Some research suggests that Mucinex (or more specifically the active ingredient contained in Mucinex, guaifenesin) may help increase fertility by keeping the cervical mucus thin around the time of ovulation, which ensures sperm can travel freely through the cervix and helps with sperm survival. An increase in fertility can help increase your chances of becoming pregnant. Women with hostile mucus as the only cause of their infertility are the ones most likely to benefit from guaifenesin treatment.