How a baby is formed – Part 1


The birth of a child brings joy and gladness within the family. To others, it is deemed a miracle but with science, there have been investigations into some of the major processes involved to unravel some of these mysteries. It has informed the decisions and selections a person makes. In this article, we shall have in-depth knowledge about the journey to birth.

Basically, the two items needed to form a baby is a single sperm and an egg. There are about 40 million sperms deposited during a single ejaculation however, only one can make it.

The first obstacle is the acidity in the vagina. The sperm is enriched with fluids that can neutralize the acidity as it passes through however, not all make it.

The next obstacle is the mucus in the cervix. The cervix is the opening of the uterus(womb). It has crevices and mucus that can trap some of these sperms. However, during ovulation, the cervical mucus becomes thin and stretchy to facilitate the swift movement of the sperms. Regardless, only a thousand to ten thousand sperms are able to make it into the uterus. The immune system protects the uterus hence, some of these sperms are defeated. The ones that survive are enriched with fluids that makes them super mobile and capacitated. They are the ones that travel to the fallopian tube to meet the egg.

Remember, the egg is released into the fallopian tube. Hence, the sperms must travel upwards to reach the fallopian tube.

There are two fallopian tubes, a right and a left side. An egg is found only in one part of these sides hence, most of the sperms will miss. Exceptions are in the case of unidentical twins where the ovaries release two eggs, one on the left and the other on the right. In this instance, the sperm that first meets each of these eggs will be the one to fuse.

The sperm travels to the egg and only the head fuses with the egg to begin the process. This is because, the head of the sperm contains the chromosomes and genetic material, all the other components such as the tail and middle part propel the sperm to successfully reach the egg. Once the single sperm fuses with the egg, all the others are rendered useless by the actions of the female egg. The egg responds in two ways, a fast reaction and a slow reaction. Immediately the egg fuses with the first single sperm, an electrical potential(charge) is generated that prevents the other sperms from penetrating the egg. However, this charge created does not last, hence, the second reaction which is a slow response comes in.

The human child undergoes 4 main developmental stages:

1. Zygote- this happens when the fusion between the male and female gamete is completed.

2. Blastocyst- the zygote begins to divide and forms a hollow wall of cells called a blastocyst. It is this blastocyst that attaches to the lining of the uterus.

3. Embryo-this term is given when the major internal and external organs begin to form in the first trimester. e.g., heart, brain, etc.

4. Fetus- this is when the features of the embryo begin to grow, develop and differentiate. This happens usually in the third month.

To understand the developmental stages, we will divide the stages into three trimesters.

First trimester-(Week1-Week12)

Processes in the womb;

A human cell begins with a single cell from both parents but develops into trillions of cells over 9 months. The sperm and egg fuse to form a zygote. The single-celled zygote which is enclosed in a wall called zona pellucida divides into two, four, eight, 32 and so on to form a mass of cells with a cavity called a blastocyst.

The division of the blastocyst occurs as the cell moves from the fallopian tube into the uterus. All this while, it has been relying on the nutrient in the uterine environment but this is not enough to sustain it. The blastocyst has numerous inner cells separated by a cavity and an outer layer but this is still enclosed in the wall, zona pellucida. The wall hatches and releases the blastocyst.


The outer layer attaches to a location in the uterus(womb) and forms the placenta while cells inside the blastocyst develop into the baby. The inner cells become more distinct and is termed embryo. Hormones, progesterone and estrogen are secreted to nourish the embryo by cells in the ovary.

After implantation, special networks begin to form between the embryo and the attached outer layer through which blood from the mother starts to flow. Human chorionic gonadotropin (hCG) is produced by the outer layer that is now attached to the uterus which later forms the placenta. It informs the body to continue producing progesterone to prevent you from releasing another egg. Contraceptives use the same mechanism; the pills and drugs make your body continue producing these hormones as if you are already pregnant thus, your body is deceived and fails to release an egg. Furthermore, during pregnancy test such as urine test, it is the presence of this hormone, hCG that determines whether your test comes positive or negative. hCG present means a person is pregnant whilst the absence means otherwise.

If a human is formed from one cell, then how come, we all have different systems? This is your answer.

As the human implants in the uterus, the inner cells become very distinct and form three germ layers; endoderm, mesoderm and ectoderm. It is out of these three germ layers that the human body differentiates and forms different parts of the body. For instance, the endoderm forms the interior linings of all your organs. The ectoderm forms the nervous system; brain and spinal cord and skin whilst the mesoderm forms the blood vessels, bones and muscles.

At the end of the first month, the following are formed:

1. The major systems and organs.

2. The embryo looks like a tadpole.

3. The neural tube which becomes the brain and spinal cord, the digestive system, the heart and the circulatory system begin to form.

4. The eyes and ears begin to form.

5. The precursor of the legs and arm, limb buds appear.

6. The heart starts to beat.

In the 8th week:

· The major body systems continue to develop and function, including the circulatory, nervous, digestive, and urinary systems.

· The embryo is taking on a human shape, although the head is larger in proportion to the rest of the body.

· The mouth is developing tooth buds, which will become baby teeth.

· The eyes, nose, mouth, and ears are becoming more distinct.

· The arms and legs can be easily seen.

· The fingers and toes are still webbed but can be distinguished.

· The main organs continue to develop and you can hear the baby's heartbeat using an instrument called a Doppler.

· The bones begin to develop and the nose and jaws are rapidly developing.

· The embryo is in constant motion but cannot be felt by the mother.

In the 12th week, the embryo has termed a fetus and has the appearance of a human being.

· The external genital organs are developed.

· Fingernails and toenails appear.

· Eyelids are formed.

· Fetal movement increases.

· The arms and legs are fully formed.

· The voice box (larynx) begins to form in the trachea.


The first trimester is the period where most miscarriages happen. The major organs and the outline of the human body form at this stage hence exposure to radiation, alcohol, pathogens, and toxic substances may result in miscarriage.

Also, a woman may avoid all these harmful items but when the blastocyst fails to move down into the uterus and attaches in the fallopian tube, there would be complications and is called an ectopic pregnancy.

Furthermore, a woman must eat well-balanced diets and be on appropriate supplements such as folic acids prescribed by a doctor to facilitate the well-being of her unborn baby. Other complications may arise due to stress, genetics and lifestyle. Adequate rest and comfort are recommended during this fragile stage.


To avoid complications and ensure the smooth growth of your baby, a check-up is necessary. A full medical test together with family history is taken. Lab tests including urine and blood test are performed. The blood test is very important as it determines the rhesus factor (Rh) of the mother and avoids major complications. Pregnant mothers are most importantly educated on pregnancy and how to cope during each stage.

Pregnancy is a good thing for married couples longing to have children but the discomforts these women undergo sometimes is unbearable. The body changes to accommodate the baby. The breasts will begin to enlarge and become tender to prepare the woman for breastfeeding due to the increase in estrogen and progesterone. The areolas darken to help the baby identify the tip of the breast for effective breastfeeding when it arrives. The uterus enlarges and begins to press on the bladder which makes pregnant women urinate often and may result in constipation when it presses on the rectum and intestines.

Surges in hormones may cause irritability and “morning sickness”.

Fatigue may set in due to the physical and emotional demands during pregnancy.

Some may experience many of these symptoms whilst others will experience little to nothing. Regardless, attention and care must be given to pregnant women to ensure the arrival of a safe and healthy baby.

Watch out for the next episode on pregnancy!



A young lady who is excited to influence the society and world with the knowledge she has acquired.