Pregnancy trimesters – course, child development, tests

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The duration of pregnancy can be divided into 3 trimesters, each lasting 3 months. There are specific moments in your baby’s development at each stage of the trimester. The first internal organs, hands, legs appear, it is possible to determine the sex of the child. What does the baby’s development look like in the mother’s belly? What important events are happening in each trimester of pregnancy?

Trimesters of pregnancy – duration

Doctors currently divide pregnancy into three phases called trimesters. Each trimester is made up of a certain number of weeks:

1. first trimester: 1-13 weeks,
2. second trimester: 14-27 weeks,
3. third trimester: week 28-40.

The first trimester is the most delicate and important period of pregnancy. During this trimester, all the most important organs and systems in the baby’s body are being formed. Most birth defects and miscarriages occur during the first trimester of pregnancy.

In the second trimester (12-24 weeks), the fetus has already developed all its organs and systems, now it is growing and gaining weight. The third trimester is actually waiting and preparing for the birth.

Also read: Scientists: COVID-19 vaccines do not cause infertility or miscarriage

First trimester of pregnancy – baby development

The first trimester of pregnancy is a very important period for both the pregnant woman and the developing fetus. It is during this period that all systems and organs of a child develop. Read how your baby develops by week in the first trimester of pregnancy:

4th – 5th week of pregnancy:

1. all major systems and organs begin to form,
2. the embryo looks like a tadpole,
3. a neural tube (which becomes the brain and spinal cord) begins to form,
4. the seeds of the eyes and ears develop,
5. small buds of limbs appear (which will develop into the arms and legs).

After 8 weeks of pregnancy:

1. all major organs and external body structures began to form,
2. the baby’s heart beats in a regular rhythm,
3. arms and legs lengthen, fingers and toes begin to form,
4. genitalia begin to form,
5. eyes moved to the front of the face and eyelids formed,
6. the umbilical cord is clearly visible.

After 12 weeks of pregnancy:

1. nerves and muscles start working together. Your child can make a fist
2. external genitalia are visible,
3. the lids close to protect the developing eyes. They won’t reopen until week 28.

Read: Umbilical cord stump – how is it formed?

The first trimester of pregnancy – changes in the female body

The time of pregnancy for a woman’s body is a time of huge changes. Every woman experiences a completely different pregnancy, and the symptoms characteristic for each trimester of pregnancy may be intensified for each woman to a different degree. Some symptoms of pregnancy last for weeks or months, while others only last for a short time. Some women experience many symptoms while other women experience few or no symptoms. The following is a list of changes and symptoms that may occur during the first trimester of pregnancy:

1. the mammary glands enlarge, making the breasts swollen and tender. This is due to the increased amount of the hormones estrogen and progesterone. Please wear a supportive bra
2. areolae around the nipple (colored areas around the nipple) enlarge, darken, and may become covered with small white lumps called Montgomery’s nodules (enlarged sweat glands)
3. the veins become more visible on the surface of the breast
4. the growing uterus compresses the woman’s bladder, causing the need to urinate more often,
5. Due in part to the surge in hormone levels, a pregnant woman may experience PMS-like mood swings (a condition some women experience, characterized by mood swings, irritability and other physical symptoms that begin shortly before each period).
6. high levels of pregnancy-supporting hormones can cause ‘morning sickness’, which is nausea, and sometimes vomiting. However, morning sickness does not necessarily appear in the morning and rarely interferes with the proper nutrition of the mother and fetus.
7. constipation may occur when the growing uterus presses against the anus and intestines
8. The muscle contractions in the intestines that help move food through the digestive tract are slowed down due to the high levels of progesterone. This, in turn, can cause heartburn, indigestion, constipation and gas.
9. clothes may start to tighten around the breasts and waistline as the abdomen begins to enlarge to accommodate the growing fetus.
10. a woman may feel tired due to the physical and emotional symptoms of pregnancy.
11. the volume of the heart increases by about 40 to 50 percent from the beginning to the end of pregnancy, causing an increased cardiac output. Increased cardiac output can cause an increased heart rate during pregnancy. Increasing blood volume is needed for additional blood flow to the uterus.

First trimester of pregnancy – tests

Examination during pregnancy is extremely important, as the health (and sometimes life) of the future mother and baby depends on them. The first test a woman who believes she is pregnant will do a home pregnancy test. This test is available at every pharmacy and drugstore. A pregnancy test detects the presence of hCG in the urine, or human chorionic gonadotropin, a hormone produced by embryonic tissues.

