It May Take Longer to Conceive With High Caffeine Intake
“The research is far from conclusive. But in women, very high caffeine intake, such as over 500 milligrams (mg) per day, has been linked to reduced fertility,” says Alex Robles, MD, a reproductive endocrinologist at Columbia University Irving Medical Center in New York City.
To put that in perspective, 500 mg is equivalent to about five 8-ounce cups of brewed coffee, eight cups of instant coffee, or two and a half energy shots.
Caffeine May Affect Hormone Levels
Caffeine can affect the hormones in your body that are important for conception. In men, caffeine can increase testosterone levels and affect other hormone-related proteins in the blood. It can also change how certain cells in the testicles (called Sertoli cells) function. If Sertoli cells aren’t working properly, sperm production or quality can be affected.
For women, caffeine can block certain hormone receptors, which can interfere with ovulation and the uterus’s ability to receive a fertilized egg. Caffeine may also decrease the body’s ability to convert certain hormones into estrogen, which is important for pregnancy to occur.
Caffeine May Cause Problems With Embryo Attachment
Studies in both women and mice have found that higher amounts of caffeine may make it harder for a fertilized embryo to attach to the uterine wall, says Alexander Kotlyar, MD, a board-certified reproductive endocrinologist and infertility specialist at Genesis Fertility in the New York City area.
An embryo is a fertilized egg that has begun to develop but isn’t fully formed yet. For pregnancy to continue, the embryo must attach successfully to the uterus. According to Dr. Kotlyar, even two cups of coffee a day could affect this process and lead to lower pregnancy rates.
Caffeine May Raise the Risk of Miscarriage
“Some studies show that 200 to 300 mg [of caffeine] per day may be linked to a higher risk of miscarriage,” says Dr. Robles. That’s about two to three 8-ounce cups of brewed coffee per day.
One review of studies found that for every 100 mg of caffeine consumed daily (about one cup of coffee), the risk of miscarriage increased slightly. The same review also found small increases in the risk of stillbirth, premature delivery, and having a baby with low birth weight. But these risks were relatively small, and the research findings aren’t always consistent.
Caffeine May Affect Sperm Health in Men
The research on caffeine and male fertility is mixed and much less clear than for women. “High caffeine intake has been linked to reduced sperm concentration and motility (how well sperm move), possibly affecting testosterone levels and overall sperm health in men,” says Sheeva Talebian, MD, a reproductive endocrinologist at CCRM Fertility of New York.
At least one study suggests that sperm problems may increase with higher doses of coffee, especially after more than three cups per day, says Kotlyar. “Such sperm issues also included damage to the DNA in sperm cells,” he adds.
But other studies have shown no negative effects on sperm quality, and some research even suggests caffeine might help certain cells in the testicles function better. Overall, the evidence is inconclusive, and more research is needed to understand the effects of caffeine on male fertility.
