The first week, there is an explosion of life happening inside your body! You have successfully conceived. Despite what you may have heard, there are unbelievable changes and developments happening right away, because life has emerged.

Week 1

In general, it is difficult from a healthcare standpoint to pinpoint the moment of your conception. Because of this, there are not many articles referencing the first week of pregnancy. Most healthcare providers (doctors, OBGYNs, etc.) only count the 40 weeks of pregnancy counting back to the first day of your LMP (last menstrual period). This is how they figure out your due date. By doing this, however, it could technically be up to two weeks before the actual moment of conception occurred. Regardless of how your healthcare provider calculates your due date, you still had a first week of pregnancy, obviously!

Life Finds a Way

Whether your pregnancy was planned, or an unexpected surprise, life has found a way. The changes may be yet to come, and the responsibilities of parenthood may be far off – but these things are on their way! You see, you moat likely will have no idea you are pregnant in your first week. In fact, you most likely will not have known until your fourth week of pregnancy. But regardless of when you actually find out that you are pregnant, you did have that first week. It was in one powerful moment that life suddenly came into being. Within about 30 hours after conception, the zygote (the single cell embryo) begins its first cellular division through what is known as mitosis.

From Fertilization to the First Cell Division

Fertilization, also known as conception, is the first step in human development. It occurs within the first 24 hours after ovulation. This most commonly happens in the ampulla, or the outer third of the uterine tube. It is here that the sperm and the egg (or secondary oocyte) combine.

The exact moment of conception occurs when the sperm makes first contact with the cells which surround the oocyte, and finishes when the male’s 23 and the woman’s 23 chromosomes blend. The end result is a zygote, also known as a single-cell embryo. It is the very first cell of a human being.

Now, the zygote is surrounded by a protective film called the zona pellucida, and it has 46 unique chromosomes. In fact, the whole genetic blueprint for this unique, brand new person is already engrained in this single cell through DNA. Each chromosome holds compact molecules which are DNA. As we all know, DNA holds the data which, through time, causes this single-cell embryo to eventually form into a fully functioning adult man or woman.

The ending stages of the zygote arrangement, is the replication of the DNA. It also represents the alignment of the chromosomes as it readies for its very first cellular division process through what is known as mitosis. This is where the chromosomes form a cleavage spindle – the first phase of mitosis. Each set of chromosomes travel to the opposite sides of the zygote. It is here, that a line begins to emerge along the center of the zygote. After about 30 hours after conception, the embryo splits into two cells in what is known as cell division. Cleavage is the repeated process of this development through division. And that’s just the beginning…

This first week, your baby’s sex is already decided. In addition, the brain, heart, and spine is already being formed as well. All in only the first week. At no other point during your pregnancy will your baby develop at such an accelerated rate. Your baby is on its way!