The effects of maternal cigarette smoking on pregnancy outcomes using assisted reproduction technologies: An updated meta-analysis

Smoking and recurrent pregnancy loss: A cohort study of 2829 women

Smoking during pregnancy is associated with negative reproductive outcome. Less is known about the impact of smoking or previous smoking in women with recurrent pregnancy loss (RPL) which this study aimed to investigate. We included all women <42 years (n=2829) referred to a RPL unit at Copenhagen University Hospital between January 2000 and December 2021 in the cohort with follow-up until June 2022. Patients were categorized as 'smokers at time of referral', 'never-smokers' or 'former smokers'. The main outcomes were pregnancy history prior to referral, prospective pregnancy rate, live birth rate, rates of ectopic pregnancy, and stillbirth. At referral, smokers (n=373) were on average 2.0 years younger (P<0.001) and had experienced significantly more pregnancy losses (P<0.001), and stillbirths (P=0.01) compared to never-smokers (n=2100). Former smokers had a higher risk of stillbirth prior to referral compared to never-smokers but no differences in pregnancy rate or other outcomes. Prospective pregnancy rates were lower for smokers compared with never-smokers (71.8% vs. 77.5%, P=0.02). Live birth rate was 58.0% for the 243 women who smoked at referral compared to 61.4% for the 1488 never-smokers (P=0.32). Stillbirth and ectopic pregnancies were significantly more common for smokers (2.8% vs. 0.4%, P=0.01; 6.0% vs. 2.0%, P<0.008). Women with RPL who smoked at referral were referred younger with a higher number of previous pregnancy losses and stillbirths compared with never-smokers. Fewer smokers achieved a pregnancy after referral but those who did had a similar live birth rate compared to never-smokers, although stillbirths and ectopic pregnancies were more common.

Tobacco or marijuana use and infertility: a committee opinion

In the United States, approximately 21% of adults report some form of tobacco use, although 18% report marijuana use. Although the negative impact of tobacco use in pregnancy is well documented, the impact of tobacco and marijuana on fertility and reproduction is less clear. This committee opinion reviews the potential deleterious effects of tobacco, nicotine, and marijuana use on conception, ovarian follicular dynamics, sperm parameters, gamete mutations, early pregnancy, and assisted reproductive technology outcomes. It also reviews the current status of tobacco smoking cessation strategies. This document replaces the 2018 American Society for Reproductive Medicine Practice Committee document entitled Smoking and Infertility: a committee opinion (Fertil Steril 2018).

Effect of Male Cigarette Smoking on In Vitro Fertilization (IVF) Outcomes and Embryo Morphokinetic Parameters

This retrospective cohort study examines the association between male smoking status and embryo development in vitro. The study included non-smoking women aged under 40 years who underwent in vitro fertilization (IVF) at Yanaihara Women's Clinic from May 2019 to May 2022, and they were divided into two groups according to the husband's smoking status. The effect of male smoking status on IVF outcomes was compared retrospectively based on embryonic development using a time-lapse incubator. A total of 184 patients were included; 272 oocytes of 45 female non-smokers were cultured with the sperm of male smokers, and 816 oocytes of 139 female non-smokers were cultured with the sperm of male non-smokers. No significant differences were observed between male smokers and non-smokers groups with regard to fertilization and the top-quality embryo on day 3 and day 5 (p > 0.05). The male smoker group's embryos reached the early cleavage-stage parameters (time of pronuclei appearance to the five-cell stage) significantly earlier than the male non-smoker group's embryos (p < 0.05). However, no significant differences were observed between the two groups in other parameters of top-quality blastocysts (p > 0.05). It was concluded that male smoking has some differences on the timing of early embryonic events on time-lapse examination.

[Male infertility, environment and lifestyle]

BACKGROUND

Since the 1970s, there has been a quantitative and qualitative decline in sperm parameters. The main hypothesis to explain such a rapid evolution is the involvement of environmental and behavioral phenomena.

METHODS

A bibliographic search limited to English and French literature in men published before 7/2023 was carried out on the links between fertility and pollution, xenobiotics, tobacco, narcotics, cannabis, alcohol, weight, sport, sedentary lifestyle, sleep and anabolics.

RESULTS

Profound changes in lifestyle have occurred over the past 50 years: reduced sleep time, sedentary lifestyle, dietary changes, tobacco consumption, use of narcotics and anabolics. These changes have a proven impact on spermogram parameters, and should be corrected in an effort to optimize reproductive health. Other environmental parameters: pollution, exposure to heavy metals, exposure to xenobiotics, phthalates and pesticides… will be more difficult to exclude from patients' daily lives, but deserve to be taken more into account.

