Pregnancy causes a variety of new sensations, including pinching, pressure and pain in the abdomen. Because your baby's head is the largest part of her body, it's also the area most likely to cause noticeable pain. A sharp, low, pinching pain is typically not indicative of a serious health condition, but you should still consult your doctor about the pain. If you experience bleeding or a fever along with the pain, go to the emergency room immediately.
Head Engagement
Toward the end of the third trimester -- usually in the 36th week -- the developing fetus moves lower into the uterus to prepare for delivery, according to pediatrician William Sears in his book "The Pregnancy Book." Pregnant women typically feel as if they have substantially more room to breathe when this happens, but they may also feel pinching and tugging sensations in the uterus. The pain isn't cause for concern and simply indicates that your baby is ready to join the world.
Fetal Movement
Developing babies begin moving as early as 6 weeks into pregnancy, but these movements aren't palpable until the second trimester. Early movements can create a fluttering sensation or make you feel as if you have gas, according to the book "What to Expect When You're Expecting." As the movements grow stronger, they may be painful at times and can create a very sharp, sudden sensation in the uterus.
Tailbone Pressure
In the second and third trimesters, it's common for the fetus's head to rub and even slam against your tailbone. The condition is called coccydynia. The pain can be excruciating and even leave bruises, but the condition won't cause long-term harm to you or your baby. Try applying warm compresses to the area to ease soreness.
Other Causes
Occasionally, pain in the abdomen is merely coincidental to pregnancy. Any sharp, sudden pain that quickly gets worse should immediately be investigated by your doctor. You could have an ovarian cyst or appendicitis. If you feel pain during early pregnancy, the cause is unlikely to be caused by your baby's head. You may instead have an ectopic pregnancy, a potentially life-threatening but relatively rare condition.