Second Trimester of Pregnancy
Written by : Dr.M.D.Mazumdar, MD
The second trimester is the period from the end of the 13th week of pregnancy to the end of the 27th week. It is a period of relative well-being for you - so it is also known as the 'honeymoon period'.
You will start to feel the first fetal movements at around 18-20 weeks of pregnancy. The fetal heart sound also becomes audible with a fetal doppler.
This is also the time when ultrasounds will indicate that the baby is anatomically normal. Tests like the Triple tests and Quad Screen will be done to check for chromosomal abnormalities.
By this time, the baby's gender will be clearly visible on ultrasound. By the end of this trimester, the baby has clearly defined limbs, the skin is covered with fine lanugo hair and the hand and toe prints appear. The baby can open his or her eyes and can respond to stimuli.
Some of the symptoms present in the first trimester will become more prominent now. You will also have some new symptoms.
Height of the uterus in pregnancy
Enlargement of the abdomen The height of the uterus increases to make it visible above the pelvic bones. If you lie down on your back, flex your knees and palpate your abdomen gently you will feel it as a firm, non-tender mass just above your pelvic bones.
The height of the uterus is given in the diagram. When the height of the uterus is just palpable, you are at 12 weeks.
When the upper edge of the uterus is at the upper edge of the umbilicus, you are 24 weeks. Lower edge of the umbilicus is 22 weeks.
Divide the area between the upper edge of the umbilicus and upper edge of the pubic bones into three equal parts and draw lines. This will give you the height of the uterus at 16 weeks and 20 weeks.
Again divide the area between your umbilicus and the sternum - your breast bone in the middle of your chest - into three parts and mark them with lines. These will give you the measurements for 28 weeks, 32 weeks and 36 weeks.
At term, that is, at 40 weeks, the uterus comes down below the level of 36 weeks but enlarges on the sides, making the flanks of the abdomen quite full. See the diagram for help.
You may develop an area of mild pigmentation with an ill-defined margin surrounding your areola. This is called the 'secondary areola'.
You may notice a number of small bumps around the edge your areola. These are called 'Montgomerys tubercles' and their secretions are responsible for keeping the nipples and areola supple and well-moisturized to function well during breastfeeding. They become more prominent as the pregnancy progresses.
Thin bluish veins may become more prominent on the breast.
Read more about sore breasts in pregnancy here ...
Stria gravidarum (Stretch Marks): Stria gravidarum or stretch marks first start to appear in the later part of the 2nd trimester or the early part of the 3rd trimester.
As the uterus increases in size, it presses against the skin of the abdomen. The skin, being unable to take the weight of the heavy uterus undergoes minor tears and injuries in its lower layers. These show up as the scars that we call 'stria gravidarum' or stretch marks.
In the early stage, the striae are thin, purplish or pinkish marks but as they get older and heal, they become a faint, silvery colour. As a result in later pregnancy, a mixture of fresh purplish striae and healed silvery striae may be seen.
In women with strong abdominal muscles, e.g. women who work out regularly, the muscles rather than the skin, take the weight of the uterus and they have less or no striae.
Read more about stretch marks in pregnancy here ...
Foetal Movements The first foetal movements felt by the mother is called 'quickening'. If this is your first pregnancy, you will feel the first foetal movements at around the 18th - 20th weeks of pregnancy.
Women in their second or third pregnancies, being more experienced, can feel it earlier, at about the 16th - 18th weeks.
Most women describe the first foetal movements as a faint fluttery feeling deep in their abdomen that occurs quite suddenly and vanishes just as suddenly.
Others describe it as a quick throbbing sensation that lasts for a few seconds and then disappears.
Sometimes the movements can be so soft and start so gradually that you may not even be aware of when it first started.
Always inform your doctor about the first foetal movements as it makes it easier for her to date the pregnancy and estimate the expected date of delivery, more so if you are not sure of the date of your last menstrual period.
Linea Nigra: This is a thin, dark line extending from the umbilicus to just above the pelvic bones in the middle. It is darker in dark-skinned women. It has no particular function or significance.
On examination, your doctor will measure the height of the uterus and check that it corresponds to your gestational age (GA), that is, the height of the uterus according to the LMP. In women who are very tall, the height of the uterus may appear to be less than the GA, while in women who are very short, the height of the uterus may be more than the GA.
The foetal heart sound (FHS) becomes audible with a stethoscope at about the 16th week.How early the sound can be picked up depends on the baby's position, as well as the mother's weight. It has often been described as resembling the 'faint and distant ticking of a watch placed under a pillow'.
The FHS varies within a range of 140 - 160 per minute at 20 weeks and comes down to 120 - 140 per minute at term. If the rate falls below 100 per minute or rises above 160 per minute at term, it signifies danger to the foetus and a caesarian section becomes necessary as early as possible.