Advertisement - Scroll to continue

What is Pregnancy?

Pregnancy is the state in which a woman finds herself from the moment of union of the female reproductive cell – the egg cell with the male reproductive cell – sperm and the implantation of the fertilized egg in the uterus.

The woman’s reproductive system comprises the ovaries, fallopian tubes, uterus, and vagina. The fertilized egg will develop inside the uterus. In the first two months, it is known as an embryo and, after that, as a fetus.

The umbilical cord connects a fetus to the placenta. The placentaTrusted Source is an organ responsible for the blood flow between the mother and the baby. The uterus is entirely of amniotic liquid, which keeps the fetus hydrated and maintains its temperature. This liquid also assists with the unborn baby’s lung and digestive system growth and development.

Pregnancy: What Is, Tests, Calculator, and Symptoms

Pregnancy in humans typically lasts for nine months, which equates to forty weeks. This period is divided into three trimesters – the first ending after twelve weeks, the second concluding at twenty – seven weeks, and the third culminating with the delivery of the infant.

It is often hard to pinpoint the exact time of fertilization, commonly seen as the commencement of pregnancy. Therefore, the first day of a woman’s last menstrual period is considered the beginning of pregnancy.

Symptoms of Pregnancy

At the beginning of pregnancy, before symptomsTrusted Source appear, it is difficult for a woman to feel changes in her body. It is only when troublesome symptoms appear that many women reach for pregnancy tests or go to the doctor to find out they are pregnant.

Symptoms include:

Pregnancy Tests

In the first week after conception, it is impossible to diagnose pregnancy based on an ultrasound examination.

A pregnancy test to check hCG levels can be done from urine and in the laboratory in blood.

Another blood test that can detect pregnancy is the Early Pregnancy Factor (EPF)Trusted Sourcetest, which, unlike beta-hCG, can be seen as early as 48 hours after conception.

Calculating Due Date

The delivery date is one of the most essential information for a pregnant woman. When confirming a pregnancy, a woman often wants to know when her child will likely be born.

Remember that most babies aren’t born at exact terms – they come to this world before or after this date, and some are born prematurely, i.e., before the 37th week of pregnancy.

The doctor determines the approximate delivery date during the first visit during pregnancy. Then the doctor will ask you about the first day of your last menstrual period and, on this basis, will calculate the due date.

Knowing the date of the last menstrual period, you can use Negele’s ruleTrusted Source  to calculate the due date:

  1. Take the first day of your last menstrual period.
  2. Subtract three months.
  3. Add one year and seven days. 

However, this rule only applies to regular (28-day) menstrual cycles. If the menstrual cycles are longer or shorter, add or subtract days from the calculated date accordingly.

It should be remembered that the calculated due date should be verified during an ultrasound performed in the first trimester of pregnancy, preferably before the 10th week. During this time, every baby grows the same; only later in pregnancy can children develop at different rates.

The First Trimester

Week 1

Fertilization usually occurs in the fallopian tube (the tubular structure that connects to the uterus). A zygoteTrusted Source is formed when a female reproductive cell fuses with a male reproductive cell. The zygote moves from the fallopian tube to the uterine cavity. During this time, it undergoes multiple divisions. When it reaches the uterine cavity (3-4 days after fertilization), it already consists of 12-16 cells.

Implantation Trusted Source occurs in the uterus between 6 and 7 days after conception. On the day of implantation or the next few days, a woman may experience spotting or bleeding – this is known as implantation bleeding.

Weeks 2-8

The embryonic period begins in the third week of pregnancy and ends in the eighth week. It is called the stage of organogenesisTrusted Source because it is during this time that most organs develop.

This stage of development is characterized by the rapid growth of the embryo, and the effect of a fetus-damaging factor (so-called teratogensTrusted Source, e.g., alcohol, cigarettes, radiation exposure) during this period may lead to miscarriage or severe developmental defects.

The heart is the first organ to start working in the embryo’s body – it starts beating in the 4th week. In fetal life, the heart beats much faster – 120 to 160 beats per minuteTrusted Source are considered normal, which is more than twice as fast as your heart.

