Causes of Decreased Fetal Movement in the Third Trimester

For a mom-to-be, a baby's kicks and wiggles during late pregnancy are not only a source of joy and excitement, but also a sign of the baby's well-being. That's one of the reasons that, starting in the third trimester, many doctors and midwives advise pregnant women to do "kick counts" to keep track of how active their babies are-- or aren't. When a baby starts moving significantly less than average in the third trimester (less than five perceivable kicks per hour), it could be a sign that something is wrong. One study found that decreased fetal movement in the third trimester was associated with a much higher risk of very serious problems, including stillbirth, so it's important to see your doctor or midwife as soon as possible if you've noticed fewer kicks than usual. Only a thorough check-up can find out exactly why your baby is getting sluggish, but here are some of the possible reasons for decreased fetal movement in the third trimester:
You simply aren't noticing the kicks as much.
As you get further into the third trimester, your amniotic fluid levels decline a little and your baby is cramped tighter into your womb. He might also be in a position that makes it harder to feel his kicks, because the placenta is absorbing a lot of the impact. Combine that with a busy or high-stress day, and you may have a perfectly active baby whose acrobatics are simply going unnoticed.
You're hungry.
If you've skipped a meal (not a good idea ever, but especially when you're pregnant!) you and your baby might be experiencing low blood sugar, which could make you both feel sleepy and groggy. During the third trimester, low blood sugar could cause your baby to be sluggish and you may feel less fetal movement. Many doctors advise drinking a glass of juice to see if it increases the number of kicks you feel..

The baby is napping. 

Just like newborns, unborn babies spend a significant amount of their time sleeping. If you've noticed decreased fetal movement for a relatively short period of time, like a couple of hours, it's entirely possible that your baby's just sleeping. You may be able to wake him by playing loud music or sitting still for a long time (since the movement of walking tends to rock unborn babies to sleep).

You have a placental abruption.
This is one of the more serious possible causes of decreased fetal movement in the third trimester. A placental abruption occurs when the placenta actually detaches from the wall of your womb, making it so your baby can't get the nutrition and oxygen he needs. Depending on how far along you are, this may need to be treated with surgery or inducing labor, and time is of the essence.
Your baby isn't getting enough oxygen.
There are many things that can cause a baby's oxygen levels to plummet in the womb, and decreased fetal movement is often the first sign. There may, for example, be a knot or kink in the umbilical cord. Untreated, low oxygen, or fetal hypoxia, can cause brain damage or even death in an unborn baby, so it needs to be evaluated and treated quickly.
The worst-case scenario. 
It's every parent's worst nightmare, and it's the reason that it's so important to call your doctor or midwife if you notice a dip in fetal movements in the third trimester. Occasionally, a dramatic drop in the amount of movement you feel could be a sign that your baby is dying or, worse, has already died. There are many possible causes of this terrible complication, but many of them could be prevented by seeing a doctor quickly if something seems to be wrong.
If you've noticed a decrease in fetal movements in the third trimester, don't delay in having yourself and your baby checked to make sure that everything is okay. While it's entirely possible that your baby's sluggishness is nothing to worry about, it's not worth the very serious risks of ignoring this warning sign for too long. Always defer to expert judgment when dealing with any complication or warning sign during pregnancy.