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Deleterious Effects Described in Obese Women Undergoing IVF

Impact of Bodyweight and Lifestyle on IVF Outcome: Caffeine



A total of 80% of pregnant women consume caffeinated beverages.[174] Some clinical and epidemiological studies have suggested delayed conception and increased infertility and miscarriage rates in women that consume caffeinated beverages. These effects are dose-dependent, with relative risk of infertility being as high as 4.7 among heavy users.[13,175,176] The threshold at which caffeine affects fertility is not known. Different studies have proposed levels between over 150 mg (1.5 cups of brewed coffee)[177] and over 500 mg (five cups of brewed coffee)[178] per day.

Similar to the case of alcohol intake, there is only one study that has assessed the effects of female and male caffeine consumption on outcome of IVF and GIFT.[176] In total, 221 couples were interviewed about their caffeine consumption (i.e., coffee, soda, tea and chocolate) during different periods of time prior to initiation of the ART procedure. In women, the relative risk of not achieving a live birth was 3.1 (95% CI: 1.1-9.7) and 3.9 (95% CI: 1.3-11.6) for regular intake of over 2-50 and 50 mg/day, respectively. The relative risk also increased when caffeine was consumed during the week of the initial visit, even if in low quantities. The decrease in live births was explained mainly by the significant increase in the miscarriage rate of 19.8 (95% CI:1.3-300.9) and 10.5 (95% CI: 0.9-125.3) in women who usually consumed over 2-50 and 50 mg of caffeine per day (during their lifetime). However, the wide CI resulting from the small sample size of this study makes the association between caffeine and miscarriage somewhat unreliable. In this study, there was also a trend towards lower infant gestational age among women who consumed over 50 mg/day of caffeine usually or during the week of the initial visit. In men who increased their usual intake by an extra 100 mg/day or consumed that quantity of caffeine during the week of the initial visit, the odds of having a multiple gestation increased by 2.2 (95% CI: 1.1-4.4) and 3.0 (95% CI: 1.2-7.4), respectively. Similar results had been previously published with respect to multiple pregnancy and female caffeine consumption, especially over three cups/day.[179] Sperm parameters were not found to be affected, which contradicted previous studies that had shown a relationship with impaired semen quality and increased motility.[180,181] Caffeine intake was not significantly associated with other outcomes.

The main handicap of this study was the inexact knowledge of caffeine consumption, which was only an estimation obtained from patient questionnaires in which data regarding mix of the brew, size of the cup, way of preparation of the beverage and intake of other sources of caffeine, for example dietary supplements, were not correctly recorded. On the other hand, the subjects reported far lower caffeine consumption than that of previous populationbased studies on subfecundity, and these low levels of intake may explain the lack of effect on oocyte retrieval, fertilization, embryo transfer and pregnancy. Moreover, the sample size was insufficient for evaluating some of the outcomes under scrutiny.

Available evidence of the deleterious effect of caffeine on IVF is scant, but based on the study by Klonoff-Cohen et al.,[176] and a reported increased probability of spontaneous abortion or impaired fetal growth during pregnancy,[182,183] the best policy would be to minimize caffeine consumption prior to and while undergoing ART, as well as during pregnancy.

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