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.
Can having sex trigger labor? No, not if you have a normal, low-risk pregnancy. Sexual stimulation or orgasm cannot start labor or cause a miscarriage. While orgasm may cause mild uterine contractions (as can nipple stimulation and the prostaglandins in semen), the contractions are generally temporary and harmless.