The effect of smoking on oocyte quality and hormonal parameters of patients undergoing in vitro fertilization-embryo transfer

Purpose: The aim of the present study was to investigate the influence of s moking on different parameters such as oocyte count, embryo score, and basa l hormone values within the scope of in vitro fertilization-embryo transfer (IVF-ET). Methods: Eight hundred thirty-four women undergoing IVF ET treatment were c lassified as smokers or nonsmokers on the basis of questionnaires Additiona lly, we divided them into three groups according to their stimulation proto cal-"combined stimulation" [I; clomiphene citrate plus human menopausal gon adotropin (hMG)], "ultrashort" [II; gonadotropin releasing hormone agonist (GnRHa) plus hMG or follicle-stimulating hormone (FSH)] and "long downregul ation protocol" (III)-and further classified again as smokers or nonsmokers within the groups. Results: In general, smoking patients were significantly (P = 0.0195) young er than nonsmokers and showed a significantly (P = 0.0379) lower embryo sco re and a tendency (P = 0.0931) to produce fewer oocytes. There was no signi ficant difference concerning the number of normally or pathologically ferti lized and transfered oocytes and embryos suitable for cryopreservation. Wom en who smoked had significantly (P = 0.0112) higher basal 17-beta-estradiol (E-2), luteinizing hormone (LH) (P = 0.0001), and dehydroepian-drosterones ulfate (DHEAS) (P = 0.0039) levels, bur their basal human prolactin (HPRL) levels were significantly (P = 0.0033) lower than those of nonsmokers. Acco rding to the stimulation protocol used, we found the following results. Smo king patients in group I showed a significantly (P = 0.023) lower embryo sc ore and produced fewer oocytes (P = 0.0113), with fewer of them being ferti lized (P = 0.0072) and transferred (P = 0.0067). Women who smoked had signi ficantly (P = 0.0002) higher basal LH levels, but their HPRL levels were si gnificantly (P = 0.031) lower than those of nonsmokers. Furthermore, they h ad a thinner endometrium on the day of embryo transfer (P = 0.0366). In gro up II we measured significantly elevated basal E-2 levels (P = 0.0089) and higher LH values (P = 0.0092) in smokers. Group III showed a trend (P = 0.0 565) toward lower HPRL values in smokers. Conclusions: Although the fertilization rate of oocytes and the pregnancy r ate were not significantly different between smokers and nonsmokers, we fou nd significantly alterated hormonal parameters and negatively influenced oo cyte parameters, particularly after clomiphene stimulation. So we might con sider using only GnRHa protocols for smoking patients. Additionally. we adv ise our patients to stop smoking before an IVF-ET treatment because of the complex effects of smoking on the reproductive and hormonal system.