Skip to content

The Second Trimester of Pregnancy

The second trimester, which encompasses the three months between weeks 13 and 26, is often the most enjoyable part of pregnancy. The feelings of nausea and fatigue so common during the first trimester are usually gone, and you feel more energetic and comfortable. The second trimester is a very exciting time because you can feel the baby moving within you and you’re finally starting to show. During the second trimester, blood tests, prenatal tests, and ultrasound (sonogram) can confirm that the baby is healthy and growing normally. And many women find they can finally grasp the concept that they’ll soon be having a baby. The second trimester is often the time you start sharing the exciting news with family, friends, and co-workers.

What Changes Occur in the Women’s Body in the Second Trimester?

By 12 weeks, your uterus begins to rise out of your pelvis. Your practitioner can feel the top of the uterus through your abdominal wall. By 20 weeks, the top of your uterus reaches the level of your navel. Then each week, your uterus grows by about one centimeter (1/2 inch). Some women look pregnant at 12 weeks; others aren’t obvious until 28 weeks.

You may experience some, none, or all the symptoms in this Trimester.

  • Forgetfulness and Clumsiness
  • Gas
  • Hair and Nail Growth
  • Heartburn
  • Lower abdominal Pain
  • Nasal Congestion
  • Nosebleeds and bleeding gums
  • Skin changes
  • Dizziness or lightheadedness due to Lower Blood Pressure
  • Feel the Movement of Baby

What Should You Do to Stay Healthy in the Second Trimester?

Every pregnant woman should aware, what to do and what not to do to stay healthy during pregnancy. These suggestions will help to take care of yourself and your developing baby.

What to Do:

  • Exercise Regularly
  • Work out your pelvic floor by doing Kegel Exercises
  • Take Parental Vitamins Regularly
  • Eat a Healthy diet Especially fruits, vegetables, and fiber
  • Drink water at least 3-4 liters daily
  • Eat Enough Calories

What not to DO:

  • Strenuous Exercise
  • Alcohol
  • More use of Caffeine
  • Smoking
  • Illegal Drugs
  • Raw fish or Smoked Seafood
  • Raw Sprouts
  • Unpasteurized milk or other dairy products
  • Deli meats or hot dogs

When You Should Consult the Doctor?

Certain problems that can develop during the second trimester and symptoms that you should discuss with your practitioner.

1. Bleeding

Some women experience bleeding in the second trimester. Possible causes include a low-lying placenta (placenta previa), premature labor, cervical incompetence, or placental abruption.  If you do experience bleeding, it doesn’t necessarily mean you will have a miscarriage, but you should call your doctor. Most often he recommends you have an ultrasound exam and be monitored to make sure that you’re not contracting. Bleeding may increase the risk for premature delivery, so your doctor may recommend that your pregnancy come under extra-close surveillance.

2. Fetal Abnormality

Although the vast majority of pregnancies proceed normally, about 2 to 3 percent of infants are born with some abnormality. Most of these abnormalities are minor, although some do lead to significant problems for the newborn. Some are due to chromosomal problems, and others stem from the abnormal development of organs and structures. For example, some newborns may have heart defects or abnormalities of the kidneys, bladder, or gastrointestinal tract. Many of these problems, though not all of them, can be diagnosed on a prenatal ultrasound exam.

3. Incompetent Cervix

During the second trimester, usually between 16 and 24 weeks, some women develop a problem known as an incompetent cervix or cervical insufficiency. The cervix opens up and dilates, even though the woman feels no contractions. This condition may lead to miscarriage. Indeed, an incompetent cervix is most often diagnosed after the miscarriage occurs and, in most cases, couldn’t have been predicted.

Knowing when to Seek Help

The following is a list of second-trimester symptoms that require some attention. If you experience any of them, call your practitioner:

  • Bleeding
  • An unusual sense of pressure or Heaviness
  • Regular Contraction or Strong Cramping
  • A lack of normal fetal movement
  • High Fever
  • Severe Abdominal Pain

Changes in the Second Trimester

The fourth month marks the beginning of the second trimester. The uterus has expanded to reach the top of the pelvis and can be felt above the pubic bone. This means the pregnancy will soon start to show. We will now discuss the changes on weekly basis:

Week 13

Some pregnancy symptoms, such as morning sickness, are improving but others, such as constipation and indigestion, may take their place. In the fetus, sweat glands are appearing and hair can be seen on the scalp. A clearly defined neck has formed, and the chin is more upright. The head seems large for the body, representing half the crown-rump length. The arms have grown in proportion to the body, but the legs still look too small. The muscular and nervous systems are developed enough to allow uncoordinated limb movements. The spinal cord extends the full length of the vertebral canal, and nerve cells in the brain and peripheral nervous system are increasing and migrating to their proper places. Also, nerve fibers are slowly being insulated with a fatty myelin sheath.

