Want to Have a Baby? Mind Your Alcohol

June 14, 2021 – Most women know that drinking alcohol during pregnancy can endanger the fetus before they know they are pregnant and that there is no set safe amount during pregnancy.

What women may not know is that even moderate drinking in the middle and last half of the menstrual cycle can reduce the chance of successful conception.

According to a new study of drinking patterns and hormone levels at different monthly stages, moderate intake of alcohol (3-6 drinks per week) and heavy intake (more than 6 per week) during the post-ovulation phase of a woman’s cycle can disrupt the delicate hormonal sequence required to conceive. The researchers also found that heavy drinking earlier in a woman’s cycle, during ovulation, can also disrupt conception.

The message? If you want a baby, don’t wait until that long-awaited missed period to drink less.

“The take home message from our study is that if you want to get pregnant, have no more than one drink a day at any time during your menstrual cycle, and less than half a drink during ovulation and after ovulation in the implantation period,” said lead author Kira C. Taylor, PhD, an associate professor of epidemiology and population health at the University of Louisville in Kentucky.

“Alcohol’s impact on [the likelihood of conception] has been suspected since the 1990s but has not been well studied,” says Nishath A. Ali, MD, an assistant professor of obstetrics and gynecology at Baylor College of Medicine in Houston. “Moderate and heavy drinkers generally take longer to conceive and are at greater risk of needing an infertility evaluation,” she says.

Women undergoing fertility treatments such as in vitro fertilization are already advised to drink less.

Published June 9 in the journal Human reproduction, the study, which began in 2017, looked at alcohol and fertility — that is, the chance of getting pregnant in a single menstrual cycle. It analyzed data from 413 women, ages 19 to 41, who completed daily diaries about alcohol intake, including the number of drinks and type (beer, wine or liquor) for a maximum of 19 months of follow-up. Participants were primarily white, non-Hispanic, and married with some college education.

The women submitted monthly urine samples to determine pregnancy status, and their monthly cycle phases were calculated using a calendar-based method and compared between drinkers and non-drinkers.

During the study, 133 women became pregnant, and outcomes showed an effect of alcohol – the more alcohol a woman drank, the less chance she had of getting pregnant. “Among heavy drinkers, the probability of becoming pregnant was 27.2%, which rose to 41.3% among non-drinkers. Light and moderate drinkers both had about a 32% chance of getting pregnant,” says Taylor.

When the researchers looked at the effect of drinking alcohol during different phases of the menstrual cycle, they found that moderate and heavy drinking in the post-ovulation phase reduced the chance of conception by almost half (44% and 49%, respectively) %), compared to non-drinkers. There has also been a suggestion that heavy drinking before ovulation is also linked to reduced likelihood of conception.

What about binge drinking? In particular, each extra day of excessive intake over a short period was associated with a 19% reduction in conception around the time of ovulation and between ovulation and menstruation. But it didn’t seem to have an effect early in the cycle, before ovulation.

The researchers also found that the type of alcoholic drink did not change the results.

“In addition, the study showed that menstrual cycle lengths were similar for women in each drinking category, suggesting that drinking does not affect the hormones that regulate cycle length,” said Christine Metz, PhD, a professor at the Feinstein Institute. for Medical Research in Manhasset, NY.

The authors think that part of the alcohol-conception connection may be disruptive changes in steroid hormones, particularly a surge in estradiol, a form of estrogen.

“The increase in estrogen can lead to irregular cycles, delayed ovulation or anovulation. So couples can try to conceive at the wrong time in terms of ovulation,” says Taylor. “An increase in estrogen can also have an impact on the timing of the window of opportunity in the uterine lining for implantation after conception.”

Experts aren’t exactly sure how a poorly timed rise in estradiol can affect the chance of conception. Although not clearly understood, it appears that the timing of heavy drinking can not only suppress ovulation, but also suppress the ability to sustain an early pregnancy, Ali notes.

And men aren’t off the hook either — their testicles can also be affected by booze. “Heavy alcohol consumption is associated with abnormalities in gonadal function in men, including a reduction in serum testosterone and reduced sperm counts,” says Ali.

One caveat about the new data, the authors say, is that only 20% to 25% of women in the study’s groups actually tried to get pregnant, when such a study should ideally only include women who plan to get pregnant. To touch.

The study also did not look at the influence of male partners’ drinking, and the data relied on self-reporting by participants, which depends on accurate recall. Still, the study points to another compelling reason to cut back on alcohol before you start trying to conceive.

The bottom line, says Ali: “Lifestyle interventions are important for both members of a couple planning a pregnancy.”

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