Effects of cigarette smoking upon clinical outcomes of assisted reproduction: a meta-analysis

The aim of this meta-analysis was to investigate whether any difference exists in success rate of clinical outcomes of assisted reproductive technologies (ART) between women who actively smoke cigarettes at the time of treatment and those who do not. An intensive computerized search was conducted on published literature from eight databases, using search terms related to smoking, assisted reproduction and outcome measures. Eligible studies compared outcomes of ART between cigarette smoking patients and a control group of non-smoking patients and reported on live birth rate per cycle, clinical pregnancy rate per cycle, ectopic pregnancy rate per pregnancy or spontaneous miscarriage rate per pregnancy, and 21 studies were included in the meta-analyses. Pooled odds ratios (OR) and 95% confidence intervals (CI) were calculated for the data, and statistical heterogeneity was tested for using chi(2) and I-2 values. A systematic review examined the effect of smoking upon fertilization rates across 17 studies. Smoking patients demonstrated significantly lower odds of live birth per cycle (OR 0.54, 95% CI 0.30-0.99), significantly lower odds of clinical pregnancy per cycle (OR 0.56, 95% CI 0.43-0.73), significantly higher odds of spontaneous miscarriage (OR 2.65, 95% CI 1.33-5.30) and significantly higher odds of ectopic pregnancy (OR 15.69, 95% CI 2.87-85.76). A systematic literature review revealed that fertilization rates were not significantly different between smoking and non-smoking groups in most studies. This meta-analysis provides compelling evidence for a significant negative effect of cigarette smoking upon clinical outcomes of ART and should be presented to infertility patients who smoke cigarettes in order to optimize success rates.