The pregnancy test is best done in the morning when you pass your first morning urine. The test is very easy to use, just put a few drops of urine on the tester and wait for a while. If there are two lines on the test, it means you are pregnant, if you see one line, it means you are not pregnant.

However, it should be remembered that although the pregnancy test is positive, an hCG blood test should be performed to confirm pregnancy. This test not only confirms or excludes pregnancy, but also indicates, in the case of pregnancy, its amount in the blood – thanks to this it is known whether the fetus is developing properly.

Blood hCG should be confirmed 48 hours apart. If the amount of hCG in your blood doubles in the second test, your pregnancy is developing normally. You can perform this examination yourself, you do not need to have a referral (then it is payable) and go to the gynecologist with the result. You can also do them only after the visit, then you will receive a referral.

So, if your pregnancy test showed a positive result and you have had a blood test for hCG that also indicates you are pregnant, it’s time to see your gynecologist. Then, he will confirm the pregnancy on ultrasound. It is best to go to the doctor about 8 weeks after the expected period – which did not appear due to pregnancy, but not later than before the 10th week of pregnancy.

The ultrasound will check the pregnancy, determine whether the pregnancy is single or multiple, and whether the developing baby has settled well in the uterus and is developing normally. The ultrasound examination in the first trimester of pregnancy is performed vaginally before the 10th week of pregnancy. During the first trimester and pregnancy, an ultrasound scan is essential!

At the first visit, the gynecologist will also refer you to a series of tests that should be performed before the 10th week of pregnancy. It is i.a. examination / a:

1. determining the blood group and the Rh factor,
2. determining the level of sugar in the blood,
3. blood count,
4. cytology (if it has not been done within the last 6 months),
5. examination of the mammary glands,
6. vaginal pH test,
7. general urine test,
8. syphilis test (VDRL),
9. HIV testing
10. HCV screening,
11. testing of immune antibodies,
12. testing of antibodies against rubella and toxoplasmosis (IgM and IgG),
13. Wassermann’s test (WR).

During the first trimester of pregnancy, before the age of 10 weeks, some gynecologists recommend TSH levels and HBs antigen testing for pregnant women.

In the first trimester of pregnancy, between 11th and 14th (13 + 6) weeks, the following should also be done:

1. urine test,
2. blood pressure measurement,
3. body weight measurement,
4. gynecological examination.

Ultrasound examination of the developing child. Performing such an ultrasound examination during this period is to assess the structure of the fetus, its dimensions, internal organs, as well as to estimate the risk of genetic defects.

Also check: Are you planning a pregnancy? Start with research – take care of your and your baby’s health

Second trimester of pregnancy – baby development

The second trimester of pregnancy is a turning point for the pregnant woman and the baby. A woman usually begins to feel better and begins to show pregnancy more often. All organs and systems have developed in the child, now it only grows and increases its weight. During the second trimester, baby’s development is as follows:

at the age of 16 weeks:

1. muscle tissue and bones continue to form to form a more complete skeleton
2. skin begins to form,
3. meconium develops in the baby’s digestive tract,
4. your baby is sucking with his mouth (suckling reflex).

at the age of 20 weeks:

1. your baby is more active. You can feel the baby’s light movements,
2. your baby is covered with thin, fluffy hair called lanugo and a waxy coating called vernix. This protects the skin that forms underneath,
3. eyebrows, eyelashes, nails and toenails were formed. Your child may even scratch
4. your baby hears and swallows.

at the age of 24 weeks:

1. the bone marrow begins to produce blood cells
2. taste buds form on the child’s tongue,
3. real hair starts to grow on the baby’s head,
4. hand reflex develops,
5. Your baby sleeps and wakes up regularly.

If your baby is a boy, his testicles begin to move from the abdomen to the scrotum. If your baby is a girl, her uterus and ovaries are in place and the eggs have formed in the ovaries.

Second trimester of pregnancy – changes in the female body

The second trimester of pregnancy is the most physically pleasant for most women. Morning sickness usually subsides, and extreme tiredness and breast tenderness are forgotten. These changes can be attributed to a decrease in human chorionic gonadotropin (hCG) levels and an adjustment of estrogen and progesterone levels.

