Positive Signs:
• Auscultation of the fetal heart
• Perception of fetal movement by an experienced examiner
• Demonstration of a fetus by ultrasound: intrauterine sac visible by 5 weeks amenorrhea, fetal pole at 6 weeks, fetal cardiac activity at 7-8 weeks (transvaginal ultrasound)
• Positive pregnancy test: presence of β-hCG; the serum is positive by 9 days post conception; plasma levels double every 48 hours to a maximum at 8-10 weeks gestation when it plateaus (if there are abnormalities in how the β-hCG is rising, consider missed abortion or ectopic pregnancy; if the β-hCG is higher than expected consider twins or molar pregnancy)
• β-hCG may also be detected in urine (28 days after last menstrual period)