136
Are caffeinated
beverages risk factors for delayed conception?
The
association between time to conceive reported by 2817 fertile women who had recently had a liveborn child and consumption of coffee, tea, and "cola" drinks has been investigated. No evidence for an adverse effect of caffeine was found. For levels of consumption ranging from less than one cup of coffee per week (501 mg caffeine per month) to more than two cups of coffee per day (7000 mg per month), the average time to conceive was similar. The fecundability ratio adjusted for known risk factors for time to conceive was 1·03 (95% confidence interval 0·921·16) between those who consumed more than 7000 mg caffeine per month and those who consumed 500 mg or less per month. Furthermore caffeine consumption was not associated with infertility in 1818 infertile women and their primiparous controls.
decaffeinated coffee, and tea, and the weekly consumption of cola drinks. Other sources of caffeinated beverages (ie, caffeinated non-cola drinks) were not included in the questionnaire. Total caffeine consumption per month was calculated as: one cup of coffee contained 100 mg caffeine, tea 50 mg, and cola drinks 40 mg.1 The total caffeine consumption per month was then divided into the same five levels used by Wilcox et al.1 Fertility in relation to caffeine consumption was evaluated in four ways. The first three methods were based on the reported time to conceive the last child in the group of 2817 women: (a) the mean time to conceive was computed for women consuming different amounts of caffeine; (b) a fecundability ratio was computed for conception rates, month by month, and (c) a fecundability ratio (risk ratio) based on a proportional hazards model was computed to examine the independent effects of several factors.6 The fourth method was based on case-control comparisons of caffeine
consumption between women with primary infertility (cases) and primiparous controls.
Results The
Introduction Women who consume more than 3150 mg caffeine per month, the equivalent of one cup of coffee per day, have been reported to have conception rates 50% lower than women who consume less caffeine.1 We have studied the relation between fertility and the consumption of caffeinated and related beverages and other factors among women without a history of infertility and among women with
figure shows the distribution of the reported time to conceive by the 2817 women with a planned pregnancy. The median time was 2-0 months and the mean was 4-5 months; 6% of the women reported that it took longer than 12 months to conceive. .9 -
primary infertility. Patients and methods study groups were 2817 women without a history of infertility who, between April, 1981, and September, 1983, delivered a livebom child as a result of a planned pregnancy at one of seven institutions in the USA and Canada (Brigham and Women’s Hospital, New England Fertility and Gynaecology Associates, the University of Vermont, the University of Colorado, the University of Kentucky, the University de Sherbrooke, and George Washington University), and 1818 infertile women, who between January, 1981, and June, 1983, presented to the same institutions with primary infertility.2 Both groups were interviewed with the same questionnaire, which contained questions on sociodemographic factors, menstrual, reproductive, and general medical history, sexual activity, contraceptive use, cigarette, marijuana, and cocaine use, the consumption of alcohol, coffee, tea, and "cola" soft drinks, and on other habits. Information was retrospectively collected on time to conceive, cigarette smoking, and consumption of alcohol, coffee, tea, and cola drinks. Our main aim had been to investigate the relation between use of intrauterine devices and infertility but data were collected to study other determinants of fertility. The relation between infertility and contraceptive use and cigarette smoking has been reported.2-5 The variables relating to caffeine consumption included in these analyses were: the reported average daily consumption of ordinary coffee, The
Distribution of reported time to conception in 2817 women with a
planned
pregnancy.
For each type of caffeinated beverage except tea the time taken to conceive was unrelated to increasing levels of consumption (table 1). The monthly probability of conception for women consuming more than 3150 mg ADDRESSES: Division of Sexually Transmitted Diseases, Center for Prevention Services, Centers for Disease Control, Public Health Service, US Department of Health and Human Services, Atlanta, Georgia (M R. Joesoef, MD, V. Beral, MRCP, R. T. Rolfs, MD, S. O. Aral, PhD) and Department of Obstetrics and Gynecology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, USA (P. W. Cramer, MD, ScD). Correspondence to Dr M. R Joesoef, Division of Sexually Transmitted Diseases, Center for Prevention Services, Centers for Disease Control, 1600 Clifton Road NE, Mail Stop EO2, Atlanta, GA 30333, USA
137
TABLE I-AVERAGE TIME TO CONCEPTION BY CONSUMPTION OF CAFFEINATED AND RELATED BEVERAGES
Discussion Our analysis suggest that caffeine consumption has little or effect on the reported time to conceive in fertile women who planned their pregnancy. In addition, caffeine consumption was not a risk factor for primary infertility. These findings differ from those reported for 104 women in whom consumption of about one cup of coffee per day was associated with a 50% reduction in conception rates.’ In our study, time to conceive was similar in women with a wide range of caffeine consumption-from less than one cup of coffee per week (501 mg caffeine per month) to more than no
cups per day (7000 mg per month)-with confidence interval at each level of consumption.
two
*p
Are caffeinated
beverages risk factors for delayed conception?
