Which sign typically indicates the onset of preterm labor?

The sign that typically indicates the onset of preterm labor is the presence of regular contractions before 37 weeks of gestation. In the context of pregnancy, contractions are the tightening and relaxing of the uterine muscles, which can occur in relation to true labor or Braxton Hicks (false labor). In the case of preterm labor, these contractions become regular and emerge before the 37-week mark, signaling a potential early birth.

Regular contractions can lead to cervical changes such as dilation or effacement, which are critical indicators used in assessing labor progression. Recognizing these regular contractions as an indication of preterm labor is essential, as timely medical intervention can significantly impact outcomes for both the mother and the unborn child. Identifying the onset of labor accurately ensures appropriate measures can be taken to either manage the delivery or offer interventions aimed at prolonging the pregnancy when possible.

Other options, such as irregular contractions, increased fetal movement, or a decrease in fetal heart rate, do not directly indicate preterm labor. Irregular contractions could be normal Braxton Hicks contractions, increased fetal movement does not signal labor, and a decrease in fetal heart rate could suggest fetal distress, which requires immediate medical attention. Therefore, the presence of regular contractions is the key indicator for the