At the end of the second month of pregnancy, the embryo is about three centimeters long and weighs about ten grams – the size of a grape. On its disproportionately large head, you can see the eyes and outline of the nose. Fingers and toes can be seen on the limbs.

Weeks 9-13

From the 9th week of pregnancy, the developing baby is no longer called an embryo but a fetus, and fetal development begins.

By the end of the third month, the fetus has a developed muscular and nervous system. Its sex organs are also formed, although it might be difficult to determine gender on ultrasound at this time. It reacts to stimuli and moves its limbs, although the mother does not yet feel the movements. Nails appear on the fingers and toes. The fetus is about 10 centimeters long and weighs about 30 grams – the size of a kiwi.

The placenta is fully developed at the end of the 12th week.

The Second Trimester

Weeks 14-17

During the 4th month of pregnancy, the following processes take place:

Weeks 18-22

At five months, around 20 weeks, the mother begins to feel fetal movementsTrusted Source. Women who have already been pregnant may start feeling them about two weeks earlier. Movements are significant evidence of a baby’s well-being, so monitoring them is essential. 

Weeks 23-27

At the end of the sixth month, the proportions of the fetal body are like those of a newborn. 

From the 24th week, babies born prematurely have a chance to survive. Earlier, this was not possible due to the need for sufficient development of the lungs.

Pregnancy: What Is, Tests, Calculator, and Symptoms

The Third Trimester

Weeks 28-31

The baby’s fat tissue grows significantly in the seventh month of development. It becomes less wrinkled and more plump. The fetus develops a sucking reflex and reaches a weight of around 1200 grams – a papaya size.

Weeks 32-40

In the last two months, the growth of the fetus in length is slower, but it gains significantly in weight. 

During that time, the testicles descend into the scrotum in male babies. Meconium is produced in the baby’s intestine – a mixture of amniotic fluid and skin cells. This will be your baby’s first poop after birth. The birth weight of a baby is around 3000-3600 grams. At birth, the organs of a full-term newborn are mature enough to take up their functions. The most critical reflexes for survival outside the mother’s organism are also developed. 

Most women give birth before 42 weeks. However, if you don’t go into labor by then, you’ll probably be induced, as carrying a pregnancy past that time can be dangerous for your baby.

Changes in The Mother’s Body

During pregnancy, the adaptation of a woman’s bodyTrusted Source is enormous. Many changes begin as early as conception and continue throughout pregnancy. Most of the changes seen during pregnancy are almost immediately reversed after delivery. The most significant of these changes include:

The increased amount of blood

Blood volume begins to increase by approximately 15% in the first trimester and peaks in the third trimester (about a 40% increase compared to a non-pregnant woman)

An increased heart rate

Mothers’ heart rate increases by about 20 beats per minuteTrusted Source as early as five weeks into pregnancy. Changes in the circulatory system arise because the mother’s body must supply, apart from itself, the developing child.


Edema means swelling due to fluid retention in some part of the body. In pregnancy, swelling mainly affects the legs. There are several causes. During gestation, the concentration of hormones progesterone and estrogen, which affect the tension and permeability of blood vessels, increases significantly. In addition, the pressure of the enlarging uterus on the blood vessels obstructs blood flow. It causes blood stagnation in the lower parts of the body. 

A decreased blood pressure

The placenta produces an abundance of the hormone progesterone while a lady is pregnant. It is a hormone that allows you to maintain pregnancy and causes muscle relaxation, including the muscles of the walls of blood vessels, consequently reducing the pressure in the vessels during pregnancy.

Feet growth

Many women’s feet growTrusted Source along with their growing belly. Sometimes, it is even necessary to buy new, bigger-sized shoes. One of the causes of this phenomenon is the increase in pregnancy hormones (relaxin), which causes the ligaments in the feet to loosen. In addition, the feet have to bear more weight and are heavily loaded due to incorrect body position.