Week 14

Changes in maternal blood flow and blood volume often give a mother-to-be a healthy color, which is referred to as the pregnancy “glow”. Combined with an expanding abdomen, this glow is an
external clue to her pregnant state. The fetus is now growing rapidly, and over the next three weeks, it will double in size, as fat, in addition to glucose, is now used as an energy source. As a result, the fetal body is now longer than the head. The placenta still acts as a kidney to control the fluid balance, but the fetus’s urinary system is now sufficiently developed to produce tiny amounts of very dilute urine. The bladder fills and contracts every 30 minutes, but it can only hold a small amount of fluid – less than a teaspoonful. Miniature toenails are now growing in the nail beds.

Week 15

As fetal growth accelerates, amino acids are extracted from the mother’s blood to build muscles and organs in the fetus. The fetus drinks amniotic fluid, which acquires flavors from the mother’s diet. The lungs are expanding and producing small amounts of mucus. The external sex organs are now visible, and it may be possible to identify gender from an ultrasound scan. During this month, hundreds of thousands of eggs are forming within the ovaries of a female fetus. At the same time, the ovaries move down from the abdomen into the pelvis. The umbilical cord is thickening and lengthening as it carries more and more oxygenated blood, rich with nutrients, from the placenta to the fetus and returns deoxygenated blood and wastes to the mother’s body.

Week 16

The fetus’s face looks obviously human, with eyes in the correct forward-looking position and ears moving up towards their final position. The thyroid gland is descending from the base of the
tongue into the neck. The fetus is now almost equal in size to the placenta, and the second wave of placental growth now anchors it more firmly to the uterus as blood flow to the fetus increases. Mothers-to-be are offered a number of screening tests, including amniocentesis, in which a sample of amniotic fluid is collected to analyze fetal cells. This procedure can be performed from 15
weeks, but is usually undertaken between 15 and 16 weeks. It is normally only offered to mothers with a higher than normal risk of a baby with chromosomal abnormalities such as Down’s syndrome.

Week 17

For the first time, the fetus has now grown larger than the placenta that anchors it to the womb lining. Its proportions are changing, although the head, hands, and feet still seem too large for the body. The legs and trunk continue to grow at different rates, and body proportions will slowly continue to become normal. The nervous system is developing apace, and a fatty myelin sheath begins to form around some nerves. This process, which is known as myelination, continues through the rest of fetal life and early childhood. Myelination helps to speed up electrical communication between the body and brain. The fetus can now move its arms and legs quite vigorously, and as myelination continues the limb movements gradually become better coordinated.

Week 18

Some pregnant women notice skin pigment changes on their face and abdomen. These changes are caused by the hormones produced during pregnancy and will fade after delivery. The mother’s breasts are becoming larger, and her nipples tend to become darker and more pronounced as the pregnancy progresses. Small lubricating glands, called Montgomery’s tubercles, may appear around the nipples, and large veins may be visible in the breasts. The fetus’s facial features are well-formed, and it can produce facial expressions, such as smiling, grimacing, and frowning. It swallows amniotic fluid regularly and will often hiccup strongly enough for the mother to feel. The fetal skin is transparent and paper-thin, and fingerprints are forming ridges on the tips of the fingers.


The areola develops glands called Montgomery’s tubercles, which secrete a scented oil that attracts the baby to the nipple.

Week 19

By the end of the 19th week, the full complement of milk teeth buds has formed – ten in the upper jaw and ten in the lower jaw. These tiny teeth buds lie dormant beneath the gums until some time after birth. The fetus’s eyebrows and scalp hair are becoming visible, but the eyelids are still firmly fused together to protect the delicate developing eye beneath. The fetus continues growing rapidly, and the top of the uterus grows upwards by around 1cm (3/8in) per week. The top of the uterus is now almost level with the mother’s belly button (navel or umbilicus). The cartilage that forms the blueprint for the fetal skeleton is starting to harden in some places to form areas of bone. This process, known as ossification, continues after birth to allow childhood growth.


