Week 28: Viability! If you had to give birth as early as this week, it is comforting to know that your baby has a 96% chance of defect-free survival. Up until this point, if your baby were to be born early, long-term problems could range in severity from anything like seizure disorder and palsy to blindness or deafness.
The baby has eyelashes and will turn its head in response to light. The baby will go through another growth spurt and begin to put on more fat. About 40% of babies will be head down this week. If you have had one or more children already, your baby may not have turned yet.
Week 29: The baby's nutritional needs will begin to peak starting this week. Omega oil for brain development, calcium for bones and iron are all critical. This week, a pregnant woman's iron level reaches its lowest point. The average baby is about 2 1/2 lbs and 15 inches long.
Week 30: The baby is about 3lbs. It can produce tears. Between now and week 40, the baby will put on weight at a rapid rate. In a very short amount of time, even the most careful of pregnant women will suddenly begin to look and feel huge.
Week 31: The baby is about 16 inches long and has put on more fat.
Week 32: The baby's toenails have finished forming. It weighs about 4lbs and is about 17 inches long.
Week 33: The baby's bones, with the exception of the skull, are hardening. The baby has also gained more weight.
Week 34: On average, the baby is about 4 3/4 pounds and about 18 inches long. The fat layers are filling out and the lungs are well developed by now. About 99% of babies born at this age survive and most have no major long-term problems related to prematurity.
Week 35: The average baby weighs about 5lbs. The kidneys are fully developed and the liver can process waste products. It is a myth that you will feel the baby move less by this point. Movement rate is the same. It is the strength and type of movement that changes. For example, you are (significantly) less likely to feel fluttery kicks, and more likely to feel hard kicks into the ribs or head-butts to the top of the cervix.
Week 36: The vernix and fine hair that covered the baby earlier in pregnancy is being lost. Some vernix will remain to assist in passage through the birth canal. The average baby is about 6lbs and 19 inches long. Between now and the end of the pregnancy, the baby could put on as much as 1/2 to 1lb per week. In most cases, the baby has "dropped," that is to say the head is fully engaged on top of the birth canal. For some women, this is a relief since it may make breathing easier if the baby's feet have been digging into the ribs. If you were already carrying relatively low however, then this may mark a time of discomfort.
Week 37: The baby is no longer premature. If you deliver this week, it is considered a normal birth. Depending on the parents, the baby may have a full head of hair. However, the hair may not be the same colour as either parent and it may be shed after birth. If the baby is not head down at this point, you could be at risk for a breach birth. However, there is no reason to panic. Not only are there manual methods of turn the baby into a head down position, but some babies do not turn until immediately before labour. This may be particularly true if you have had a lot of children and your uterus is "roomy."
Week 38 - 40: In terms of development, not much changes with the baby during these weeks. It grows longer, stronger and puts on more weight.
There is a lot more that can be said about pregnancy, especially in terms of the pregnant woman's experience. In terms of the birthing process itself (which I do not plan to cover) there is a high degree of variation from woman to woman. Statistically speaking, sisters are more likely to have similar pregnancies than mothers and daughters. However, it is most likely that your experience will be unique to you with only some similarities to family members.