We investigated whether cigarette smoking, measured by follicular fluid concentrations of @entity4874 (a major metabolite of @entity1239 ), affects the maturity of oocytes from @entity1 undergoing @entity52 ( @entity52 ) and embryo transfer. In 234 @entity1 , follicular fluid samples were assessed for @entity4874 and their 2020 oocytes were assessed for maturity stage. Data on individual proportions of oocytes which were mature (OM) and were fertilized (OF) were analysed by regression in relation to age and follicular fluid @entity4874 . OF gave an independent assessment of oocyte maturity. Both age and follicular fluid @entity4874 entered the OM and OF regressions and were significant. The age-adjusted regression coefficients for log @entity4874 were positive; greater @entity4874 concentrations usually accompanied greater OM and OF. The @entity4874 effect on OM was positive in younger @entity1 , but it became negative (decreased OM with increasing @entity4874 concentrations) in older @entity1 (> or = 40 years). We further found in older @entity1 an average reduction of approximately 50% in the number of mature oocytes; this reduced number was lower than the number of embryos usually transferred. Smoking can reduce the number of mature oocytes even further, therefore risking a negative @entity52 -embryo transfer outcome. This may be the reason why the negative effects of smoking become clinically detectable in older @entity1 .

Effects of cigarette smoking and age on the maturation of XXXX oocytes.

@entity1 :: ('9606', 'Species') :: ['women'] @entity1239 :: ('MESH:D009538', 'Chemical') :: ['nicotine'] @entity52 :: ('MESH:C566179', 'Disease') :: ['in-vitro fertilization', 'IVF'] @entity4874 :: ('MESH:D003367', 'Chemical') :: ['cotinine']
@entity1 :: (9606,Species) :: ['human']