Blocked nose

The large amounts of estrogen and progesterone cause swelling of the nasal mucosa, which in turn promotes the feeling of nose blockageTrusted Source. It mainly affects women in the final stage of pregnancy and resolves within two weeks after delivery.

Supplements and Nutrition During Pregnancy

When expecting a baby, a woman’s body’s need for specific vitamins and mineralsTrusted Source rises. Supplementation during pregnancy is recommended for all pregnant women. It is essential to choose a preparation that contains nutrients in appropriate doses that are crucial for the proper development of the fetus and the course of pregnancy.

A balanced, nutrient- and vitamin-rich diet is recommended during pregnancy. This allows you to meet the demand for most of the necessary ingredients. Caloric needs increase during pregnancy. You need an extra 400 calories dailyTrusted Source in the second and third trimesters.

Pregnancy: What Is, Tests, Calculator, and Symptoms

Woman’s Age and Pregnancy

Nowadays, pregnancy after the age of 35 is a complete norm. It is worth remembering, however, that as a woman ages, the risk of complications increases and fertility decreases. 

According to experts, the biologically appropriate time to become pregnant is between 20 and 25Trusted Source. This is when women are most fertile and tolerate all changes in their bodies well, and the risk of miscarriage is the lowest at this age. In addition, there is a much lower probability of having a child with genetic defects than older women.

Having a baby after the age of 35 is challenging. This is due to reduced fertility and more significant problems with maintaining pregnancy. Every woman over 35 expecting a child should undergo prenatal tests to rule out genetic defects.

Getting pregnant after age 40 is complex, and success depends on the ovarian reserveTrusted Source, which is the number of eggs left in the ovaries. Its happy ending is also not sure. The expectant mother also has to consider potential complications, like the risk of giving birth to a premature baby. The very high risk of genetic defects Trusted Sourceshould also be taken into account.

What Tests Should be Performed?

Thanks to regular tests, the risk of dangerous complications for the mother and her baby is reduced. Doctors can detect abnormalities very early and implement appropriate therapeutic measures. Screening during pregnancy reduces maternal deaths, perinatal mortality, and preterm birth rates.

What are the testsTrusted Source routinely performed during pregnancy?


July 11, 2023
14 minutes read

Table of Contents

Find a topic by its first letter
Pregnancy Symptoms: 15 Early Signs of Pregnancy
15 Early Signs of Pregnancy

Do you know what pregnancy symptoms appear early? Hormonal changes can cause various symptoms of pregnancy. Find out what signals… read more »

Gestational Diabetes: What Is, Causes, Diagnosis, Treatment, and Complications
Gestational Diabetes

Gestational diabetes is a condition in which the blood sugar levels are high during pregnancy. If left untreated, it can… read more »

Ovulation: What Is, Symptoms, Monitoring, and Tests

Ovulation is a key stage of the menstrual cycle in which the mature egg moves into the fallopian tube. What… read more »

Genital Herpes: Symptoms, Helpful Prevention, and Treatment
Genital Herpes

Genital herpes is a disease caused by the HSV herpes virus. What symptoms does it give? Check what treatment and… read more »

Adenomyosis: What Is, Causes, Symptoms, Diagnosis, and Risk Factors

Adenomyosis is a chronic disease that can significantly reduce a woman’s quality of life and limit her fertility. Learn how… read more »

Rubella: What Is, Causes, Symptoms, Diagnosis, and Treatment

Rubella is an infectious disease caused by a specific type of virus. It is most commonly diagnosed in children. Find… read more »

PCOS: What Is, Symptoms, Diagnosis, and Treatment

Polycystic ovary syndrome (PCOS) manifests itself with a number of physical and psychological symptoms. It is caused by hormonal disorders. read more »

Mastitis: What Is, Causes, Symptoms, Diagnosis, and Treatment

Mastitis is a condition that can affect many women, especially during the postpartum period. What symptoms does it cause? What… read more »

Down Syndrome: Causes, Characteristics, and Medical Care
Down Syndrome

Down syndrome is a set of features that are the result of the presence of an extra chromosome 21 in… read more »