Couples trying to have a baby should have sex every day, according to a study by Dr. David Greening, an Australian infertility physician. Daily intercourse improves sperm quality because frequent ejaculation reduces the amount of time sperm is exposed to molecules inside the testicular ducts, known as reactive oxygen species, that may cause damage. Greening recommends that couples have sex every day for a week before the woman begins ovulation in order to maximize their chances of getting pregnant.