You are now in the seventh month of your pregnancy, so two-third of the waiting period to meet your baby is over. With the beginning of the third trimester, you are probably starting to experience a new set of symptoms along with the existing ones. Your baby is going through the final developmental phase, with preterm babies born in the 28th week having a 90% survival rate without any major neurological or physical defects .
The brain structure continues to get more complex with characteristic indentions and grooves developing along its surface . The increasing number of brain tissues in the 28th week contributes in higher brain activity levels. The fetal brain waves are also starting to show distinguishable sleep cycles when your baby is asleep. The rapid eye movement (REM) phase can be detected as well, indicating that your baby might have started dreaming by this week . The sleep cycles continue to get more distinct as the third trimester advances .
Your baby is still practicing breathing in and out while blood vessels are developing throughout both the lungs. The chemical agent surfactant is produced to prevent the air sacs from sticking with each other once the lungs begin to absorb oxygen after your baby’s birth. The maturing bronchial tubes also start dividing into smaller branches this week .
The eyes that opened last week are quite sensitive to bright light at this stage. Your baby can now blink or even turn his head in the womb if you shine a bright light on your belly from the outside . This is also the week when the irises are filling with pigment; however, the eye color is not permanent and can change until he is 1 year old .
Your baby is now practicing various reflex actions including sucking harder than before, grasping anything that floats within range (usually the umbilical cord) and blinking his eyes . These will help him survive in the outside world once he comes out of the womb. Fetuses are often found sticking out their tongue after the 28th week. The exact reasons responsible for this action are still not known; but, it lets your baby taste the amniotic fluid as his taste buds are now matured enough .
The developing fat layers give the fetus an opaque and chubby appearance while fingernails begin to appear . Another noticeable change this week is the disappearance of the downy hair (lanugo) covering the fetus, as the job of regulating his body temperature is taken over by the fat underneath the skin layer .
Most babies move about 20 times within 30 minutes during their optimum activity period. Try to keep track of how much your baby is moving so you can detect any abnormality in his sleep and wake pattern as soon as possible. Consult your doctor to know the how much fetal movement is normal at this stage . In most cases, the babies settle into a head down position by this week, preparing for birth; but, they are likely to continue turning for a couple of more weeks .
The 28th week is an important phase of twin fetal viability with preterm multiples born this week having equal chances of surviving as single babies (about 90%). However, they are still at considerable risk of long term complications like cerebral palsy, vision problems and chronic breathing difficulties .
Your baby is almost as big as a kabocha squash , being about 15 inches (38 cm) long from head to toe with his weight ranging around 2.25 pounds (almost a kilogram) .
The top of your uterus is about 3.5 inches (8.9 cm) above your bellybutton this week  while the fundal height (the distance from the top of the uterus to the top of your pubic bone), should be somewhere between 10 inches and 11.5 inches (26 cm and 29 cm). The relaxin hormone loosening your joints and the growing belly shifting your center of gravity are causing your to drop things, bump into your furniture and trip over more often. Wearing flat comfortable shoes and moving slowly are recommended to avoid falling and harming your baby .
You have probably gained between 17 and 25 pounds in the earlier two trimesters , with the ideal weight gain level for the third trimester being around 5 pounds . You might notice a thick yellowish fluid (colostrum) leaking from the nipples as your body is still preparing for breastfeeding .
A 2D ultrasound performed this week will show your baby to be quite active, moving his arms and legs a lot, grabbing he umbilical cord and sucking on his thumb. You can also opt for a 3D ultrasound at this stage to get the first picture for your baby album.
Your doctor might order a blood test this week for checking your hemoglobin levels to detect anemia , while your blood pressure levels will be measured during each prenatal visit. You may also have to take a glucose challenge test (if you have not already) to check for gestational diabetes.
Rh-negative women are given a Rhogam shot (an Rh immunoglobulin or RhIg injection) to prevent Rhesus factor sensitization in the mother in case the baby’s blood possesses the antigen .
Published on August 1st 2014 by Pregmed Editorial Team.
Article was last reviewed on 13th August 2014.