Aside from the typical morning sickness, a missed period, and unusual food cravings, other symptoms not visible until a doctor performs a gynecological exam may indicate the conception of a baby like Hegar's sign of pregnancy. Named after late-19th-century German obstetrician Ernst Ludwig Alfred Hegar, who first described it, Hegar's sign first becomes noticeable in about four to six weeks after conception, allowing a physician to easily compress the typically hard tissue of the cervical isthmus. This is located at the bottom of the uterus and the top of the vagina, at the cervical opening in an area known as the uterine isthmus. Though this symptom is frequently observed, it does not necessarily mean a woman is pregnant. Conversely, a woman may be pregnant but not show this sign at all during early examinations.

Two signs of pregnancy are actually named after Hegar. According to the Who Named It? Web site, the same doctor is also credited with identifying Hegar's sign II, which is an overall softening of the uterine cavity, also known as the corpus uteri. Named for the doctor as well is the Hegar's dilator and the Hegar's operation, which involves repairing the perineum after childbirth.

According to the WebMD Web site, Hegar's sign is not what leads women to believe they are pregnant. Several other symptoms are more likely to be noticed before a pregnancy test is taken and a gynecologist is visited. These early symptoms of conception include vaginal spotting or discharge, a missed period, morning sickness, swelling breasts, dizziness, constipation, strange dietary cravings, lethargy, increased urination and headaches.

During an examination, a doctor has a few signs to look for that may indicate pregnancy, aside from the customary urine and blood screenings. Appearing as early as six weeks and as late as 10 weeks, another symptom called Chadwick's sign is an overall darkening of the vagina and cervical opening, from pink to bruised-looking. Like Hegar's sign, this can be caused by other conditions besides pregnancy, though. Yet another sign a doctor may look for is named after American gynecologist William Goodell's, who at the end of the 19th century also noticed that a woman's entire cervix often softened as soon as four weeks after conception. This came to be known as Goodell's sign, involving a softening of the entire cervix.