Hegar’s sign is a softening of the lower part of the uterus that occurs in early pregnancy, typically detectable between weeks 6 and 12. During a pelvic exam, a clinician can feel that the narrow segment connecting the main body of the uterus to the cervix has become noticeably soft and compressible. It’s classified as a probable sign of pregnancy, meaning it strongly suggests pregnancy but doesn’t confirm it on its own.
What Happens in the Uterus
The uterus has three main sections: the body (the large upper portion), the isthmus (a short, narrow transition zone in the middle), and the cervix (the lower opening). In early pregnancy, rising hormone levels increase blood flow to the uterus and cause its tissues to retain more water. The isthmus responds to these changes more dramatically than the surrounding structures, becoming so soft that it feels almost like a gap between the firmer uterine body above and the still-firm cervix below.
A positive Hegar’s sign is identified when this lower uterine segment feels distinctly softer than both the body above it and the cervix below it. The softening begins within the first six weeks of pregnancy and becomes most noticeable during the rest of the first trimester.
How It’s Detected
Hegar’s sign is found during a bimanual pelvic exam, where the clinician places two fingers inside the vagina and the other hand on the lower abdomen. By gently pressing these two hands toward each other, the examiner can feel the consistency of the uterine isthmus between them. When the isthmus is soft enough that the two hands nearly meet, as though the middle section of the uterus is almost compressible between the fingers, that’s a positive Hegar’s sign.
The timing matters. The sign is most reliably detected between 6 and 12 weeks of gestation. Before 6 weeks, the softening may not be pronounced enough to notice. After the first trimester, the entire uterus enlarges and firms up as pregnancy progresses, making this specific finding less distinct.
Probable vs. Positive Signs of Pregnancy
In obstetrics, signs of pregnancy fall into three categories: presumptive, probable, and positive. Presumptive signs are things you feel yourself, like nausea or breast tenderness, that could have many explanations. Probable signs are physical findings a clinician can observe that strongly point to pregnancy but aren’t absolute proof. Positive signs are definitive, like hearing a fetal heartbeat or seeing the fetus on ultrasound.
Hegar’s sign falls into the probable category. It is a non-specific indication of pregnancy, meaning that while the softening of the isthmus is characteristic of early pregnancy, other conditions that increase blood flow to the pelvic area could theoretically produce similar tissue changes. On its own, it suggests pregnancy but doesn’t rule out other explanations entirely.
Why It’s Less Common in Modern Practice
Before home pregnancy tests and ultrasound existed, physical findings like Hegar’s sign were among the best tools clinicians had to identify early pregnancy. A bimanual exam could detect the characteristic softening weeks before a pregnancy would be otherwise obvious. Other similar signs from the same era include Chadwick’s sign (a bluish discoloration of the cervix and vagina) and Goodell’s sign (softening of the cervix itself).
Today, urine pregnancy tests can detect pregnancy hormones before Hegar’s sign even appears, and transvaginal ultrasound can visualize a gestational sac as early as 4 to 5 weeks. Blood tests measuring pregnancy hormone levels provide even more precise information. These tools have largely replaced the bimanual exam as a method of confirming pregnancy, though clinicians still perform pelvic exams in early pregnancy for other reasons, like checking the size of the uterus or screening for abnormalities.
Hegar’s sign remains a standard topic in medical and nursing education because it illustrates how pregnancy hormones physically transform uterine tissue. Understanding it helps clinicians interpret what they feel during routine pelvic exams, even if they no longer rely on it as a primary diagnostic tool.