• Biologically, female fertility is the ability to get pregnant and carry a pregnancy to term. Male fertility is the ability to provide healthy sperm capable of starting a healthy pregnancy.
• A woman's fertility varies through her ovulatory-menstrual cycle. A man's fertility does not vary on a cyclical basis. Both men and women can be infertile or have low fertility. Infertility has many causes, including sexually transmitted infections, disease, environmental toxins, and genetic or physical factors. Some of these can be prevented.
• Fertility naturally declines with age in both women and men, although this decline occurs earlier in women.

Some steps are required to get pregnant.

• Beginning with puberty, girls begin to ovulate; one mature egg (ovule) in each ovulation, until menopause (around 46 to 55 years old).  Boys continuously produce millions of tiny cells called sperm, starting at puberty.
• When a sperm fertilizes an egg (ovule), an embryo can be formed.
• The pregnancy results if the embryo attaches (is implanted in) the lining of the uterus. This embryo will become a fetus if the pregnancy continues.

Before a pregnancy can occur, an egg (ovule) and a sperm should meet.This event is called fertilization. Fertilization can only occur during the fertile phase of a woman's menstrual cycle.

During a woman's fertile phase, one of her two ovaries releases an egg (ovule). This event is called ovulation. During this time, which lasts several minutes, finger-like protrusions (called fimbriae) at the ends of the fallopian tubes begin to move to surround the egg and pull it into the fallopian tubes.

Also, during the fertile phase, the woman's cervix moves into a position that makes it easier for sperm to enter the vagina. The cervix secretes a large amount of clear cervical mucus. This mucus provides nutritional support to allow the sperm to survive for several days. The mucus also provides an environment that helps sperm swim through the uterus, to the fallopian tubes to reach the egg.

During intercourse, sperms are ejaculated near the cervix. They enter the cervix within seconds. If the woman is fertile, some sperm can reach the egg (ovule) from the fallopian tube within five minutes, while other sperm can survive in the less viscous ("fertile type") mucus in the cervix.

Thus, for up to five days after ejaculation, spermatozoa continue to exit the cervix and are capable of fertilizing an egg. Therefore, a woman who ovulates a few days after having unprotected sex may have sperm that remain in the cervix, and these sperm can travel up the fallopian tubes and fertilize the egg.

After ovulation occurs, fertilization should occur within 24 hours, because that is how long an egg (ovule) can survive. Fertilization takes place in the fallopian tubes. Once a sperm has fertilized  the egg, it creates a barrier for other sperm. The fertilized egg continues to move towards the inside of the uterus, propelled by the contractions of the fallopian tube and the cilia (small hair-like strands that appear as small protrusions inside the fallopian tube).

As the fertilized egg (zygote) travels through the fallopian tubes towards the uterus, it undergoes division and growth, a journey lasting approximately five days. The zygote continues to divide until it transforms into a blastocyst, ready for uterine implantation, typically occurring between days 9 and 10.

The blastocyst is an early stage of the pregnancy that occurs after fertilization. It is a hollow ball of cells consisting of an outer layer called the trophoblast and an inner cell mass. The trophoblast eventually contributes to the formation of the placenta, while the inner cell mass develops into the embryo.

Then, we call it an embryo, which is a more advanced stage of development characterized by the differentiation of cells into various tissues and organ systems. It forms from the inner cell mass of the blastocyst and represents the early stage of development of a multicellular organism before it becomes a fetus.

The amniotic sac provides a protective fluid environment for the growing fetus. The placenta supplies the fetus with nutrients and oxygen from the mother and transports waste products.

The umbilical cord is what connects the placenta to the fetus. Human pregnancy lasts 38 weeks from fertilization (approximately 40 weeks from the last menstrual period). The pregnancy is thus divided into three periods of about three months each, called trimesters.

During the first trimester, until the twelfth week, the main organs and major structures of the body are formed: the brain, heart, lungs, eyes, ears, arms and legs.

After the eighth week, the embryo is called a fetus.

And usually around the 19th week, the woman can feel the fetal movements.

