7038	11	0.59	0.32, 1.10	0.61	0.32, 1.13
20–24	32892	95	1.16	0.90, 1.54	1.18	0.88, 1.57
25–29	36858	91	1.0 (ref)		1.0 (ref)
30–34	24669	72	1.17	0.89, 1.59	1.16	0.85, 1.58
35–49	17173	50	1.12	0.79, 1.58	1.13	0.80, 1.60
			test for linear trend	P=0.41‡	test for linear trend	P=0.46‡
Paternal age at birth
14–19	1430	1	0.25	0.04, 1.84	0.25	0.03, 1.81
20–24	16680	44	1.06	0.73, 1.52	1.07	0.74, 1.54
25–29	33973	85	1.0 (ref)		1.0 (ref)
30–34	29526	78	1.06	0.78, 1.44	1.05	0.77, 1.43
35–39	17903	53	1.18	0.84, 1.66	1.17	0.83, 1.65
40+	14003	43	1.13	0.78, 1.63	1.12	0.78, 1.62
			test for linear trend	P=0.52‡	test for linear trend	P=0.58‡
2+ weeks premature
Yes	3903	10	0.90	0.48, 1.68	0.89	0.47, 1.67
No	81926	268	1.0 (ref)		1.0 (ref)
Multiple birth
Yes	1380	5	1.39	0.57, 3.38	1.24	0.51, 3.00
No	120180	323	1.0 (ref)		1.0 (ref)
Breastfed
No	26279	57	0.90	0.67, 1.22	0.92	0.68, 1.25
Yes	47784	181	1.0 (ref)		1.0 (ref)

^*For each factor, the number of cases and participants may not add up to the total number in the study due to missing values

^†Controlling for age in months, calendar year, pack years of smoking, family history of PD, PMH use, quintile of caffeine consumption, and the interaction between PMH use and caffeine consumption

^‡No significant non-linear trend observed