A study looking at links between drinking alcohol and the chance of becoming pregnant suggests that women who want to conceive should avoid heavy drinking
Research has shown that even moderate drinking in the second half of the menstrual cycle is linked to a reduced chance of pregnancy.
The study, published in Human Reproduction, one of the world’s leading reproductive medicine journals, investigated alcohol intake and the probability of conceiving during a single menstrual cycle. It is the first study to look at the different phases of women’s menstrual cycles.
Researchers led by Dr. Kira Taylor, associate professor of epidemiology and population health at the University of Louisville School of Public Health and Information Sciences (Kentucky, USA), analysed data from the Mount Sinai Study of Women Office Workers.
Dr. Taylor said: “We found that heavy drinking during any phase of the menstrual cycle was significantly associated with a reduced probability of conception compared to non-drinkers. This is important because some women who are trying to conceive might believe it is ‘safe’ to drink during certain parts of the menstrual cycle.
Boosting your chance of success
“During the luteal phase, which is the last two weeks of the menstrual cycle before bleeding would start and when the process of implantation occurs, not only heavy drinking but also moderate drinking was significantly associated with a reduced probability of conception.
“At the time of ovulation, usually around day 14 of the cycle, consuming a lot of alcohol – either heavy or binge drinking – was significantly associated with reduced chances of conception.”
Women aged 19 to 41 years were recruited between 1990 and 1994 and followed for a maximum of 19 menstrual cycles. The women completed daily diaries reporting how much alcohol they drank and what type, and they provided urine samples on the first and second day of each menstrual cycle in order to check for pregnancy.
Heavy drinking was defined as more than six alcoholic drinks a week, moderate drinking was three to six drinks a week, and binge drinking was defined as four or more drinks on a single day. The researchers collected information on factors that could affect the results, such as age, medical history, smoking, obesity, use of birth control methods, and intention to become pregnant. Data on 413 women were available for the current study.
Compared to non-drinkers both moderate and heavy drinking during the luteal phase was linked to a reduction in the odds of conceiving by about 44 percent. Heavy drinking during the ovulatory part of the cycle was also associated with a significant 61 percent reduced odds of becoming pregnant. However, the researchers stress these are all estimates and should be treated with caution.
Researchers said the study is not able to show that drinking alcohol causes a reduction in the chances of becoming pregnant, only that it is associated with it. Possible biological mechanisms that might explain the association could be that alcohol intake affects the processes involved in ovulation so that no egg is released during the ovulatory part of the cycle, and that alcohol could affect the ability of a fertilised egg to implant in the womb.
Dr. Taylor said: “This is the first study to examine the effect of alcohol on fecundability during specific phases of the menstrual cycle, using daily data on alcohol and other important factors such as smoking and unprotected intercourse over a period of up to 19 menstrual cycles.”
Limitations of the study included the fact that not all women were trying to conceive; alcohol intake has increased since the time of the study and the women in the study were leaner, on average, than women today; the study used self-reported data and women might under-report their alcohol consumption, and the influence of drinking by male partners was not assessed.
She concluded: “Finally, the results in this study should not be construed to mean that drinking alcohol prevents pregnancy. In other words, alcohol is not birth control. Even if a woman drinks alcohol heavily, if she has unprotected intercourse, she can become pregnant.”
Did you have to change your lifestyle to have fertility treatment? Were you told to lose weight or give up drinking? We’d love to hear your story, email email@example.com.