You are almost halfway through the eighth month of your pregnancy with your baby going through the final stages of physical and mental development. Preterm babies born in the 33rd week of gestation have excellent chances of survival, about 98%, without any long term complication or developmental problems .
The fetal immune system is developing at a rapid pace with antibodies passing from your body to your baby so he can fight diseases and infections after birth .
The bone development continues into the 33rd week with the gradual hardening of the fetal skeleton . The bones in his skull are yet to fuse together, remaining in such a way until birth to make it easier for your baby’s head to pass through the birth canal. In fact, the skull bones do not fuse entirely until one reaches early adulthood, to allow proper brain expansion and tissue growth .
These last few weeks have been vital in the growth of the fetal respiratory system with the lungs now mature enough to allow your baby to breathe on his own if you were to give birth now. The chemical agent surfactant produced by your baby’s body helps to keep the airways (respiratory tracts) open, assisting in respiration . However, babies born during the 33rd week are kept in ventilation for a few weeks after birth so their lungs could pump oxygen and carbon dioxide at a steady pace.
By the 33rd week, there is almost 1 liter of amniotic fluid surrounding your baby, protecting him from any outside impact. The volume of amniotic fluid also signifies proper functioning of the fetal kidneys as your baby should be passing about 500 ml of urine in a day .
Other organs and systems like the brain and nervous systems have already completed their development in the womb  while the fetal liver is storing iron to help your baby grow after he enters this world .
Your baby’s skin appears smoother and more opaque with the growth of the fat layer underneath . He already looks like what he will on his birth day; however, he still has a considerable amount of weight to gain.
The baby is around 17.2 inches (43.68 cm) long by the 33rd week , weighing just over 4 pounds (1.8 kg), about the size of a pineapple .
Your baby does not have much space for those jerky movements you have been feeling in the early third trimester. The fetal activity levels now depend on your surroundings, external noises as well as when and what you eat . Your baby now shows newborn-like behaviour, opening his eyes when awake and even differentiating between night and day. The gradually thinning uterine walls allow more light to penetrate the womb, letting your baby know when it is daytime .
He should already be in a proper head down position for birth; although, do not worry if he is still in a breech position as there is still time for him to rotate in place. Your doctor will carefully monitor your baby’s position in these last few weeks to make sure he comes into the birth position before delivery .
By this week, you can feel the top of the uterus around 5 inches over your bellybutton . You have probably already gained about 22 pounds to 28 pounds by this point, with the ideal weight gain level from here on being 0.5 to 1 pound a week .
The hormone relaxin is produced in pregnancy by your body to loosen the pelvic joints and muscles to prepare your body for childbirth. But, the functioning of this hormone is not restricted within the pelvic area as it also relaxes the muscles and joints in other parts of the body, leading to pain and discomfort.
Women carrying multiples should gain 1.5 pounds per week throughout the third trimester . Their weight gain usually ranges around 30 pounds by the 33rd week. Maintaining a healthy diet with lots of iron, calcium and folic acid is essential to provide both babies with enough nutrients for proper mental and physical growth.
An ultrasound might be performed to assess the amniotic fluid levels or to check the position of your baby in the uterus in case your doctor suspects a breech baby .
Most women do not require any more medical exams and screening tests following the 28th week complete blood count performed to detect gestational diabetes (glucose tolerance ) and anemia . Those with low iron levels shown by their blood test are prescribed supplements and asked to come back for another blood count within a few more weeks.
Your doctor might order a screening test like amniocentesis during late pregnancy in case of a detected infection or complication like rupture or membranes 
Published on September 4th 2014 by Pregmed Editorial Team.
Article was last reviewed on 8th September 2014.