partner recently smoked had a significantly lower live
birth rate with IVF or ICSI (7.8% vs 21.1% in nonsmoking
males) [24]. Furthermore, a significant association was identi-
fied between recent female smoking and the decreased ability
to retrieve ova during IVF [24]. A second study examined
221 couples undergoing IVF (aged
20 years) and found that
in couples in which either member had a positive smoking his-
tory, an increased relative risk (2.41) of not achieving a preg-
nancy was present (compared with nonsmoking couples) [25].
This relative risk was even higher (4.27) among couples that
had smoked for
5 years. This trend extended to women who
had smoked at some point in their lives (adjusted risk of
2.71 for not achieving a pregnancy).
Joesbury et al. [26] performed a study on 498 couples
undergoing IVF in which the male partner
s smoking resulted
in a significantly lower chance of achieving a 12-week preg-
nancy. These odds of pregnancy were decreased by 2.4% for
each additional year of male age, suggesting that smoking
and increasing male age acted in concert to affect fertility
potential. A study of 301 German couples demonstrated that
paternal smoking was associated with significantly reduced
success rates for IVF (18% vs 32% in nonsmokers) and ICSI
(22% vs 38% in nonsmokers) [27]. In fact, logistic regression
analyses found that paternal smoking was a significant risk
factor for IVF and ICSI failure, whereas maternal smoking
was a risk factor only for IVF failure. Thus, paternal smoking
may play at least as great a role in the success of assisted
reproduction techniques as maternal smoking.
Prenatal smoking exposure and future fertility
In addition to the effects of cigarette smoking on a man
semen parameters, exposure to cigarettes in utero may have
an impact on a man
s ultimate fertility in the future. Although
the studies in this area are limited, given the long-duration
follow-up that is required, several important pieces of data
are known.
A retrospective study of 1770 male European military
recruits demonstrated that men who had prenatal exposure to
smoking had a 20.1% lower sperm density as adults than
those recruits without such exposure [28]. Men with intrau-
terine smoking exposure also had modest but statistically sig-
nificant reductions in sperm motility and testis size. A more
focused study on 945 Danish men suggested a trend toward
decreasing sperm concentration in adult men with prenatal
exposure to maternal smoking, although the results did not
achieve statistical significance [29]. However, the cohort did
demonstrate a significantly increased risk for oligospermia
among men whose mothers smoked
10 cigarettes per day
during pregnancy. Unfortunately, the degree to which this
oligospermia translates to male fertility potential is not
A further study by Storgaard et al. [30] observed that men
whose mothers were classified as high level smokers
10 cigarettes per day) during pregnancy had a 48%
lower sperm density than men who were not exposed to ciga-
rettes in utero. Of note, this association was not significant in
the subset of men whose mothers were in the lower smoking
category (i.e.
10 cigarettes per day during pregnancy),
suggesting dose dependence in the relationship between in
utero cigarette exposure and subsequent semen abnormalities.
Second-hand smoke and the effects on fertility
Smoking is not a risk factor but can still be considered in iso-
lation. Paternal first-hand smoking often results in maternal
second-hand smoke exposure, which can have further detri-
mental effects on female fertility. One retrospective study of
225 women undergoing IVF/ICSI found that women exposed
to second-hand smoke had implantation rates that were com-
parable to those of women who directly smoked (12.0% vs
12.6%) and were significantly lower than the implantation
rates of unexposed women (25.0%) [31]. Similarly, women
exposed to second-hand smoke experienced a significantly
lower pregnancy rate than women not exposed to cigarette
smoke (20.0% vs 48.3%) [31]. Although data examining the
direct effect of second-hand smoke on females attempting to
conceive naturally is limited, this exposure may decrease the
likelihood of achieving pregnancy by adversely affecting
both male and female factors.
Limitations and future directions
The previously published data on the effects of smoking on
infertility are not without limitations. First, much of the data
presented herein is retrospective in nature and, as such, there
is a dearth of longitudinal prospective literature examining
the relationship between smoking and infertility. Second, the
setting in which patients are selected for the studies are crit-
ical. For example, examination of the effects of smoking on
fertility among men with infertility and those undergoing vas-
ectomy reversal yields different results, as detailed above.
This dichotomy lends itself to diverse and sometimes con-
flicting study results. Nonetheless, evidence supporting an
adverse effect of smoking on several key semen parameters is
strong, irrespective of study design. Future studies should
attempt to further elucidate the possible mechanisms in this
relationship. Third, many of the studies reviewed utilize
semen analysis parameters as primary end points. Future
studies should also prospectively analyze the impact of smok-
ing on fertility while incorporating successful pregnancy rates
as main outcome measures.
Although a large volume of retrospective data exists examin-
ing smoking and the effects on semen analysis parameters
and IVF outcomes, large-scale, population-wide studies on
the effects of smoking on natural pregnancies are lacking.
Nevertheless, the majority of the evidence points to the fact
that men with infertility, or those having difficulty conceiv-
ing, should quit smoking to optimize their chances for suc-
cessful conception.
Declaration of interest
LI Lipshultz is a consultant and member of the speakers
bureaus of Auxilium, Lily, and Endo. JR Kovac is a National
J. R. Kovac et al.
Postgrad Med, 2015; 127(3):338
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