The 38th week of pregnancy often brings excitement and anxiety as the due date approaches. Prenatal appointments frequently include a cervical check, an internal exam performed by a healthcare provider to assess preparation for birth. Receiving a specific measurement, such as 2 centimeters dilated, prompts the question of how much longer the wait will be. Understanding this requires shifting focus from a precise timeline to the body’s readiness for labor.
Understanding Cervical Measurements
A late-term cervical examination assesses three distinct measurements describing the condition of the cervix and the baby’s position.
Dilation
Dilation refers to how open the cervix is, measured in centimeters from 0 to 10. Ten centimeters represents full dilation, the point at which the cervix is wide enough for the baby to pass through the birth canal.
Effacement
Effacement describes the thinning and softening of the cervix, measured in percentages from 0% to 100%. Before labor, the cervix is usually thick, measuring about three to five centimeters in length, or 0% effaced. The cervix must thin completely to 100% effacement before full dilation can occur.
Fetal Station
Fetal station indicates how far the baby’s head has descended into the mother’s pelvis. This is measured relative to the ischial spines, using a scale from -5 to +5. A zero station means the baby’s head is engaged and level with these spines. Negative numbers mean the head is higher up, and positive numbers indicate descent toward the vaginal opening.
What 2 cm Dilation at 38 Weeks Actually Means
A measurement of 2 cm dilation at 38 weeks confirms that the body is making progress, but it is a snapshot, not a countdown to delivery. Dilation is non-predictive of when active labor will begin, as some women remain at 2 cm for days or weeks before contractions become strong and regular. Conversely, others may be completely undilated one day and deliver within hours.
The significance of 2 cm dilation differs based on whether a woman has delivered before. For a first-time mother (primiparous), the cervix tends to efface (thin) significantly before it begins to dilate (open). A multiparous woman, one who has had previous full-term pregnancies, often begins dilating earlier because the cervix does not always fully close after the previous birth.
The combination of dilation, effacement, and fetal station provides a more comprehensive picture of cervical readiness than dilation alone. For instance, a cervix that is 2 cm dilated, 80% effaced, and at a zero station suggests greater readiness than one that is 2 cm dilated, 20% effaced, and at a -3 station.
Other Indicators of Labor Readiness
While the internal exam offers data, the body provides external clues that labor is drawing nearer.
Lightening
One common sign is “lightening” or fetal drop, which occurs when the baby settles lower into the pelvis. This process can happen weeks or hours before labor. This descent may lead to increased pelvic pressure and a greater need to urinate, even as it offers relief from pressure on the diaphragm, making breathing easier.
Mucus Plug and Bloody Show
Another event is the loss of the mucus plug, sometimes accompanied by a pink or brown-tinged discharge known as “bloody show.” The mucus plug seals the cervix during pregnancy, and its expulsion indicates cervical changes, though it may precede labor by several days or weeks.
Braxton Hicks Contractions
Many women also experience an increase in Braxton Hicks contractions. These are irregular uterine tightenings that do not progressively increase in intensity or frequency. These practice contractions help ripen the cervix but are not the sustained, rhythmic contractions of true labor.
The Transition to Active Labor
The true indicator of a shift from pre-labor readiness to established labor is a change in the contraction pattern. Early labor involves manageable, inconsistent contractions, allowing the mother to rest, walk, and talk through them. Active labor is characterized by contractions that become progressively longer, stronger, and closer together.
These true labor contractions are rhythmic and persistent; they do not stop when a person changes position or activity, unlike Braxton Hicks contractions. Healthcare providers advise calling the hospital when contractions follow the “5-1-1” pattern for a first-time mother: contractions five minutes apart, lasting one full minute, and maintaining this pattern for one hour.
Certain circumstances warrant an immediate call to a healthcare provider, regardless of the contraction pattern. These include a rupture of membranes (water breaking) or any instance of significant bright red vaginal bleeding. A decrease in fetal movement also requires urgent evaluation, as fetal activity measures the baby’s well-being.