Important - we don't eat cows. We eat steer. Cows have been bred over the decades and centuries to give birth and milk, not to yield meat. That's important, because some cows are heavier than their steer counterparts (Holsteins, for example).
Also very dangerous is inducing a miscarriage by taking strong medications prescribed for other ailments and many of the ways to induce a miscarriage can actually end in loss of life or other very serious consequences.
Actually, you can enjoy a brew, but you need to watch quantity. Too much caffeine (also found in tea, cola and chocolate) can increase your risk of miscarriage. The NHS recommends a limit of 200mg a day of caffeine, the equivalent of two mugs of instant coffee.