lightening
The descent of the fetal presenting part into the pelvis, typically occurring 2-4 weeks before labor in first pregnancies.
Full Definition
Lightening, also known as 'dropping,' describes the physiological process where the fetal head or presenting part descends into the maternal pelvis in preparation for delivery. This occurs approximately 2-4 weeks before the onset of labor in primigravid women, but may not occur until labor begins in multiparous women. The descent relieves pressure on the diaphragm, allowing easier breathing, but increases pressure on the bladder and pelvic floor. Healthcare providers assess lightening through abdominal palpation and measurement of fundal height.
Usage
Usage note: Often confused with engagement, which is a more precise medical measurement.
In Context
- "The patient experienced lightening at 37 weeks, with improved respiratory comfort but increased urinary frequency." — Labor and delivery notes
- "Fundal height decreased from 38cm to 35cm, indicating lightening has occurred." — Prenatal examination record