The pregnancy is nearing the halfway stage, and the top of the uterus (fundus) grows upwards at an astonishing rate.

Week 20

Between 18 and 20 weeks, a mid-pregnancy scan is carried out in order to check that the fetus’s limbs and organs are developing correctly. The external genitals are now visible, and the sex of the
fetus has become more obvious on ultrasound scans. In a female fetus, the ovaries have descended from the abdomen into the pelvis. In a male fetus, the testes are also descending, but they have not yet passed out of the body into the scrotum. The ability of the fetus to interact with its environment is increasing due to the development of the nervous system. Amazingly, the fetus can already detect a number of sounds and tastes, and nerve pathways that carry information about pain, temperature, and touch are starting to develop. The first tentative sparks of awareness are in place.

Week 21

The fetus is growing steadily, and fat is laid down beneath the skin. Although the skin is still wrinkled and pink, it has developed two layers and is less transparent. Palm creases and fingerprints are apparent. Small amounts of meconium – a solid, green-black substance comprising gut lining cells and waste from swallowed amniotic fluid – pass through the gut. The anal sphincter starts to function at around 21 weeks.

Week 22

The bones within the fetus’s inner ear are beginning to harden, and the coiled cochlear membrane is sufficiently developed to process low-frequency sounds. Over the coming weeks, the fetus starts to be aware of higher sound frequencies, too. The nervous system is now developed enough for the fetus to start recognizing the sounds inside the uterus, such as the mother’s breathing, heartbeat, stomach and intestinal rumbles, and her voice. It may be noticeable that the fetus becomes increasingly responsive to sounds, and it will develop a startle reaction to loud noises. As the nervous system develops, the fetus becomes able to make much more sophisticated movements, such as kicking and turning somersaults, and the mother will be aware of this increased internal activity.

Week 23

The fetal skin cells now start to accumulate a tough, protective protein called keratin, the thickest layer of which is on the palms and soles of the feet. The skin is very wrinkled and is covered in
greasy vernix and fine lanugo hair, which protect the fetus in its aquatic environment and may have an insulating effect. The nails start to appear at the base of the nail beds, and eyelids and
eyebrows are developing. Small blood vessels appear in the lungs. The barrier between these capillaries and the future air sacs is thinning to allow the exchange of gases when the baby is born. Specialized lung lining cells (pneumocytes) are appearing. These will produce a substance called surfactant, which reduces surface tension so the small air sacs can expand more easily after birth.

Week 24

Parts of the fetus’s brain involved in vision and hearing are becoming more active. Memory is developing, and brain-wave activity is now similar to that of a newborn infant. The mouth and
lips show increased sensitivity, and the fetus hiccups and yawns more often than before. Growth of the body and legs has caught up with the head. Teeth buds for the adult set of teeth are appearing in the gums, and the nostrils are opening.

Week 25

The fetus is now growing rapidly as it accumulates muscle and fat. The mother’s uterus enlarges correspondingly, both upwards and outwards. This changes her center of gravity, and she must adapt her posture in order to maintain balance. These changes can lead to problems such as backache. As the uterus grows, it also presses against the stomach and diaphragm, which can reduce the ability to breathe in deeply and may increase symptoms of acid reflux and indigestion. The fetus’s brain is becoming increasingly complex. Nerve cells (neurons) are making new connections and laying down many nerve pathways. Some pathways receive sensory information from the body, while others send instructions to co-ordinate voluntary and involuntary movements.

Week 26

The framework for the grey matter (cortex) of the fetus’s brain is now in place. This is the location of nerve activity associated with consciousness, personality, and the ability to think. Around this
time, fetal hand coordination dramatically improves. The fetus can close its hands to make a fist and may spend a lot of time sucking its thumb. The brain surface is still looking smooth but as the cortex continues to mature, it will start to fold and form characteristic wrinkles. The testes in a male fetus now descend from the pelvis into the scrotum. The eyelids, which have remained fused since they formed during the ninth week of development, also start to open. The fetus will blink regularly and may turn towards very strong light that filters through the mother’s abdomen.

Leave a Reply

Your email address will not be published. Required fields are marked *