A new research study has found and identified a chemical pathway by which a mother's smoking before and after pregnancy might reduce her daughter's fertility by as much as two thirds. As we all know, cigarette smoking during pregnancy is a definite no-no, and has been shown in retrospective studies to affect the fertility of a woman's offspring. But this would be the first study that attempted explanation of the biology behind this effect, according to the Canadian scientists behind the research. The research was performed by a team from the Samuel Lunenfeld Research Institute at Mount Sinai Hospital in Toronto that studied and investigated on the impact of polycyclic aromatic hydrocarbons (PAH), a byproduct of smoking, on mouse fertility.
The study included injections of a low dose mixture of PAH to three groups of female mice. One group received PAH before conception and again when they were providing milk for their pups, while one group received PAH only before conception, and the third group received PAH only during lactation. A fourth control group did not receive PAH but were mated at the same time as others. The total amount of PAH given to each mouse over the three-week injection cycle was equivalent to 25 packs of cigarettes, according to researchers. The exposed mice did not have fewer pups in their own litters, but when the researchers investigated on the number of eggs in their female offspring, they found about 70 percent fewer follicles available to produce eggs.
According to the lead researcher Dr. Andrea Jurisicova, the mother (mice in this case), exposed to PAHs—environmental pollutants found in cigarette smoke, car exhaust, smoke produced by fossil fuel combustion, as well as in smoked food—before pregnancy and/or during breastfeeding, but not during pregnancy, can cause a reduction in the number of eggs in the ovaries of their female offspring by two-thirds. This limits the window in which the daughter will be able to reproduce.
The new data provides biological support for epidemiological results, such as the previously observed reduction in fertility among daughters of smoking women. According to Dr. Norman Edelman of the American Lung Association, “if we do our job right and these results get good press thus this data could remind women of what they are doing to their unborn fetuses.” Dr. Amos Grunebaum of New York Weill Cornell Medical Center also added that this is an interesting study, but does not add much, since other studies have also shown similar outcomes. The key point here is that women should quit smoking before they even think of getting pregnant.
Although the findings do not define the length of time between quitting smoking and healthier fertility in offspring, Jurisicova noted that previous studies have shown that women who smoke have better results with “in vitro” fertilization one year after they quit smoking. The mice in the current study conceived up to two weeks after their final PAH injection, which is approximately equivalent to three menstrual cycles in women. More research is still needed for this, but mothers should be aware of the dangers that smoking can bring to their future offspring even after knowing this specific research study.