Nikki Woodard 10317048
Smoking and Fertility
Investigative Review
Nikki Woodard
It is common knowledge that cigarette smoking is harmful for the smoker and those around them. There is undisputed evidence that it causes heart disease, vascular disease, lung cancer, throat cancer and can even result in amputation to save the smoker’s life. Smoking and pregnancy is a hot topic because mothers continue to smoke even though they are told it can be detrimental to their baby’s health. Now studies are even suggesting that smoking can decrease a person’s fertility, this hypothesis is not accepted widely. Each year government injects large amounts of money into health campaigns to get smokers to quit. This is the reason some people speculate that sometimes the figures may be exaggerated to make them more effective at scaring people into quitting. The objective of this investigative review was to examine the studies and statistics behind the statement ‘smoking decreases fertility’ to reveal its integrity or exaggeration.
There is no doubt that any medical / human biology / physiology text book in recent history and present adopt a negative view towards smoking and its reproductive effects. However, most (if not all) cannot explain exactly why or how, with many providing broad phrases such as ‘cigarette smoke can reach the foetus and have adverse effects’10. To the educated reader, without any evidence or hypothesised explanation, this comment should mean nothing more than the expression of the writer’s speculation. In other texts it is said that smoking contributes to foetal and infant mortality, ectopic pregnancy, anencephaly, cleft lip and palate and cardiac abnormalities12 or that smoking effects birth weight and is a contraindication for steroidal contraception9. These concepts are never followed by any proof or suggested as hypotheses being studied but are presented as fact. The only explanations offered come from Everitt’s text11. Everitt suggests smoking impairs intercirculatory exchange within the placenta, hence affecting the level of nutrients supplied to and waste removed from the baby therefore hindering development. Although it seems most likely that the toxic chemicals in cigarette smoke that harms children and adults (which is well accepted and supported) will in fact harm an unborn foetus, there has not been any outright proof shown and reports done on any study on this topic or on the topic of its effects on fertility are not readily available to the public for their own analysis, which greatly impeded this investigation. Compared to reports on other topics such as premenstrual tension or any other area in reproduction the reports on the studies done on smoking and fertility have much more restricted access. All the reports found in the process of this investigation required some kind of membership to an association or you had to pay a fee to read them. This in itself adds fuel to the idea that maybe there is some degree of exaggeration in the findings, especially because most other reports on other topics are so easily accessible.
Access, however, to journals reviewing smoking and fertility studies were readily available. One journal review reported nicotine’s detrimental effects on egg maturation, ovulation rates and fertilisation rates in mice. Nicotine was also found to cause chromosome abnormalities in exposed eggs7. This journal also states there was evidence that male smoking decreases success with I.V.F. and that ovarian drilling does not seem to work for women who smoke. No results or statistics were given to support any of these comments which was surprising given the boldness of the last statement. A patient fact sheet from the American Society for Reproductive Medicine3 states “virtually all scientific studies support the conclusion that smoking has an adverse impact on fertility”, it goes on to say the reason being is that the toxins in cigarettes are harmful to the ovaries, the degree of harm dependent upon the amount and period of time a woman smokes. Again no supporting figures and the cited study was inaccessible.
The information surrounding the effect to male infertility seems a bit more extensive with actual numbers given. In the University of Buffalo Reporter7 it was stated that for couples where the male partner smoked it took an average of 3.1 years to conceive compared to 2.6 years for non-smokers, and sexual intercourse for smokers occurs 5.7 times a month and 11.6 a month for non. It is important to question the reliability of comments such as these, if the study’s methods were available factors such as the number of people in the study, length of time they were studied, confounding variables, p-values and other statistical tests could be analysed to examine the integrity of the proclaimed results. In all journals reviewed the same problem was encountered, all statements with some numbers but no firm data.
In the search for studies for this investigation there was one that was accessible a retrospective study of female radiographers entitled ‘The Effect of Reproductive History on Future Pregnancy Outcomes’ that was undertaken in 199810. It involved 3053 female radiographers with 6993 pregnancies; the aim of the study was to see if exposure from anything in their occupational environment caused any reproductive risk. To properly examine that risk other risk factors had to be analysed as well, such as pregnancy/fertility history, maternal age and smoking. The results from this study showed “all data for effect of smoking were insignificant” and “no consistent patterns of risk associated with smoking status”. Of the 3053 women questioned 1050 were current smokers or had been smokers for a significant part of their life. The p-value from the results examining live births from non-smokers compared to live births from smokers was 0.24, which is insignificant suggesting there is no difference between the two groups.
Due to the difficulty in attaining the reports for the studies into the effect of smoking on fertility, the question behind this investigation is still mostly unanswered. The information from various journals strongly support the hypothesis that smoking is detrimental to fertility, but could not go as far as giving some real data to provide evidence, text books take the same stance. An association that would be an authority on the issue, the American Society for Reproductive Medicine, maintains there are studies which support the conclusion that smoking has an adverse impact on smoking. Another authority, The University of Buffalo, states that smokers are less sexually active and take about 6 months longer to get pregnant. To examine the integrity of these opinions and figures more information, which is unavailable, is needed. The only study which was available stated no link between fertility risk and smoking, the results from one study is not enough to draw any conclusions on this topic though. To investigate this issue more thoroughly it would be necessary to acquire access to some organisations’ subscriptions, which is costly. This could suggest someone does not want this information readily available. For now the idea that smoking causes infertility is not widely accepted and probably won’t be until some firm factual evidence is exposed.
References
1. Shiverick KT, Salafia C (1999) Cigarette smoking and pregnancy I: ovarian, uterine and placenta effects Placenta, 20, 265-272
2. Ashley MJ (1987) Smoking, alpha 1-antitrypsin and decreased fertility in womenMedical Hypothesis, 22, 277-285
3. (2003) Patient fact sheet; smoking and fertilityAmerican Society for Reproductive Medicine
4. Oakeshott I (2004) Pregnant smokers risk son’s fertility, Health Correspondent Evening Standard
5. Oakeshott I (2004) Smoking link to infertility, Health Correspondent Evening Standard
6. Orr L (2001) Weak sperm count does not always mean infertility, study says, University of Rochester Medical Centre
7. Baker L. (2003) Nicotine linked to InfertilityUniversity of Buffalo Reporter, 34, n12
8. Zitzmann M, Nordhoff V, Schrader G, Rickert-Fohring M, Gassner P, Rolf C, Greb R, Kiesel L, Nieschlag E (2002) Smokers male partners impair success of ICSI and IVF Andrologia, 34(4), 263-287
9. Hughes EG, Lamont DA, Beecroft ML, Wilson DMC, Brennan BG, RiceSC (1999) Randomised trial of a “stage of change” oriented smoking cessation intervention in infertile and pregnant women, Fertility and Sterility
10. Whitely E, Doyle P, Roman E, De Stavola B (1999) The effect of reproductive history on future pregnancy outcomes, Human Reproduction, 14, 2863-2867
11. Johnson M, Everitt B (2000) Essential Reproductive 5th Edition Blackwell Science, Australia.
12. Saladin K (2001) Anatomy and Physiology; the unity of form and function 2nd editionMcGraw Hill, New York.
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