You're in your last trimester—congratulations! While it might seem like your belly is ready to burst, your baby-to-be still has plenty of growing ahead of her. In fact, the big story this trimester will be your baby's weight. At about the 30th week, she'll start gaining 1/2 a pound each week. Just think: In the first trimester she was gaining a fraction of an ounce each week, and now she's gaining 1 pound every two weeks!
All that baby weight is for more than filling out her chubby cheeks. Now that all of her major body systems are in place and functioning, she needs padding to protect and insulate her organs. Her built-up fat tissue will also help her regulate her body temperature after birth and provide the energy she needs.
Because your baby is adding fat and growing bigger, you might find her movements become less frequent—it's getting harder for her to maneuver! She was once able to freely kick her legs and move her arms above her head. Now her home is becoming more cramped. You will probably feel more persistent pushes rather than in utero dance recitals. That's normal. Her lack of space is one cue it's getting closer to delivery day. Your health care provider might evaluate your baby's position during prenatal visits to see if she's begun pointing her head down in preparation for birth. To get a closer look at your baby's position, your provider might even request an ultrasound. If you do receive an ultrasound in the third trimester, notice that your baby's entire length no longer fits in the view screen.
Even more exciting is that your baby can open and close her eyes at will now, and she'll suck her thumb if she's so inclined. Plus, her brain is developing even more rapidly right now. An ultrasound of your baby at 28 weeks shows a head that is large in proportion to her body; at birth, a human baby's brain accounts for a whopping 12 percent of his body weight. Your baby already has the 100 billion or so brain cells she'll have at birth. However, she still has to build connections between them to form the neurological network that will give her control over everything from her footsteps to her speech. The placental blood flow is increasing dramatically to support your baby's rapid growth during the third trimester, and the placenta itself is growing. For example, the placenta weighed only about 6 ounces during your 20th week of pregnancy, but by now it's probably close to 15 ounces.
Right Occiput Anterior (ROA): In this common fetal body placement before birth, the baby's head faces to the mother's left thigh (to the health care provider's right if she's facing the birthing baby), and the baby's face is more toward the mother's buttocks. This position is one of the easier positions for the baby to be in to navigate the birth canal.
Left Occiput Anterior (LOA): As with ROA, this common fetal body position makes it easier for the baby to go through the birth canal versus other positions. With LOA, the baby's head is turned diagonally toward the mother's right thigh and buttocks; from the health care provider's perspective, then, the baby's head is facing left and downward.
Images courtesy of the American Institute of Ultrasound in Medicine (AIUM.org).