During the second trimester, from the 13th to about the 27th or 28th week, the fetus grows rapidly.

In the third trimester, the fetus continues to gain weight and its movements become stronger and more frequent.

Early signs of pregnancy differ from woman to woman and from one pregnancy to another, these include:

• No menstruation
• sensitive or swollen breasts
• sensitive nipples
• frequent urination
• unusual fatigue
• nausea and vomiting
• cramps in the lower abdomen
• feeling of bloating
• changes in appetite

!!! All these signs are not precise and specific only to pregnancy, and can be found in many other situations, so in all cases when there were sexual contacts without the use of contraceptive methods, pregnancy can be expected. Pregnancy can only be confirmed with a pregnancy test, which can be carried out by a healthcare provider or bought from a pharmacy;the usual urine test starts to be positive only 10-14 days after unprotected contact, the blood test - a little earlier at 7-10 days, but no test shows the occurrence of pregnancy immediately after sexual contact!. Teenage girls can go to the nearest YK center, where they can take a pregnancy test for free.

Some women who have learned how to sense when their bodies are ovulating can predict quite well what day their period will come; therefore, they may be aware of a pregnancy as soon as their period is late.

A woman's body changes a lot during pregnancy. These changes begin very early, even in the first weeks of pregnancy, and prepare the mother's body to cope with the needs of pregnancy, birth and the postnatal period. These are normal changes, but they can be uncomfortable at times. Changes will occur in almost every organ system.

Most of the changes are determined by the hormones produced in the placenta (a new organ that appears only during pregnancy). In other words, hormones are natural chemicals produced by one part of the body that tell different parts of the body what to do. The most important hormones in pregnancy are called estrogen and progesterone. There are also hormones that do not come from the placenta, but are of great importance. One is called oxytocin - sometimes called the love hormone and prolactin which is also called the milk hormone.

As mentioned, all changes are aimed at making pregnancy and birth safe. To grow a child,  the pregnant woman needs additional food. The gut slows down its movements and it can absorb more nutrients; this is good for pregnancy, but it can cause constipation.

The baby needs oxygen, so the lungs breathe deeper, but not faster. This is good for the baby, it will feel shorter breathing. Oxygen has to be carried in the blood from the lungs to the placenta, so the heart has to beat more often to carry the necessary amount of blood and oxygen, thus it can cause palpitations.

The growth and intrauterine development of the baby is hard work and hard work produces a lot of thermal energy. To get rid of this heat, the body must transport it to the skin, and therefore more blood will reach the skin. It is possible to have more frequent sensations of heat, and more excessive sweating.

When the baby is born and after the birth (placenta) there is always some bleeding. To prepare the body for this, it produces extra blood. This extra blood should be "stored" somewhere until needed. It can only be stored in the blood vessels and therefore the blood vessels have to dilate, so you may have dilated blood vessels on the legs, called varicose veins or dilated blood vessels around the anus, called hemorrhoids.

In the case of a natural birth, the baby will have to come out through the vagina. For this to happen, the tissues around the vagina should expand. The body will prepare for this by making the ligaments that join the bones and the skin more flexible, softer. This is beneficial for childbirth, but the loose ligaments can cause back pain and the skin can have stretch marks.

Soon after birth, the baby should be breastfed. The body prepares for this by growing the breasts during pregnancy and preparing them to produce milk. It's good for the baby, but it can cause breast tenderness, larger breasts, the need for a new bra, and nipple discharge.

Other changes during pregnancy do not have a very clear purpose, for example, the skin can darken, vaginal secretions are more abundant, urination is more frequent, leg cramps and morning sickness (feeling like throwing up or nausea, and throwing up or vomiting). All these changes are normal, as long as the pregnant woman does not feel extremely uncomfortable and cannot take care of basic daily activities because of them.

Most changes completely return to their previous state after pregnancy.

If a woman or girl chooses to keep her pregnancy, it is especially important for her to go to the family doctor or a YK center, as soon as possible, in order to receive antenatal care necessary for the normal course of the pregnancy and preparation for birth (see more on the Antenatal and Postnatal Care section)