What are the chancesof getting pregnant from Precum?

Hi,
Welcome to ehealthforum,
If the intercourse is during your fertile days (with fertile mucus present) or closer to your ovulation time, chances of pregnancy are possible with pre-cum. Intercourse during periods/menstrual bleeding (with or without ejaculation) will not result in pregnancy as the chances of egg being present is nil. If you have been sexually active without protection after finishing with periods, chances of pregnancy are possible (since you become closer to your fertile days/ovulation time after finishing with periods). The symptoms that you describe (nausea, vomiting, tight feeling lower abdomen, abdominal cramps, constipation, tender chest) could be few of early symptoms suggestive of pregnancy. Wait and watch for your periods. Look out for development of any other new symptoms if pregnancy is suspected. If periods do not start within 10 days of expected period dates, or if you get abnormal periods, or if you suspect chances of pregnancy, consider visiting your doctor/gynecologist at the earliest for thorough examination (to confirm pregnancy related changes/signs in body) and blood/serum HCG level test (to confirm/rule out pregnancy accurately). Be in regular monitoring and follow-up with your treating doctor/gynecologist and report any new/abnormal symptoms immediately. Take adequate rest. Drink plenty of water. Maintain healthy diet.
Take care.