March 18, 2004 -- Women trying to become pregnant may want to avoid a popular class of pain relievers and arthritis drugs.
The warning comes in a brief editorial in the March issue of Fertility and Sterility. Robert J. Norman, MD, and Ruijin Wu, MD, of the University of Adelaide, in South Australia, point out several studies showing that newer anti-inflammatory pain killers -- called Cox-2 inhibitors -- may interfere with several stages of a woman becoming pregnant. These pain relievers include Bextra, Celebrex, and Vioxx.
But they note there's no scientific proof at this point that Cox-2 inhibitors actually make it harder for a woman to become pregnant.
Norman and Wu warn that there's good evidence that the pain relievers can affect ovulation, fertilization, and even labor. They also note that older anti-inflammatory pain relievers, such as ibuprofen, appear to have the same effects. Both older and newer anti-inflammatory pain relievers are known collectively as NSAIDs (nonsteroidal anti-inflammatory drugs). Another common pain reliever, Tylenol, is not an NSAID and these findings do not apply to this drug.
"Women seeking to become pregnant should quit using Cox-2 inhibitors or NSAIDs for at least a week or two before attempting to become pregnant," Norman tells WebMD. "There are concerns about Cox-2 inhibitors in pregnancy, largely due to the effect on the fetus."
Cox-2 inhibitors were created to help decrease some of the side effects associated with older anti-inflammatory pain relievers, such as stomach irritation and bleeding. Both types of pain relievers block the production of chemicals called prostaglandins, which cause inflammation. However, prostaglandins play a major role in ovulation and follicle maturation.
Norman and Wu note that there's increasing evidence that Cox-2 inhibitors impair fertilization, implantation of the fertile egg in the uterus, and continuation of pregnancy. However, they stress that more research is needed to define the exact effects these pain relievers have at various stages of conception and pregnancy.
"Cox-2 inhibitors or NSAIDs, all of those can potentially affect or diminish ovulation," agrees Celia Dominguez, MD, a reproductive endocrinologist at Emory University in Atlanta. "That is the thinking behind it, but this is not very strong science. It is just the concept that ovulation is associated with prostaglandin that makes people worry."
The Cox-2 inhibitors Bextra, Celebrex, and Vioxx offer substantial relief to people who need these pain relievers. Norman suggests that women should talk to their doctors about whether to continue taking these medications before and during pregnancy.
"Women taking Cox-2 inhibitors may take longer to become pregnant. If there is a delay in fertility they should stop these drugs," Norman says. "If women are already pregnant, alternative drugs should be discussed with their doctor."
Dominguez agrees with this advice.
"When trying to get pregnant, avoid Cox-2 inhibitors," she says. "And during pregnancy, we always advise women to avoid all medications as much as possible."