Cigarette smoking and infertility.

 Cigarette smoking and infertility.

Incidence

About 30% of reproductive-age women and 35% of reproductive-age men in the US smoke cigarettes. In addition, many adolescents and teenage girls, despite costly and long-standing campaigns to limit their use. Several studies have shown a causal association between cigarette smoking and infertility. Therefore, in this article, we discuss the consequences of cigarette smoking on infertility.

Infertility Statistics:

In the UK, infertility affects about 1 in every 6-7 couples. Infertility is a global factor health issue; causes include male factors, female factors, combined factors, and idiopathic (unknown) aetiologies. It is a multidimensional problem with socio-economic, cultural, and spiritual implications. In addition, it is a cause of marital disharmony and distress to couples. Childbearing and raising children are significant events amongst couples. Especially those of African descent, strongly associated with the ultimate goals of fulfillment, happiness, and family completeness.

According to WHO, approximately 34 million women, predominantly from developing countries, have infertility problems that result from maternal sepsis and unsafe abortion (long-term maternal morbidity resulting in a disability). Infertility in women has ranked the 5th highest global severe impairment (among populations under the age of 60).

Although infertility is a global menace, variations in incidence are associated with geographical differences. For instance, the incidence rate may be as high as 50% in some West African communities. Compared to about 12% in some Western countries. Country variations still exist even within the same geographical region.  Such as Europe, with higher incidence rates recorded in less developed countries than the developed ones. The most frequent cause observed, especially in Western countries, is an advanced maternal age. Whereas compared to sexually transmitted diseases (STDs) in sub-Saharan Africa.

Definition of Infertility:

Infertility is the inability of a couple to achieve spontaneous conception after trying for at least six months.  In addition, one year for women over 35.  Without using any contraception despite adequate (at least 2 to 3 times on alternate days) sexual (peni-vaginal) intercourse. Aside from advanced maternal age, STDs, and congenital/genetic causes. Moreover, endocrine causes, chemotherapy, exposure to radiation, and other known causes of infertility. In addition, lifestyle patterns and environmental pollutants such as cigarette smoking play a crucial role in infertility. According to the CDC, smoking causes about 500,000 deaths yearly in the US, about 1 in 5.

Smoking effects:

A study published by the US Centre for Disease Control and Prevention (CDC) showed that while smoking rates among women worldwide have fallen recently, smoking remains a significant cause of newborn deaths, preterm births, and babies with LBW. A systematic review of the scientific literature on the impact of cigarette smoking and smoke constituents revealed that all stages of reproductive functions are targets of cigarette smoke toxicants.

Hence, it is critical to note the consequences of cigarette smoking on infertility. In the UK alone, smoking during pregnancy is responsible for about 5,000 miscarriages, 3,000 perinatal deaths, and approximately 2,000 premature births yearly. According to WHO, smoking causes more deaths in one year than all: deaths due to HIV, illegal drug use, alcohol use, motor vehicle injuries, and fire-related incidents. Smoking causes about 80% of deaths from COPD and 10% of all lung cancers in males and females. More people die from lung cancer each year than from breast cancer.

Smoking and Infertility:

Several studies have established a causal relationship between the consequences of cigarette smoking and infertility. They confirm that women who smoke take longer to conceive than those who do not. Some studies found that tobacco use affects the receptivity of the uterus, particularly among heavy smokers. There’s also a higher incidence of ectopic pregnancies among smokers. Comparatively, low-level smoking, ‘sidestream,’ and passive smoking can harm fertility. There is recent evidence which suggests that smoking affects the success rate of fertility treatment. Research has depicted that women undergoing assisted reproductive treatment have a significant negative outcome compared to non-smokers. A study even showed a 50% decline in implantation rate in smokers. 

Worse IVF parameters express the impact of tobacco compounds in ovarian follicle maturation in cycles performed on women with smoking habits; this, as well as uterine receptiveness and tubal function, are significantly altered by the smoking habit.

Furthermore, smoking causes a reduction in the number of germ cells (sperm and egg-forming cells) and somatic cells (cells that form the body parts) in utero. It can also affect protamine, a protein essential for sperm production. Males born to women who smoked during pregnancy are at risk of having small testes, low sperm counts, and low sperm concentration. These men also have a high number of malformed sperm. Traces of Nicotine – by-products are in the semen of such men. They reduce sperm motility and their fertilization potential. 

Smoking and Alcohol:

Several studies confirm the effects of smoking and alcohol consumption on our lifestyle and social behavior have, over the years, harmed fertility and in early pregnancy losses, preterm births, and low birth weight babies. Alcohol consumption affects male and female fertility, but the level associated with risk is unclear. Studies are limited and rely mainly on recall of time and quantity of alcohol consumed. 

Mechanisms by which alcohol impairs fertility are unclear, but in men, it can cause impotence, reduced libido, and affect sperm quality. In men, the effects of smoking manifest in a reduction in sperm production, an increase in oxidative stress, and DNA damage. ‘Sperms from smokers have to decrease fertilizing capacity,’ and embryos have reduced implantation capabilities, hence a decrease in implantation rates. 

Smoking and Oxidative Stress:

High maternal alcohol consumption is known to be dangerous to the unborn child, and it decreases the chance of live birth and increases the risk of miscarriage. Smoking and excessive alcohol consumption can achieve their adverse effects singly or in synergy. Women who smoke reach menopause earlier (1 – 4 years more) than non-smokers, shortening their reproductive lifespan. Basal FSH (Follicle-stimulating hormone) levels are 60% – 70% higher in active smokers than in non-smokers. Parallel to this quantitative effect on follicles, reports indicate a qualitative impact on steroidogenesis, follicular growth, oocyte maturation, fertilization, and embryo development.

