| Braxton Hicks contractions | |
| Synonyms: | Practice contractions, false labor |
Braxton Hicks contractions, also known as practice contractions or false labor, are sporadic uterine contractions that may start around six weeks into a pregnancy.[1] However, they are usually felt in the second or third trimester of pregnancy.[2]
Braxton Hicks contractions are often confused for labor. Braxton Hicks contractions allow the pregnant woman's body to prepare for labor. However, the presence of Braxton Hicks contractions does not mean a woman is in labor or even that labor is about to commence. Another common cause of pain in pregnancy is round ligament pain.
Table 1. Braxton Hicks contractions vs. true labor
| Braxton Hicks Contractions | True Labor Contractions | ||
| Cervical Dilation | Do not cause cervical dilation | Cause cervical dilation | |
| Frequency of Contractions | The timing between contractions is not regular | The timing between contractions is regular and the contractions begin to occur closer together over time | |
| Strength of Contractions | They are not usually very strong | They become stronger over time | |
| Length of Contractions | Length is uncertain | The contractions last between 30–90 seconds and grow longer as labor progresses | |
| Location of Pain | Usually the pain is in the front of the abdomen | The pain starts in the back and moves around to the front. | |
| Change with Movement | Contractions may stop if the woman moves | Contractions will continue and/or become stronger regardless of the woman's movements |
Although the exact causes of Braxton Hicks contractions are not fully understood, there are known triggers that cause Braxton Hicks contractions, such as when a pregnant woman:[3]
There are two thoughts for why these intermittent uterine muscle contractions may be occurring. The first is that these early “practice contractions” could be helping to prepare the body for true labor by strengthening the uterine muscle. The second is that these contractions may occur when the fetus is in a state of physiological stress, in order to help provide more oxygenated blood to the fetal circulation.
The determination of Braxton Hicks contractions is dependent on the history and physical assessment of the pregnant woman's abdomen, as there are no specific imaging tests for diagnosis. The key is to differentiate Braxton Hicks contractions from true labor contractions (see Table 1 above).
Most commonly, Braxton Hicks contractions are weak and feel like mild cramping that occurs in a localized area in the front abdomen at an infrequent and irregular rhythm (usually every 10-20 minutes), with each contraction lasting up to 2 minutes. They may be associated with certain triggers and can disappear and reappear; they do not get more frequent, longer, or stronger over the course of the contractions. However, as the end of a pregnancy approaches, Braxton Hicks contractions tend to become more frequent and more intense.
On a physical exam, some uterine muscle tightening may be palpable, but there should be no palpable contraction in the uterine fundus and no cervical changes or cervical dilation. Braxton Hicks contractions do not lead to birth.
More concerning symptoms that may require assessment by a healthcare professional include:
Although there is no specific medical treatment for Braxton Hicks contractions, some alleviating factors include:
Braxton Hicks contractions are named after John Braxton Hicks, the English physician who first wrote about them in Western medicine.[4] In 1872, he investigated the later stages of pregnancy and noted that many pregnant women felt contractions without being near birth. He examined the prevalence of uterine contractions throughout pregnancy and determined that contractions that do not lead to labor are a normal part of pregnancy.