Our Pregnancy Calendar will help you find out how your baby grows and changes from a small group of cells to a fully developed baby ready to begin life.
|Select Your Week|
|Track your progress week by week|
31 Weeks Pregnant
During late pregnancy the back pains are almost inevitable. The reason is that back joints and muscles are resting and relaxing now in order to prepare for birth process. There is a possibility of venous distensibility or vein expansion on legs. The heartburns will bother you more and more. Your body produces a hormone called relaxin, which relaxes the pelvic bones and muscles, preparing them for birth. Because of it you can walk like a duck. Some women do not experience any discomfort with pains in the pelvis, waist, tailbone and walking. But it does not mean that their bodies are not preparing for birth. It all depends on various factors like heredity and level of physical readiness, etc.
A woman by this time gains around 19 lbs of extra weight. The increase is formed by the baby’s weight, the placenta, the amniotic fluid, the size of the uterus, total amount of blood in vessels and as well as fatty tissue, proteins and high concentration of water in the body.
If your baby was born this week, his chances to survive would be much higher thanks to high level of matureness of the pulmonary tissue. Although at earlier stages bronchial tubes and air sacs were generated, the baby still could not breathe. But now a layer of epithelial cells that release surfactant has formed in the alveolar or air sacs. These surface-active substances smooth the lungs out allowing the baby to draw the air in and breathe independently.
About 500 ml of blood passes through the circulation system of the uterus, which is in a very close contact with the capillary system of the placenta that is charge of blood circulation inside the fetus. Your blood never blends with the baby’s blood despite the fact that they are divided by a very thin partition, the placental barrier through which the exchange of water, nutrients, and waste is carried out with a speed of 10 ml a second. Besides that the baby swallows the amniotic fluid also that is later released out with urine. Because of increase in the baby’s fatty tissue his skin does not seem red as earlier but looks more like a pink.
Baby length and weight
Length from crown to sacrum - approximately 15-16 inches.
Weight - approximately 3.3 lbs.