Recent data have suggested that oxidative stress plays a crucial role in the pathophysiological process involved in fertility reduction related to the quality of both gametes. Evidence showed that polycyclic aromatic hydrocarbon in tobacco could trigger premature cell death that causes early menopause. Insofar as no research demonstrates that ‘safe’ levels of smoking correlated with preserved fertility. It implies that even light smoking is associated with reduced fecundity. 

How does smoking affect infertility in the female?

Many of the effects of tobacco on infertility may ultimately be related to the oxidative impacts. We know reactive oxygen species (ROS) can damage every molecule inside the cell: carbohydrates, proteins, lipids, and DNA. Tobacco exposure also alters the meiotic spindle of oocytes in women, leading to ‘dysjunctional’ errors. Studies by Zenzes et al. showed that cotinine is detectable in follicular fluids. Cotinine (an alkaloid) is a metabolite of nicotine, a tobacco end product “that results in oxidative stress to the gametes.” Its presence in the blood is proportionate to the amount of exposure to tobacco smoke in both active and passive smokers. 

In females, smoking affects the ovaries adversely. The degree of damage is dependent upon the quantity and length of time a woman smokes. Nicotine and other hazardous substances in cigarettes interfere with the body’s ability to create estrogen, which regulates follicular growth and ovulation. Smoking interferes with folliculogenesis, embryo transplant, endometrial receptivity, endometrial angiogenesis, uterine blood flow, and the uterine endometrium. Smokers are 60% more likely to be infertile than non-smokers. Smoking decreases the chances of IVF producing a live birth by 34% and increases the risk of an IVF pregnancy miscarrying by 30%. Some damage is irreversible, but stopping smoking can prevent further damage.

How does smoking affect infertility in the male?

In males, oxidative stress occurs in the seminal fluid of smokers. Increased concentrations of cadmium, lead, and ROS are significantly higher. At the same time, levels of ascorbic acid and the activity of other components of the antioxidant defense reduced considerably. Ascorbic acid is the major extracellular water-soluble antioxidant. Therefore, the scavenging capacity of the antioxidant defense system is severely impaired.

The incidence of impotence is approximately 85% higher in male smokers than non-smokers and is a significant cause of erectile dysfunction (ED). Smoking causes infertility by encouraging arterial narrowing.

Fathers who smoke heavily (greater than 20 sticks per day) at conception increase the child’s risk of childhood Leukaemia.  And shorten the reproductive lifespan of their daughters. Evidence has also suggested damage to female infertility in utero if the woman’s mother was exposed to secondhand smoke while pregnant. Also, women exposed to cigarette smoke while undergoing IVF or other assisted reproduction technologies treatment can have adverse pregnancy outcomes. More epidemiological research is needed to bolster these suggestions.

Dangers of secondhand smoking:

Secondhand tobacco smoke is a known reproductive toxin comprising a mixture of at least 4,000 chemical compounds. Non-smokers exposed to secondhand smoke are at risk of difficulty becoming pregnant, having a spontaneous abortion, having babies with congenital malformations, or having stillbirths. Chemicals in tobacco smoke alter endocrine functions, affecting the release of pituitary hormones. This endocrine disruption contributes to adverse outcomes, including early menopause.     

Smoking can also reduce the chances of a woman becoming pregnant. And affect her baby’s health before (in utero) and after (postpartum). In addition, it alters man’s sperm, reducing fertility and increasing the risks of congenital disabilities and miscarriages. It does this by damaging sperm DNA.

Smoking as a leading cause of infertility:

Smoking is one of the leading causes of infertility. Many men and women of reproductive age continue to smoke. And only a tiny proportion of them consider quitting. Pregnant women attempt to stop when they are pregnant, unlike at any other time. Support should come from the baby’s father. And family members, friends, and the health care system. In addition to pregnancy, the smoking helpline, smoking cessation groups, etc.

A Cochrane review in 2009 found that interventions from health professionals reduced the proportion of people smoking in late pregnancy by 6% overall. The most effective response, particularly among low-income people, was providing incentives that helped about 25% of women quit smoking during pregnancy. Couples of reproductive age should quit smoking. However, the causal effect of smoking and the decline in fecundity has not been as unanimous as expected. Despite this, given the available literature and studies, critics believe that the strength of the association is varied. And a larger sample size is required. However, this does not mean that the association is not clinically relevant. 

Research outcome:

Studies on sperm production, for instance, make this particularly relevant. Biological plausibility for the association between smoking and impaired fecundity is abundant. Studies done on ovarian tissues show that chemicals in cigarette smoke appear to deplete follicles (fluid-like sacs containing the egg) acceleratedly. Furthermore, authorities can give appropriate guidelines to stop smoking in primary, secondary, and tertiary centers. And must be implemented. Healthcare practitioners should work in unison to reduce smoking during pregnancy and postpartum (after delivery).

Prevention:

The government should enact legislation against public smoking and smoking at workplaces to reduce the effects of passive smoking. We strictly discourage indoor smoking and smoking in vehicles. In addition, it is creating designated smoking areas, especially in public places. The government should also mandate tobacco companies to inform the citizens of the harmful effects of smoking on fertility. 

Conclusion:

Conclusively, cigarette smoking reduces female fertility natural cycles and assisted reproductive cycles. Embryos generated from the sperms of smokers have reduced implantation potentials. The lack of consensus among studies reflects the aforementioned methodological difficulties, but clinical evidence supports nicotine’s harmful effects on conception.