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 |
NA, not available.