Chemically, nicotine has been shown to concentrate in cervical mucous and metabolites have been found in follicular fluid and been associated with delayed follicular growth and maturation. Finally, there is some affect on tubal motility because smoking is associated with an increased incidence of ectopic pregnancy as well as an increased spontaneous abortion rate. The total effect of alcohol on fertility is not as well established as with cigarettes and other substance abuse. In one survey, women with high alcohol use reported more menstrual problems and gynecologic surgery. It has been shown to alter estrogen and progesterone levels as well as cause anovulation.
Most chronic alcoholics become amenorrheic.
While the effects of alcohol on fertility are real, it is not clear how much must be consumed to affect fertility, or conversely, how much consumption is safe. In pregnancy, we know that an average of 2 drinks per day or more, or binge drinking of 5 or more drinks at a time can produce fetal alcohol syndrome birth defects. There was no increase with less than 100 grams consumption a week. Not all reports, but many, show that increased caffeine consumption affects the ability to become pregnant and carry the pregnancy. Caffeine clearance from the body is decreased during the luteal phase.