When the fetus descends into the pelvic cavity. In first-time mothers, usually occurs two to four weeks before delivery; women who have already givenbirth usually don't lighten until they begin labor.
Also called ‘engagement', is the repositioning of the baby lower in the pelvis, sometimes referred to as ‘dropping'. This can occur up to several weeks before the onset of labor.
This occurs when a fetus positions itself lower in the pelvic cavity during the last few weeks of pregnancy.