What are the differences between the second and third trimesters of pregnancy?

The Second and Third trimesters of pregnancy are the stages when the fetus grows the most during a pregnancy.

Second Trimester

The time between week 13 and week 25 is termed as the Second Trimester. It is during this period that the rib cage starts to develop along with other skeletal bones, red blood cells begin to form and also urine is formed. The nerves, muscles and vital organs are functioning. Fetal activity increases and the mother can feel the movements also known as ‘quickening’ around the 20th and 21st week. An ultrasound scan can show the gender of the fetus and the swallowing and sucking motions made by the baby’s mouth or throat may also be visible. The fetus grows almost three times its length during these 13 weeks. The ears have developed and the fetus starts to react to noises. Fat stores start forming under the skin to provide energy and make sure that the baby is warm after birth. The fingerprints and footprints too begin to form around the end of this trimester. The fingernails also start growing and sometimes they may need to be trimmed immediately after birth. Morning sickness begins to reduce and eventually fades away and most women start gaining weight and feel energized.  

Third Trimester

The Third Trimester begins at week 26 until the birth. The fetus gains approximately 28 grams every day making it the period of the most rapid growth. The lungs start developing at this stage making sure that the baby is strong enough to breathe on its own after birth. The sensory organs have developed, the eyes open and can detect light. The fetus can also hear and remember voices and music heard during this time even after birth. The belly of the woman transforms in shape as the fetus prepares for birth and drops downwards. The womans navel will change shape and ‘pop’ out, becoming convex due to the growing abdomen. The fetus movements are more frequent and stronger due to better brain, muscle and eye functions. This is the period of increasing discomfort with symptoms including backaches and a weak bladder. The ‘rolling’ of the fetus can cause discomfort and pain when it is near the ribs or spine. A woman may also have trouble breathing due to the expanding uterus putting pressure on the diaphragm. If the baby is born pre-term or prematurely during this period, the chances of survival are very high due to available modern medical facilities.

Submitted by P T on January 18, 2010 at 10:56

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