The second trimester of pregnancy is known as the most comfortable of the three phases.
The mother's belly isn't too big to be uncomfortable yet, and the pregnancy symptoms should have mainly subsided by now.
This stage is full of new developments.
The second trimester is when the belly really starts to show.
Changes in the mother's body - and the baby - will become more and more apparent.
Follow the weeks below to get a brief explanation of what is happening during the second phase of pregnancy, and watch for a follow-up pregnancy week by week guide that will outline the third trimester: Week 13 This week marks the beginning of the second trimester.
Most women claim this phase to be the most comfortable trimester of pregnancy.
Nausea is most likely subsiding, and energy is returning.
The baby is about 1 ounce now.
The eyes get closer together and the ears move into position.
The intestines are moving farther into the baby's body.
The baby's first stool is also developing, which is called 'meconium', and is like a black tar-like substance.
Week 14 This is when the belly really starts to 'show'.
There's no denying a pregnancy now! Hopefully, most of the pregnancy symptoms experienced during the first trimester will have subsided by now.
The placenta has now become the main source of nourishment for the baby.
Week 15 Your uterus can be felt about 3 or 4 inches below the navel.
At pre-natal visits, "fundal height" will be measured, which is the distance between the top of the uterus to the pubic bone.
The skin on the baby is almost transparent.
Blood vessels can actually be seen through the skin.
'Lanugo' covers the baby's body, which is very fine hair.
Week 16 Since your body is circulating an extra 40% to 50% more blood, you will notice more exaggerated veins, and even bleeding gums.
Nasal congestion may also continue to be a nuisance.
Fetal movement can now actually be felt through the belly, especially as the arms and legs grow.
Week 17 The pregnant mother-to-be will most likely have gained between 5 to 10 pounds at this point.
The uterus is about 1.
5 to 2 inches below the navel.
Fat begins to accumulate under the baby's skin.
Week 18 Back-aches, heartburn and dizziness may be experienced almost daily by now.
Another ultrasound may be scheduled right around now to verify fetal age.
If the baby is a boy, the prostate gland will start to develop .
Week 19 As the skin stretches, itchiness becomes a nuisance, especially around the belly, lower back and inner thighs.
Coco butter can greatly alleviate this discomfort.
The baby is covered with a coating called `vernix caseosa` - a white cheesy substance that protects the skin from the amniotic fluid.
Week 20 At this point, a dark line from the navel to the pubic area will probably be noticed.
This is called a "linea nigra", and disappears after delivery.
If the baby is a girl, her uterus is developed and her ovaries already have all the millions of eggs she will have throughout her life.
Week 21 A healthy weight gain at this stage is about 10 to 15 pounds.
Swollen feet and ankles will probably be a factor.
Drinking lots of water and keeping the feet elevated will help.
The baby`s rapid growth phase starts to decelerate now.
The legs are reaching their proper proportions, and the heart grows stronger.
Week 22 A pregnancy hormone called 'relaxin' will loosen the pelvic ligaments as well as the ligaments in the feet.
The bones will therefore spread slightly, and widen the foot.
Since the baby can actually hear the mother`s voice, speaking to the baby is an early bonding technique that the mother can engage in.
Week 23 Mood swings are quite common, especially as discomfort really sets in.
The baby actually has a chance of survival if it is born at this point.
Week 24 A glucose tolerance test will most likely be taken now as ordered by a health care practitioner.
This test will identify if gestational diabetes has developed.
The baby starts to really put on weight this week, as he or she will add another 6 ounces to the body weight.
The baby weighs about 1.
5 pounds, and is about 8.
5 inches long.
Week 25 Hemorrhoids are an uncomfortable symptom that more than half of all pregnant women experience.
These are caused by the growing uterus pressing down, in addition to the added blood flow.
A diet high in fiber should help this situation.
The baby`s air sacs will develop in the lungs, and the structures of the spine start to form.
Week 26 A common symptom occurring in the latter half of pregnancy is "Braxton Hicks".
These are painless contractions that feel like tightening and relaxing of the uterus.
This is the body's way of preparing for labor.
The baby's eyes begin opening, and brain wave activity for the visual and auditory systems begins.
Lungs continue to develop, and start to expand normally while breathing.
Week 27 Shortness of breath is common, and is due to the uterus growing so close to the lungs, therefore preventing the lungs from expanding fully to get in all the oxygen.
The baby weighs just over 2 pounds by now, and is about 9.
5 inches long from crown to rump.
This is the end of the second trimester, as week 28 welcomes the final phase of pregnancy.