When you become pregnant you experience many incredible changes over your pregnancy.
Here we look at week by week changes you will experience and developments in your womb.
Development of the Zygote
Day 1. During sexual intercourse Approx 300-500 million sperm are deposited in the female genital tract… But only about 300-500 reach the area of fertilization. Fertilization occurs closest to the ovary. This is in the widest part of the fallopian tube.
Once a sperm penetrates the egg, the surface of the egg changes to prevent multiple fertilization. The sperm and the egg begin to fuse together.
Day 2. The sex is determined after the sperm and egg have fused. The cell eventually splits into two cells. This two-cell stage occurs about 30 hours after fertilization.
Day 3. About 3 days after fertilization The 12- and 16- cell stages occur . This small clump of cells is referred to as the morula.
Day 5. About the fifth day the morula finally enters into the uterus. Fluid begins to enter until a single cavity is formed. When this cavity is formed, the embryo is called the blastocyst.
Day 7. Around day 6… Implantation into the uterine wall begins . The uterine lining is in a secretory phase at this point. The wall becomes spongy as the glands and arteries become coiled.
Week 2 – 4
Approx 22 days after conception your baby will have developed a heart beat, and is on its way to developing the digestive tract, sensory organs, and neural tube. The neural tube is what eventually becomes the Central Nervous System, consisting of the spinal cord and brain.
By the end of the first month of your pregnancy, your baby is smaller than a grain of rice.
What You might be Experiencing
- frequent urination possibly with vomiting
- absence of menstruation
- emotional changes similar to PMS
- tenderness and fullness of breasts
- food cravings
It is highly possible that you do not know that you are pregnant during the first couple weeks. However, It is possible that you will experience some of the signs of pregnancy.
The embryo is attached to the lining of the uterus and is about 3 mm in length. You could see it with your eyes.
The amniotic sac will have been formed.
The embryo is not recognisable as a human being. But it has a spinal column, a large head and arms and legs. The sockets for its eyes have been formed. It is 1.3 cm long.
You may start to experience some symptoms such as breast tenderness and morning sickness.
The embryo has all his or her major organs. The toes, fingers and features on the face are in the process of forming. The embryo is now considered a foetus. It is now more recognisable as a human. The length is about 2.5 cm.
Fingers and toes are now webbed, the head remains larger than the body part. It has blood circulating through it.
The uterus can just be felt above the pelvis. The foetus is about 7.5 cm long. It is more active. Nails and genitals are starting to appear.
You probably do not suffer from morning sickness any more.
Your nipples may darken in colour and your breasts may stop feeling quite so tender. You will probably start to show from this time onwards.
The foetus is moving vigorously but you may not be able to feel it.
The uterus will have reached to level of your navel. You will now be able to feel the movements. The foetus now measures about 21 cm and is covered with fine hair. Eyelashes and eyebrows now have developed.
Your foetus eyelids separate. Its length is about 33 cm
The uterus reaches about halfway between the navel and the breastbone. If the foetus was born now, it could survive. It measures 37cm. The head is now reasonably in proportion to the body.
The foetus is still very active. Most babies will have their head in the birth position.
In most women, having babies for the first time, the head will have descended into the pelvic cavity and the uterus descends from under the rib cage as the baby’s head has moved down into the pelvis. It is about 46 cm.
Pregnancy is full term. You can now breath easier, although you still may have pressure on your bladder