What is lightening?
For the better part of your pregnancy, your baby will be positioned upright for his or her development. However, at the end of your third trimester, your body will start naturally preparing for birth, and your baby will “drop” into the birthing position. This is also called lightening or head engagement. While this is certainly a sign that your first pregnancy is imminent, you don’t need to rush out to the door for delivery as soon as your baby drops. If your due date is still one or two weeks away, there’s a good chance your baby won’t come out until then. For subsequent pregnancies, your baby won’t drop until labor begins. As always, every woman’s body is different, and it’s impossible to predict exactly when lightening will occur.
Can you feel when the baby drops?
Many women say that they can feel their baby drop. As you might imagine, the change in your baby’s position will cause some of your pregnancy complaints to change. After nine months in the same spot, your baby’s new spot might make some of your symptoms worsen while others improve. If you’ve been struggling with shortness of breath and heartburn, your baby dropping will alleviate these symptoms because he’ll be farther from the affected organs. However, you might need to urinate more frequently, and you might experience more pelvic pain after the drop. Luckily, the drop indicates that you only have a few weeks left.
Your doctor will give you a check-up after the drop to make sure your baby is in the proper position. Studies show that an intrapartum translabial ultrasound is a simple test that can show your doctor what position your baby is in and the angle in which he’ll start his descent. He’ll likely assess your labor station with three stages. In station -3, the head is still above the pelvis. In station 0, the head is at the bottom of the pelvis during labor, and in station +3 your baby is crowning. Knowing how the baby is positioned ahead of time can prevent complications associated with breech birth, and it can also cue your doctor in to the signs of preterm labor in advance.
Once your baby drops, you might also notice a change in how your baby bump looks. It is the first clear sign that motherhood is imminent, so take a moment to appreciate the last few weeks of your pre-mom lifestyle.
Source: B Tutschek et al: A Study Of Progress Of Labour Using Intrapartum Translabial Ultrasound, Assessing Head Station, Direction, And Angle Of Descent JOG: An International Journal of Obstetrics & Gynecology Volume 118, Issue 1, pages 62–69, January 2011