Electrical activity can now be detected in the increasingly convoluted folds of gray matter, the part of your baby's brain that controls the higher functions, such as memory and consciousness, as well as muscle control and sensory perceptions, such as seeing and hearing.
The neurons of the cortex-the outer layer of gray matter-have started to develop into six distinct layers with separate functions, a process that will be completed in about five weeks, although further maturing will be needed. Your baby is born with almost a full complement of neurons, but there is further growth in early childhood.
For nerves to function effectively and signals to pass along them faster, they need insulating. In a process known as myelination, the nerves are insulated with myelin sheaths of fat. Although all of the components of the nervous system are present from an early stage of development, the peripheral sensory and motor nerves, spinal cord, and brain need the entire pregnancy to develop and function as a unit. The nerves of the brain and spinal cord carry the sensations of pain, temperature, and touch. However, the process of myelination is ongoing and will not be complete until the final few weeks of pregnancy, so your baby does not register or recognize pain, temperature, and touch at this stage.
A little way into your third trimester, the reality of childbirth may sink in. You may be experiencing some pregnancy discomforts, including Braxton Hicks' contractions (see Braxton Hicks' contractions), which give an indication of what is to come.
First of all, remember that the calmer and more relaxed you are, the easier your birth will be. Try to use a little positive visualization-your baby coming out easily in a "whoosh" of fluid, and focus on contractions being "positive pain" to bring your baby into the world. Remember that your baby will be fine, however long she takes to arrive, and that your pain and discomfort are all controllable. In other words, even if you decide on a natural birth now, you can get help and relief when you need it.
Try to relax and enjoy the last months of your pregnancy. Treat yourself to a massage, and keep yourself busy-perhaps undertaking a creative project for your new baby. Above all, don't worry. Think about childbirth as welcoming your baby into the world, and focus on this rather than any concerns.
Excerpted from Pregnancy Day by Day.
Copyright Ã‚Â©2009 Dorling Kindersley Limited.
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