The
association between time to conceive reported by 2817 fertile women who had recently had a liveborn child and consumption of coffee, tea, and "cola" drinks has been investigated. No evidence for an adverse effect of caffeine was found. For levels of consumption ranging from less than one cup of coffee per week (501 mg caffeine per month) to more than two cups of coffee per day (7000 mg per month), the average time to conceive was similar. The fecundability ratio adjusted for known risk factors for time to conceive was 1·03 (95% confidence interval 0·921·16) between those who consumed more than 7000 mg caffeine per month and those who consumed 500 mg or less per month. Furthermore caffeine consumption was not associated with infertility in 1818 infertile women and their primiparous controls.
decaffeinated coffee, and tea, and the weekly consumption of cola drinks. Other sources of caffeinated beverages (ie, caffeinated non-cola drinks) were not included in the questionnaire. Total caffeine consumption per month was calculated as: one cup of coffee contained 100 mg caffeine, tea 50 mg, and cola drinks 40 mg.1 The total caffeine consumption per month was then divided into the same five levels used by Wilcox et al.1 Fertility in relation to caffeine consumption was evaluated in four ways. The first three methods were based on the reported time to conceive the last child in the group of 2817 women: (a) the mean time to conceive was computed for women consuming different amounts of caffeine; (b) a fecundability ratio was computed for conception rates, month by month, and (c) a fecundability ratio (risk ratio) based on a proportional hazards model was computed to examine the independent effects of several factors.6 The fourth method was based on case-control comparisons of caffeine
consumption between women with primary infertility (cases) and primiparous controls.
Results The
Introduction Women who consume more than 3150 mg caffeine per month, the equivalent of one cup of coffee per day, have been reported to have conception rates 50% lower than women who consume less caffeine.1 We have studied the relation between fertility and the consumption of caffeinated and related beverages and other factors among women without a history of infertility and among women with
figure shows the distribution of the reported time to conceive by the 2817 women with a planned pregnancy. The median time was 2-0 months and the mean was 4-5 months; 6% of the women reported that it took longer than 12 months to conceive. .9 -
primary infertility. Patients and methods study groups were 2817 women without a history of infertility who, between April, 1981, and September, 1983, delivered a livebom child as a result of a planned pregnancy at one of seven institutions in the USA and Canada (Brigham and Women’s Hospital, New England Fertility and Gynaecology Associates, the University of Vermont, the University of Colorado, the University of Kentucky, the University de Sherbrooke, and George Washington University), and 1818 infertile women, who between January, 1981, and June, 1983, presented to the same institutions with primary infertility.2 Both groups were interviewed with the same questionnaire, which contained questions on sociodemographic factors, menstrual, reproductive, and general medical history, sexual activity, contraceptive use, cigarette, marijuana, and cocaine use, the consumption of alcohol, coffee, tea, and "cola" soft drinks, and on other habits. Information was retrospectively collected on time to conceive, cigarette smoking, and consumption of alcohol, coffee, tea, and cola drinks. Our main aim had been to investigate the relation between use of intrauterine devices and infertility but data were collected to study other determinants of fertility. The relation between infertility and contraceptive use and cigarette smoking has been reported.2-5 The variables relating to caffeine consumption included in these analyses were: the reported average daily consumption of ordinary coffee, The
Distribution of reported time to conception in 2817 women with a
planned
pregnancy.
For each type of caffeinated beverage except tea the time taken to conceive was unrelated to increasing levels of consumption (table 1). The monthly probability of conception for women consuming more than 3150 mg ADDRESSES: Division of Sexually Transmitted Diseases, Center for Prevention Services, Centers for Disease Control, Public Health Service, US Department of Health and Human Services, Atlanta, Georgia (M R. Joesoef, MD, V. Beral, MRCP, R. T. Rolfs, MD, S. O. Aral, PhD) and Department of Obstetrics and Gynecology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, USA (P. W. Cramer, MD, ScD). Correspondence to Dr M. R Joesoef, Division of Sexually Transmitted Diseases, Center for Prevention Services, Centers for Disease Control, 1600 Clifton Road NE, Mail Stop EO2, Atlanta, GA 30333, USA
137
TABLE I-AVERAGE TIME TO CONCEPTION BY CONSUMPTION OF CAFFEINATED AND RELATED BEVERAGES
Discussion Our analysis suggest that caffeine consumption has little or effect on the reported time to conceive in fertile women who planned their pregnancy. In addition, caffeine consumption was not a risk factor for primary infertility. These findings differ from those reported for 104 women in whom consumption of about one cup of coffee per day was associated with a 50% reduction in conception rates.’ In our study, time to conceive was similar in women with a wide range of caffeine consumption-from less than one cup of coffee per week (501 mg caffeine per month) to more than no
cups per day (7000 mg per month)-with confidence interval at each level of consumption.
two
*p