CONCLUSION

This review should help the urologist to assess and counsel patients in order to improve their reproductive health. These factors should be routinely investigated in infertile men.

[Electronic cigarettes and fertility: True or false friends?]

While electronic cigarettes have been on the rise in France for the past ten years, data on their prevalence, use patterns and safety have remained fragmented and controversial. Electronic cigarettes seem to not be a harmless product to use, because although they contain fewer harmful substances than traditional cigarettes, they still contain toxic products such as endocrine disruptors, which appear to have a negative impact on hormonal homeostasis, morphology and functioning of the animal reproductive system. Mostly presented as a harmless alternative to traditional cigarettes by industry lobbies, electronic cigarettes are often offered as an aid to smoking cessation in the same way as nicotinic substitutes. This strategy is especially proposed without knowledge of its effects on human reproductive health. Indeed, there are currently very few scientific publications, which study the impact of the use of electronic cigarettes, nicotine and the vapours it delivers on fertility and the functioning of the human female and male reproductive systems. Thus, the great majority of the data we have to date come from studies carried out in animal populations and show that electronic cigarettes exposure affect fertility. There is, to our knowledge, no scientific publication on the results in Assisted Reproductive Technology in case of use of electronic cigarettes, motivating the realization of the study IVF-VAP currently underway in the department of Medicine and Biology of Reproduction of the Amiens Picardie University Hospital.

Mechanism of Human Tubal Ectopic Pregnancy Caused by Cigarette Smoking

In the past few decades, the smoking rate of women of childbearing age has increased. Epidemiological data has repeatedly shown that smoking women have an increased risk of various reproductive diseases, including ectopic pregnancy (EP), decreased fertility, adverse pregnancy outcomes, and failure of assisted reproduction. The oviduct was the target of cigarette smoke in many in vivo and in vitro studies. The fallopian tube is a well-designed organ. Its function is to collect and transport the ova to the fertilized site and provide a suitable environment for fertilization and early embryonic development. Lastly, the fallopian tube transports the pre-implantation embryo to the uterus. Various biological processes can be studied in the fallopian tubes, making it an excellent model for toxicology. This paper reviews the roles of the fallopian tube in gametes and embryo transportation, and the possible mechanism tobacco smoke contributes to tubal EP. A possible signal pathway might be a model to develop intervention of EP for pregnant women exposed to smoking.

Airway pollution and smoking in reproductive health

Environmental exposure refers to contact with chemical, biological, or physical substances found in air, water, food, or soil that may have a harmful effect on a person's health. Almost all of the global population (99%) breathe air that contains high levels of pollutants. Smoking is one of the most common forms of recreational drug use and is the leading preventable cause of morbidity and mortality worldwide. The small particles from either ambient (outdoor) pollution or cigarette smoke are inhaled to the lungs and quickly absorbed into the bloodstream. These substances can affect virtually every organ in our body and have been associated with various respiratory, cardiovascular, endocrine, and also reproductive morbidities, including decreased fertility, adverse pregnancy outcomes, and offspring long-term morbidity. This review summarizes the latest literature reporting the reproductive consequences of women exposed to ambient (outdoor) air pollution and cigarette smoking.

Cigarette smoke is associated with up-regulation of inducible NOS and COX-2 protein expression and activity in granulosa cells of women undergoing in vitro fertilization

Cigarette smoke exposure represents a well-established ovotoxic exogenous stress, but the molecular mechanisms underlying of this effect are still unclear. Cigarette smoke upregulates inflammatory genes in the female reproductive organs, therefore an abnormal inflammation response may contribute to the impairment of female fertility. In this study we investigated for the first time the effect of cigarette smoke exposure on NOS and COX expression and activity and on their transcription factors (CREB and NF-kB) in human GCs and on the release of NO and PGE₂ in the FF in smoking and non-smoking patients undergoing IVF treatment. In addition, correlation analysis between AMH serum levels, an index of ovarian reserve, and smoking exposure or iNOS and COX-2 protein expression levels were performed using a Pearson correlation method. Cigarette smoke exposure resulted in a significant increase of iNOS and COX-2 protein expression together with an increase of iNOS activity and PGE₂ levels. pNF-kB and pCREB protein expression were upregulated in the GCs of smokers compared to non-smokers. The habit of smoking was negatively correlated with serum AMH levels, and positively correlated with iNOS and COX-2 protein expression levels. The data presented in the current study revealed a novel molecular mechanism underlying the toxic effects of cigarette smoke on fertility. Additional pathways mediating the effects of cigarette smoke exposure in human GCs cannot be excluded and should be investigated in future studies.

