July 2, 2002 -- Men who smoke lower their chances of becoming fathers, even when using artificial means to help their partners become pregnant. A new study shows the chances of an assisted reproductive technique failing are two to three times higher among smoking men compared with nonsmokers.
"We would like to stress to couples that smoking not only affects their own health, but under the special circumstances of assisted reproduction, it represents a needless risk to women undergoing ... hormone stimulation, as well as an unnecessary financial burden," says researcher Michael Zitmann, MD, of the Institute of Reproductive Medicine in Münster, Germany, in a news release.
Zitmann presented his findings today at the European Society of Human Reproduction and Embryology annual conference in Vienna.
The researchers found smoking was the only significant factor that predicted whether an assisted reproduction technique, such as in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI), succeeded or failed.
IVF involves removing eggs and sperm, fertilizing the eggs in the lab, and placing a fertilized egg in the woman's uterus. With ICSI, a single sperm is injected into the egg in the lab to fertilize it, and then the fertilized egg is implanted in the uterus.
The researchers looked at 301 couples who underwent either IVF or ICSI. In the IVF group, 18% of women with smoking partners became pregnant, compared with 32% of women with nonsmoking partners. Results among the ICSI group were similar. Only 22% of the women whose partners smoked became pregnant, vs. 38% of the women with nonsmoking partners.
Researchers say smoking alters the DNA of sperm, and they say this hampers the development of the embryo in both methods.
The researchers also found that smoking affected the number of eggs retrieved from the ovaries. If the woman smoked, the average number of retrievable eggs dropped from 11.7 per menstrual cycle to 9.5. Other factors such as the woman's age also affected this number (the older the woman, the fewer eggs that could be retrieved).
"It can be assumed that quitting smoking will be beneficial to couples undergoing IVF or ICSI, " says Zitmann. "However, we do not know how long the damaging effects of smoking last after quitting."