Getting pregnant can be difficult for several reasons. A woman only ovulates once per menstrual cycle, releasing an egg that must be fertilized within 12-6 hours. The timing of intercourse in relation to ovulation is important for success. Male sperm quality can also impact chances of fertilization, and is negatively impacted by factors like heat, tight underwear, and excessive ejaculation. Achieving pregnancy requires having intercourse near the time of ovulation, rather than frequent intercourse throughout the cycle, to allow the sperm to be present when the egg is released. Charting basal body temperature and other signs can help predict ovulation and maximize chances of conception. Lifestyle factors like smoking, drinking, poor diet, and drug use also reduce fertility for both males