The National Institute of Child Health and Human Development explains if a woman misses more than two consecutive menstrual periods, she may be pregnant. It is important to talk to your health care practitioner about possible pregnancy if you miss menstrual periods to rule out other possible health complications. Women's College Hospital online states if you are pregnant, your nine-month pregnancy is divided into three trimesters of three months. During your pregnancy, your emotions will be more extreme than normal and you will experience physical signs of advancing pregnancy.
Week 1 to Week 6
After conception, the embryo is created. The fertilized egg attaches itself deep inside the uterus by the fourth week and tissue will be formed in the uterus. The mother may experience extreme fatigue and breast tenderness at this point. Cells begin to form and the embryo starts to grow and is almost an inch long by the sixth week. It develops ears and eyes, and blood starts getting pumped into the heart.
Week 7 to Week 12
According to the Mayo Clinic, the baby's head starts to develop by the seventh week of pregnancy and the brain, legs, nose and arms start developing as well. The baby's heartbeat begins in week 8 and the first ultrasound may be performed. By the end of the twelfth week of pregnancy, the fetus would have acquired fully-developed limbs and development of sexual organs would have begun.
Week 13 to Week 19
This stage would see the development of the digestive system of the fetus and movement of arms and legs would begin. An amniocentesis will be performed to rule out any birth defects. The baby gains weight and opens its eyes by week 18, and a wax-like substance forms a protective cover around the baby to make breathing easier in the nineteenth week.
Week 20 to Week 25
By week 22, the baby's development is almost complete and if the baby is a girl, her internal sex organs would have developed by week 20. The baby continues to grow and the spinal column, arteries and veins begin to form.
Week 26 to Week 31
The baby's respiratory system would be fully developed and all bodily functions and organs would have formed. By week 28, the baby becomes aware of sounds inside and outside the womb, and gradually the baby is able to smell, taste, see, hear and is able to blink.
Week 32 to Week 40
The baby continues to grow and eventually positions itself for birth. Week 40 marks the final week of pregnancy and labor may begin any time. The baby may be in the realm of 14 inches long from crown to bottom and weigh approximately 7 1/2 pounds. The Mayo Clinic states, "It's just as normal to deliver a baby a week or two late--or early--than it is to deliver on your due date."
