Pregnancy symptoms can begin as early as six to 12 days after conception, according to WebMD, when some women may experience cramping, bleeding or both symptoms from the embryo implanting into the uterus. Ovulation and conception happen 14 days before a missed period, so a woman on a 28-day cycle may get symptoms as early as 20 days after the beginning of her last menstrual period.
A white, milky discharge is another symptom of early pregnancy and is due to the thickening of the uterine lining. Around the time of implantation, a woman may also notice that her breasts are sore, swollen or changing in other ways. This soreness is sometimes more pronounced during a first pregnancy than with subsequent pregnancies.
About a week after conception a woman has a spike in her progesterone levels that could make her feel unusually tired. According to the Mayo Clinic, the symptoms of nausea and vomiting can start as early as three weeks after conception. Increased urination and food cravings or aversions are also early pregnancy symptoms. Although many of these symptoms appear before a missed period for some women, for others they may not start until six to seven weeks or not occur at all, according to AboutHealth.