Pregnancy Process: How Is a Baby Formed?

“Where do babies come from?” You have probably asked your folks some variation of this. If you’re reading this site, we assume you already know the basics on what happens when a mommy and daddy love each other very much.

But seriously: how exactly does the process of getting pregnant work? Unless they’ve studied it in depth, a lot of women would have trouble explaining the pregnancy process in greater detail. Let’s break down the steps of what’s happening in your body each step of the way.

The Pregnancy Process Explained! Step 1: The egg matures

female reproductive system

A woman is born with all the egg cells she is ever going to have in her life: roughly 1 to 2 million. These are all found in the ovaries – the two oblong-shaped organs on each side of the uterus. When puberty kicks in, the pituitary gland releases hormones that cause 20 to 30 of these follicles (cellular structures surrounding the immature eggs) to start developing each month. Of these, only one follicle will fully mature each cycle.

Step 2: Ovulation

woman pregnancy hands heart

Once the mature follicle is about 18 to 20 mm in diameter, a surge of luteinizing hormone causes the follicle to rupture, and the ovum (egg cell) pops out. The rupture of the follicle can also cause some mild cramping and bleeding, usually called “ovulation spotting”.

The egg is then sucked out of the ovary by projections called fimbriae, and enters the fallopian tubes. This process is called ovulation, and takes place once every month. The unfertilized egg is able to survive for about 24 hours.

Step 3: The sperm moves in

human sperms

Let’s say a woman and her partner have themselves some good old penis-in-vagina sexual intercourse. When the semen is ejaculated into the vagina, the sperm cells inside travel towards the fallopian tubes at a speed of about 2 to 3 millimeters per minute. This is quite impressive considering that the average sperm cell is only about 50 to 55 microns long!

The sperm travel through the cervix (the opening at the innermost point of the vagina) and into the upper part of the uterus, but 99% of them die in the long journey toward the fallopian tubes. Only about 200 sperm cells reach the fallopian tubes, where the egg lies in wait.

Step 4: Fertilization


The 200 or so sperm cells that reach the fallopian tube surround the ovum and attempt to break through its protective coating through a chemical process called the acrosome reaction. A single sperm cell is ultimately able to break through and fuse with the inner membrane of the egg, allowing the contents of the sperm cell to enter the ovum.

When this happens, this egg is then said to be fertilized. Vesicles in the egg called cortical granules then burst, a process that prevents the other sperm cells from entering. Approximately 28 hours after fertilization, cell division begins, and the fertilized egg – now called a zygote – makes its way down the fallopian tubes.

Step 5: Implantation – the pregnancy process is complete!


Over the next 7 to 10 days, the zygote undergoes round after round of cell division as it slowly makes its way through the fallopian tubes and toward the uterus, forming a lump of cells that will become known as a blastocyst. When this bundle of cells reaches the uterus, it continues to divide and grow until it finally lodges itself into the endometrium lining of the womb.

This process is called implantation – the last step in the process of getting pregnant. After this, the implanted mass of cells will continue to develop and grow, eventually becoming an embryo, then a fetus, and finally a tiny human.

The more you know about the pregnancy process…

pen dictionary

How was that for a crash course in human reproduction? We tend not to think about what’s going on in our bodies at this level on a daily basis. But the more you think about it, the more mysterious and beautiful the process of pregnancy seems to become. Now you know the basics that go into having a baby, why not share it with your partner? When your baby comes into the world, you’ll be able to look back and recall how it all began.