Table 2.

Associations Between Caffeine Consumption and Livebirth Among 2474 Couples Undergoing In Vitro Fertilization

	No. of cycles with livebirth	No. of cycles without livebirth	Unadjusted OR (95% CI)	Adjusted OR (95% CI)
Female
No caffeine	253	734	1.00 (referent)	1.00 (referent)
>0–800 mg/week	477	1395	0.99 (0.83, 1.18)	1.00 (0.83, 1.21)
>800–1400 mg/week	191	700	0.80 (0.64, 0.99)	0.89 (0.71, 1.12)
>1400 mg/week	226	740	0.88 (0.72, 1.09)	1.07 (0.85, 1.34)
p-value, test for linear trend			0.08	0.74
Male
No caffeine	96	281	1.00 (referent)	1.00 (referent)
>0–1400 mg/week	617	1769	1.02 (0.80, 1.31)	1.03 (0.80, 1.34)
>1400–2100 mg/week	215	722	0.88 (0.66, 1.16)	0.96 (0.72, 1.29)
>2100 mg/week	219	797	0.81 (0.62, 1.07)	0.93 (0.70, 1.24)
p-value, test for linear trend			0.007	0.27
Couple
Female ≤800 mg/week and male ≤140 mg/week	499	1359	1.00 (referent)	1.00 (referent)
Only female >800 mg/week	214	691	0.85 (0.71, 1.02)	0.97 (0.80, 1.18)
Only male >1400 mg/week	231	770	0.83 (0.69, 0.99)	0.91 (0.76, 1.10)
Female >800 mg/week and male >140 mg/week	203	749	0.74 (0.62, 0.90)	0.91 (0.75, 1.11)

Odds ratio (OR) and 95% confidence interval (CI) are from discrete survival analysis (Cox proportional odds model). Adjusted models included female age (<35, 35–37, 38–40, >40 years), body mass index (<19, 19–24.9, 25–29.9, ≥30 kg/m²), clinic site (1, 2, 3), study enrollment period (1994–1998 vs. 1999–2003), female tobacco use (0, 1–6, 7–60 cigarettes/week), female alcohol use (0, >0–38, >38 g/week), and primary infertility diagnosis. p-values, tests for linear trend, are calculated from the Wald statistic and are two-sided.