Lightening During Pregnancy as an Early Sign of Labor

Lightening during pregnancy actually describes the baby engaging in the pelvis before vaginal birth. It is thus named because as the baby moves down from under the rib cage, the mother may feel a sense of relief as her rib cage expands more easily allowing her to draw deeper breaths and eat without feeling full quickly.

Although lightening may eliminate some uncomfortable symptoms, it may increase others. Some women feel more pressure on their bladders which causes them to urinate more frequently while others have a perpetual feeling that the baby is about to fall out. These feelings result from the added pressure that the baby's head is placing on the rectum and pelvic floor.

Lightening cannot be directly linked to indicating that labor will start within a certain window, but it usually occurs up to two weeks before labor in 65% of first-time moms. Although it can't pinpoint the beginning of labor, it is a sign that things are headed in the right direction.

It should be noted, however, that lightening usually occurs in a first-time pregnancy whereas in subsequent pregnancies, the baby may not drop until labor has officially begun. It can be a gradual process that happens over several days or weeks or it can be an all-or-nothing event.

The degree of lightening during pregnancy corresponds to the level of the baby's head in relation to the mother's pelvic girdle. This is referred to as the baby's station. Stations progress from -5 to +5, with -5 meaning that the baby is still floating above the pelvis and +5 meaning that the head is crowning. The baby is said to be fully engaged when at 0 station.

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Page Last Modified by Catherine Beier, MS, CBE