Data from the National Cancer Institute (INCA) show that around 10 thousand people die each day in Brazil from problems related to smoking. Among the known harms are cardiovascular problems (heart attack, angina), cancer and chronic obstructive respiratory diseases (emphysema and bronchitis). However, smoking can also affect fertility in both men and women.
“The chemical contained in cigarette smoke seems to accelerate the destruction of eggs”, explains the gynecologist Maria Cecilia Erthal, medical director of the Vida Fertility Center, specialist in human reproduction. According to her, women who smoke up to 20 cigarettes a day are 25% less likely to get pregnant. “In those who smoke more than 20 cigarettes a day this chance is reduced by 43%”, he says. There is also, for them, a greater risk of pregnancy in the tubes.
Toxic substances contained in cigarette smoke, such as nicotine and carbon monoxide, affect reproductive function at various levels, such as sperm production, tubal motility (important for capturing the egg that leaves the ovary at the time of ovulation), the division of the embryo’s cells, formation of the blastocyst (embryo with more than 64 cells) and implantation. Women who smoke may also have a higher incidence of menstrual irregularities and amenorrhea (lack of menstruation). In addition, menopause occurs one to four years earlier in smokers compared to non-smokers. “The chemical contained in cigarette smoke appears to accelerate the destruction of eggs and consequent loss of reproductive function”
During pregnancy, smoking is also harmful and can damage the DNA, thus causing pre-mutation lesions that, by themselves, have many consequences, he explains. “DNA damage increases the incidence of miscarriages, physical defects and some authors even suggest an increase in cases of trisomy 21 [síndrome de Down]”, says the expert.
On this National Anti-Smoking Day, the specialist clarifies some doubts about smoking and fertility. See below.
MARIE CLAIRE Can cigarettes be considered an enemy of those who want to have children? Why?
MARIA CECÍLIA ERTHAL Cigarettes are considered an enemy, yes, for couples looking to have children – this is not only because it reduces natural fertility, but also reduces the chances of pregnancy in assisted reproduction treatments. This is all because the toxic metabolites, the substances that are released by nicotine, are deposited in the ovaries and compromise the ovarian function, damaging the ovarian reserve of follicles, of eggs. Thus, in women who smoke up to 20 cigarettes a day, there is a 25% chance of pregnancy occurring. In those who smoke more than 20 cigarettes a day, this chance is reduced by 43%. And it does not only decrease because it affects the ovarian reserve of eggs, but also the receptivity of the uterus to implantation of embryos, and also in this way increases the risk of miscarriages.
MC What is tubal mobility and why is it important for fertilization?
ME Tubal motility is extremely important for pregnancy to happen. The fertilization, which is the meeting between the egg and the sperm, takes place in the tube itself, in the most distal part. The moment this egg is fertilized, it starts its cell multiplication process to become an embryo, during this multiplication process it will be transported by the tube – it “pushes” – so this mobility of the tube is important, because it pushes this fertilized egg towards the uterus, so that implantation takes place and from there, pregnancy takes place.
MC How does smoking affect menstrual regularity?
ME A woman’s menstrual cycles are totally dependent on ovulatory cycles, on the occurrence of ovulation. Ovulation depends on the presence of follicles, which is the germ tissue that is inside the ovary. Nicotine destroys this germ tissue, destroys this population of follicles, decreases the woman’s egg supply. So the ovulatory cycles decrease and this directly interferes with menstrual cycles. The fewer ovulatory cycles, the more irregular this woman’s menstruation becomes, the cycles become shorter and over time they become sporadic, decreasing in frequency.
MC How can cigarette smoking harm the development of the embryo?
ME There is already evidence that smoking hinders the implantation of the embryo in the uterus, this way, this embryonic development is harmed, because receiving nutrients, receiving blood from the placenta depends on a good embryo implantation. So, if the cigarette interferes with this implantation process, it will therefore hinder the development of the embryo. Remembering that both the vascularization and the blood supply of the placenta are totally impaired in patients exposed to nicotine, this in addition to hindering the process of embryo development, increasing the chances of miscarriage, but those embryos, that pregnancy that manages to move forward often gives origin of babies with underweight at birth and often with premature birth due to the interference that nicotine brings in this placental vascularization and the placenta being the organ responsible for the baby’s nutrition, these babies end up being malnourished, with low weight and a tendency to born prematurely.
MC How can I help a person who is trying to quit smoking but is unable to? What tips for a smoking couple planning to have children?
ME The main step for the person who wants to quit smoking is to really want to, is to have this desire, to have this desire. And seek professional help, there are already doctors specialized in combating nicotine addiction, including the use of medication. So if the couple has this intention, so that the pregnancy occurs more smoothly, avoiding all the harmful effects that cigarettes bring to pregnancy (increased abortions, increased risk of low birth weight, premature births), then what is advised is that they really seek specialized help so that the woman can quit the cigarette habit.