A recent study revealed that even moderate alcohol intake in the second half of the menstrual cycle can negatively affect fertility. Published in the medical journal Human Reproduction, this research uniquely analyzed alcohol consumption across the distinct phases of a single menstrual cycle, rather than comparing fertility and alcohol use in general.
Who Was Studied and How?
The study followed over 400 women aged 19 to 41, tracking up to 19 menstrual cycles per participant. They kept detailed diaries of how much and what types of alcohol they consumed. Each cycle, they also provided two urine samples to monitor pregnancy.
Heavy drinkers were those having more than six alcoholic drinks per week. Moderate drinkers consumed three to six drinks weekly. Excessive drinking was defined as averaging four or more drinks per day. One drink counted as a can of beer, 150 ml (5 fl oz) of wine, or a shot of spirits.
Researchers also gathered info on factors that might influence results, like age, medical history, smoking, obesity, birth control use, and pregnancy intentions.
Dr. Taylor, one of the lead researchers, shared:
“We found that heavy drinking at any stage of the menstrual cycle is significantly linked to a lower chance of conception.”
This means any amount or type of alcohol lowers your chances of getting pregnant. The effect was especially clear during the luteal phase—the last two weeks of the menstrual cycle before bleeding starts.
“This is the implantation phase, where not only heavy but even moderate drinking is strongly linked to reduced chances of conception.”
How Much Is Too Much?
The numbers were striking: women who drank moderately or heavily during the luteal phase reduced their pregnancy chances by 44% compared to those who abstained.
Even more concerning were women who drank heavily around ovulation—about day 14 of the cycle—who saw a 61% drop in conception odds.
Excessive drinkers’ chances dropped an additional 19% if they drank during the luteal phase, and 41% during ovulation. The study found no difference in effects between types of alcoholic drinks.
Alcohol Isn’t Birth Control
It’s important to note that drinking alcohol doesn’t make pregnancy impossible. Assuming a healthy, average woman has about a 25% chance of conceiving each cycle, that means 25 out of 100 women will get pregnant right away. For moderate drinkers, this drops to 20 women, and for heavy drinkers, 11—but it’s never zero.
The researchers emphasize that their study doesn’t prove alcohol directly lowers fertility or that women drinking during the luteal phase don’t need contraception. Instead, it shows a clear link between alcohol use and fertility that varies across cycle phases.
Experts suggest alcohol may disrupt ovulation, possibly preventing an egg from releasing during that cycle. If no egg is released, there’s nothing for sperm to fertilize.
Another possibility is that even if fertilization happens, alcohol might interfere with the embryo’s ability to properly implant in the uterus, preventing a healthy pregnancy from developing.
