Breast engorgement and nausea with occasional vomiting may also be noted. The corpus luteum in the ovary is stimulated by hCG to continue secreting high levels of estrogen and progesterone to maintain the pregnancy. Pregnancies are usually dated in weeks, starting from the first day of the last menstrual period. Thus, if the patient's periods were regular and if ovulation occurred on day 14 of the cycle, obstetric dates are about 2 wk longer than embryologic dates. If the patient's periods are irregular, the difference is more or less than 2 wk.
Pelvic examination detects uterine enlargement compatible with pregnancy.
The cervix is softer, and the uterus is irregularly softened and enlarged. The cervix usually becomes bluish to purple, apparently because blood supply to the uterus is increased. Blood or urine tests are usually positive. Thus, pregnancy can be diagnosed several days after conception. During the first 60 days of a normal single pregnancy, hCG levels double about every 2 to 3 days, rising exponentially.