Pregnancy is most likely to occur when sperm meets an egg during the fertile window, which begins several days before ovulation and ends shortly after it. Ovulation itself occurs when a mature egg is released from the ovary, and this egg remains viable for only about 12–24 hours. Therefore, you can become pregnant during the day of ovulation or within roughly 12–24 hours after ovulation, provided sperm are present. However, the peak fertility period typically occurs in the 1–2 days before ovulation, when sperm survival gives them the best chance of meeting the egg. Sperm can live inside the female reproductive tract for 3–5 days under favorable conditions, which is why intercourse days before ovulation can still result in pregnancy. After the 24-hour window following ovulation closes and the egg is not fertilized, pregnancy cannot occur during that cycle because the egg degenerates and is reabsorbed. Understanding this timing is useful for those trying to conceive or practicing fertility awareness, though it's important to note that ovulation timing can vary between individuals and cycles, making prediction less reliable than commonly assumed.