Impact of Tobacco and Marijuana on Infertility and Early Reproductive Wastage

Reducing exposure to tobacco and marijuana during preconception and early pregnancy is a critical area of intervention for obstetricians, gynecologists, and other reproductive health care professionals. Beyond the deleterious personal health effects, both substances have been extensively associated with short-term and long-term detrimental effects to gametogenesis, fecundity, as well as tissue level effects in the reproductive tracts. When tobacco and marijuana do not impair the ability to achieve pregnancy, an increasing body of literature suggests either may be associated with increased risk of early pregnancy loss and reproductive wastage. In this review, we will discuss what is known about how tobacco and marijuana affect the male and female reproductive systems and highlight how these consequences may impair attempts at successful conception and pregnancy continuation beyond the first trimester.

Pre-pregnancy lifestyle characteristics and risk of miscarriage: the Australian Longitudinal Study on Women's Health

Background

Previous studies of lifestyle characteristics and risk of miscarriage have mostly been retrospective and failed to account for induced abortions. We examine whether pre-pregnancy body-mass index, alcohol intake and smoking influence the risk of miscarriage after accounting for induced abortions.

Methods

We conducted a prospective cohort study of 9213 women with 26,594 pregnancies participating in the Australian Longitudinal Study on Women’s Health. We examined whether body-mass index, smoking and alcohol intake prior to pregnancy was associated with miscarriage. We estimated adjusted relative risks (RR) using generalized estimating equations with an exchangeable correlation matrix. We explored the impact of accounting for induced abortion by first excluding all induced abortions, and secondly including 50% of induced abortions in the comparison group.

Results

Of the 26,592 pregnancies which occurred during the follow-up period, 19% ended in a miscarriage. We observed an increased risk of miscarriage according to pre-pregnancy obesity compared to normal weight (adjusted RR 1.13; 95% CI 1.05, 1.21), smoking between 10 and 19 cigarettes per day compared to not smoking (adjusted RR 1.13; 95% CI 1.02, 1.25), but not smoking 20 or more cigarettes per day (adjusted RR 1.07; 95% CI 0.94, 1.21) and risky drinking (≥2 units per day; adjusted RR 1.15; 95% CI 1.03, 1.28) compared to low risk drinking (< 2 units per day). The results for smoking (adjusted RR 1.09 for 10–19 cigarettes per day; 95% CI 0.98, 1.21) was attenuated after including 50% of induced abortions in the comparison group.

Conclusions

We observed a modest increased risk of miscarriage according to obesity and risky alcohol intake prior to pregnancy. There was no evidence of a dose-response relationship with smoking, and the association between smoking and risk of miscarriage was attenuated after accounting for induced abortions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04482-9.

Female cigarette smoking and successful fertility treatment: A Danish cohort study

INTRODUCTION

Despite smoking being a well-established risk factor for adverse pregnancy and neonatal outcomes, a substantial proportion of women of reproductive age smoke. Previously, meta-analyses have indicated a significantly negative impact of female smoking on outcomes of assisted reproduction, yet most of the included studies have several, essential methodological limitations. We aimed to investigate whether female cigarette smoking may affect the chance of achieving a clinical pregnancy and live birth among women and couples receiving medically assisted reproduction treatment.

MATERIAL AND METHODS

A cohort study with longitudinally and repeatedly collected exposure information from 1 January 2010 to 31 August 2015, including data on 1708 women and potential partners initiating either intrauterine insemination, in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) or frozen embryo transfer treatment cycles at the public Fertility Clinic, Aarhus University Hospital, Denmark. Smoking was assessed from self-reported questionnaires completed before treatment. Outcomes were a clinical pregnancy and a live birth. Information on these was obtained from the Danish national health registries, allowing complete follow-up. To evaluate associations between female occasional/daily cigarette smoking and successful medically assisted reproduction treatments, a modified Poisson regression with robust standard errors was used.

RESULTS

Female occasional/daily cigarette smoking was not associated with the chance of achieving a clinical pregnancy or a live birth in all intrauterine insemination or IVF/ICSI treatment cycles. When compared with nonsmokers, the adjusted relative risk for obtaining a live birth for those reporting smoking was 1.22 (0.70-2.12) among women initiating 1456 intrauterine insemination treatment cycles. Among women initiating 2788 IVF/ICSI treatment cycles, those reporting occasional/daily smoking had a relative risk for obtaining a live birth of 1.15 (0.82-1.60) when compared with nonsmokers.

CONCLUSIONS

Occasionally/daily cigarette smoking women had similar chance of achieving a clinical pregnancy or a live birth as the nonsmokers when receiving medically assisted reproduction treatments. However, tobacco use before and during pregnancy remains a major cause of reduced fertility as well as maternal, fetal, and infant morbidity and mortality, and should strongly be discouraged.