The following is a list of changes and symptoms that may occur during the second trimester of pregnancy:

1. increase in appetite,
2. the woman may be able to feel the fetus move for the first time (around week 20 of pregnancy)
3. the uterus has grown to the level of the navel, thanks to which the pregnancy is visible,
4. the growing skin on your stomach may itch and the sides of your body may feel pain as you stretch your uterus. The lower abdomen may hurt as the ligaments stretch to support the uterus.
5. the need to urinate frequently may decrease,
6. epistaxis may occur. This is due to an increase in hormones (estrogen and progesterone) that affect the nasal mucosa,
7. female gums become spongy and may bleed easily. This is due to an increase in hormones (estrogen and progesterone) that affect the oral mucosa,
8. varicose veins and hemorrhoids may appear,
9. increasing weight gain can cause back pain,
10. skin pigmentation on the face or abdomen may change due to pregnancy hormones,
11. heartburn, indigestion and constipation may still persist.

Read: The female reproductive age has increased by two years. This could have health implications

Second trimester of pregnancy – tests

During the second trimester of pregnancy, the following tests should be performed:

1. ultrasound examination half, (between 18 and 22 weeks of pregnancy) is a detailed assessment of the fetal organs in terms of the presence of congenital abnormalities (assessment of the anatomy of the fetus);
2. glucose load test (between 24 and 28 weeks of pregnancy)
3. general urine test,
4. blood count,
5. toxoplasmosis (IgM) test, if the woman was negative in the first trimester.

Third trimester of pregnancy – child development

The third trimester of pregnancy is the period when the expectant mother prepares for childbirth. The baby continues to grow in weight and size, and body systems complete puberty. Pregnant may feel more uncomfortable now as she continues to gain weight and begins to have predictive contractions (called Braxton-Hicks contractions).

During the third trimester of pregnancy, the baby continues to grow in size and weight. The lungs continue to mature and the baby begins to face downward. Your baby’s development in the third trimester includes:

1. the child sees and hears,
2. the brain continues to develop,
3. kidneys and lungs continue to mature
4. the skull bones remain soft to facilitate passage through the birth canal,
5. in many children, the irises of the eyes are light blue. Persistent eye color will not appear until a few days or weeks after birth.
6. the child can suck their thumb and even cry,
7. after 38-40 weeks the lanugo disappeared almost completely,
8. from 38 to 40 weeks the lungs will be fully mature
9. the child is covered with vernix caseosa (or simply vernix), a cream, protective coating on the skin,
10. fatty tissue increases. Your baby is getting bigger and has less and less space to move around,
11. baby’s head goes down during the last few weeks of pregnancy.

See: Well-being before childbirth – harbingers of the upcoming delivery

Third trimester of pregnancy – changes in the female body

During the third trimester of pregnancy, some women feel more and more uncomfortable as they approach their due date. As the baby grows in size and fills the abdominal cavity, some expectant mothers find it difficult to breathe deeply or fall asleep, while others feel uncomfortable waiting anxiously for the birth of their baby.

The following is a list of changes and symptoms that may occur in a woman in the third trimester:

1. increased body temperature,
2. increased frequency of urination returns due to increased pressure on the bladder
3. blood pressure may drop when the child presses against the vena cava that directs blood to the heart
4. swelling of the ankles, hands and face may occur because the pregnant woman retains fluids in the body,
5. hair may start to grow on a woman’s arms, legs, and face due to increased hormonal stimulation of the hair follicles. Hair may also appear thicker,
6. leg cramps may become more frequent
7. Braxton-Hicks contractions (sham labor) may start appearing at irregular intervals in preparation for labor
8. stretch marks may appear on the abdomen, breasts, thighs and buttocks,
9. colostrum may start to leak out of the nipples
10. dry, itchy skin can persist, especially on the stomach, as the skin continues to grow and stretch.
11. female libido (sex drive) may decrease,
12. skin pigmentation may become more visible, especially dark spots on the skin of the face,
13. constipation, heartburn and indigestion may persist.
14. back pain
15. hemorrhoids,
16. varicose veins.

Third trimester of pregnancy – tests

The following tests should be performed in the third trimester:

1. blood count,
2. immune antibodies to red blood cell antigens (testing for serological conflict),
3. HIV test, urinalysis, 
4. ultrasound examination to assess the weight and well-being of the fetus (ultrasound between 28 and 32 weeks of pregnancy), 
5. HBs antigen test (test for hepatitis B),
6. vaginal and rectal culture for B-haemolytic streptococci – Streptoccocus agalactiae (35–37 weeks of pregnancy). If the patient turns out to be a GBS carrier (i.e. the culture is positive), she should be given an antibiotic during labor to protect the child from infection (and infection during delivery is e.g. sepsis).