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. 2010 Sep 15;92(5):1120–1132. doi: 10.3945/ajcn.2010.29789

TABLE 2.

Case-control studies of caffeine consumption and risk of preterm birth1

Author, publication year, and country No. of cases/no. of controls Intake measurement Trimester considered Preterm definition Comparisons made by authors Risk estimate (95% CI) Comparisons made in meta-analysis Adjusted confounders
Chiaffarino et al, 2006, Italy (42) 502/1966 Coffee, tea, and cola (cups or glasses/d) Third and throughout pregnancy 28–37 wk gestation 0 cups/d 1.0 0 mg/d Age, education, parity, smoking during the first trimester of pregnancy, gestational hypertension, and history of preterm births
1 cup (90 mg)/d 0.9 (0.6, 1.2)
≥2 cups/d 0.9 (0.7, 1.3) ≥150 mg/d
de Souza and Sichieri, 2005, Brazil (45) 140/162 Coffee, tea, maté, and powdered chocolate (servings in mL or g); authors computed daily caffeine intake (mg/d) Throughout pregnancy <37 wk of gestation <50 mg/d 1.00 <50 mg/d NA
50–99 mg/d 1.58 (0.88, 2.84)
≥100 mg/d 1.35 (0.48, 3.80) ≥100 mg/d
Tough et al, 2003, Canada (47) 323/664 Coffee Throughout pregnancy Live born singleton infant at <37 wk of gestation <1 cup/d 1.0 <100 mg/d Prior conception experiences, emotional health, interpregnancy intervals, pregnancy complications, maternal complications during pregnancy
1.38 (1.01, 1.88) ≥100 mg/d
Caffeinated soft drinks ≥1 cup/d 1.0 <27 mg/d
1.22 (0.89, 1.72) ≥27 mg/d
Bicalho and Filho, 2002, Brazil (46) 182/354 Coffee, soft drinks, and tea (servings in mL); authors computed daily caffeine intake (mg/d) Throughout pregnancy Delivery before 37 wk gestation 0 mg/d 1.0 0 mg/d Mother's age, schooling, income, marital status, skin color, parity, smoking, previous low-birth-weight children, mother's prepregnancy weight, employment status, interval between pregnancies, prenatal care, and high blood pressure
<300 mg/d 0.59 (0.32, 1.09)
≥300mg/d 0.32 (0.15, 0.72) ≥300 mg/d
Pastore and Savitz 1995, USA (43) 408/490 Caffeinated coffee, tea, cola soft drinks, and non-cola caffeinated soft drinks (servings and preparation method); authors computed daily caffeine intake (mg/d) Second and third <37 wk of gestation Second trimester: 0 mg/d >1 mg/d
Third trimester: 0 mg/d >1 mg/d
Second trimester: 1.0 1.5 (1.0, 2.3)
Third trimester: 1.0 0.8 (0.6, 1.2)
Second trimester: 0 mg/d >1 mg/d
Third trimester: 0 mg/d >1 mg/d
None
Williams et al, 1992, USA (44) 488/2252 Coffee (cups/d) First Delivery before 37 wk gestation without premature rupture of membranes 0 cups/d 1.0 0 mg/d Race, education, maternal age, welfare status, marijuana and alcohol use during pregnancy, parity, previous spontaneous or induced abortion, cervical incompetence, bleeding during pregnancy, prepregnancy BMI, and cigarette smoking
1–2 cups/d 1.0 (0.8, 1.3)
3 cups/d 1.4 (0.9, 2.3)
4 cups/d 1.8 (0.9, 3.4)
≥5 cups/d 1.1 (0.5, 2.1) >400 mg/d
Berkowitz et al, 1982, USA (26) 166/299 Coffee and tea, including iced coffee and iced tea, separately (cups/d) First Singleton live birth before 37 wkof gestation not preceded by spontaneous labor or rupture of membranes 0 cups/d 1.0 0 mg/d Race, socioeconomic status, infertility history, first trimester spotting or light bleeding, pregravid weight, maternal weight gain, previous induced abortion, leisure-time physical activity, and attitude toward pregnancy
1 cup/d 0.7 (0.4, 1.3)
2 cups/d 0.9 (0.5, 1.6)
3 cups/d 1.6 (0.8, 3.3)
≥4 cups/d 0.6 (0.3, 1.4) ≥320 mg/d
Second 0 cups/d 1.0 0 mg/d
1 cup/d 0.6 (0.4, 1.1)
2 cups/d 0.8 (0.4, 1.4)
3 cups/d 1.3 (0.7, 2.8)
≥4 cups/d 0.6 (0.3, 1.3) ≥320 mg/d
Third 0 cups/d 1.0 0 mg/d
1 cup/d 0.6 (0.4, 1.1)
2 cups/d 1.1 (0.6, 2.0)
3 cups/d 1.5 (0.7, 3.0)
≥4 cups/d 0.5 (0.2, 1.1) ≥320 mg/d
1

NA, not available.