Pregnancy Trimester by Trimester

• Pregnancy officially starts from the first day of a woman's last menstrual period (LMP). The inner lining of the womb prepares to receive a fertilised egg between ovulation and menstruation.
  
• All the genetic material that will be baby's blueprint for life is contained in the rapidly dividing ball of cells.
  
• An ultrasound scan shows rudimentary signs of pregnancy from about 3 weeks after conception
  
• Cell division is an on-going process and soon a mulberry like cluster of almost-transparent cells, called a ‘morula' forms.
  
• A quantitative blood test shows the pregnancy hormone HCG* within 24 hours, although at this stage there is still significant room for error.

*Human Chorionic Gonadotropin (HCG) is a pregnancy hormone produced by the immature developing placenta as soon as the fertilised egg cell implants in the endometrium. HCG levels in mother's urine and blood can confirm pregnancy with great accuracy if done at the correct time.

The cell cluster doubles in size every day at this stage with about 1,000 cells in the cluster by the end of this week.

• The cell cluster starts to form an inner and outer group.
  - The inner cluster will become the budding embryo, your baby-to-be.
  - The outer group of cells become the placenta and other pregnancy support structures.
• The sense of touch develops one month after conception and is crucial for brain development and emotional well-being of the unborn baby.
• The placenta develops by growing protrusions that imbed in the blood rich inner wall of the womb and will soon take over the vital functions to keep baby alive and thriving.

Your baby is starting to form. The cell structure forms a third layer and different cells start developing differently to fulfil various, specific roles.

• The top layer of cells is called the neural tube and becomes the brain, the spinal cord, the nerves, and the skin.
  
• The digestive system forms from the central layer of cells.
  
• The bottom layer of cells gives rise to vital organs like the heart, to the muscles and the skeleton.
  
• The part of the embryo called the yolk sac produces blood cells but it isn't a yolk at all.

Baby can easily be seen with the naked eye at this stage and is slightly starting to wiggle.
I'm going through changes…tiny changes

• The breathing and digestive systems are still not differentiated and exist as a single tube.
  
• The inner structure of the lungs starts developing this week.
  
• Baby's heart is about 2 millimeters from top to bottom and can be seen beating on ultrasound between six and eight weeks.
  
• By the end of Week 6, the embryo is 4 millimeters long.

Twins are the most common multiple pregnancy, with an incidence of about one in 90 to 100 births. More black than white women giving birth to twins.

Triplets are fairly rare at one in about 9 000 pregnancies and quadruplets, quintuplets and so on even less frequent.

Multiples, other than twins, are nowadays more often than not the result of fertility drugs, occurring very rarely naturally.

My changes are getting bigger!

• While baby's arms continue to develop during this week, leg buds also emerge along with rudimentary hands that look like paddles.
  
• Folds of tissue can be noticed on the head will become chin, cheeks and ears. At this stage the mouth is just a hollow in the head.
  
• The main air pipe called the trachea and the gullet or oesophagus now begin to separate into two distinct tubes.
  
• The brain was the first organ to develop and in this week alone has increased in size by 25 percent being the most developed organ.
• Baby appears to have a tail but this is an extension of the spine that will disappear.

I'm officially a fetus and a complete little human being!
Fetus means “offspring” or “young one”.

• The head is now about half the length of baby's body and baby's forehead bulges prominently. At birth the head will be one quarter of baby's total body length.
  
• The babies face starts to take form. The upper and lower jaws form this week with the first hint of eyes that can be seen at the sides of the head. By the end of this week, baby sprouts a slight bulge on the face that will become the nose and small shell-like outer ears now develop, emerging from low on the head.
  
• Milk teeth start forming in the sockets in the jaw.
  
• The babies most vital part of its immune system starts forming in the form of bone marrow that will manufacture blood cells.
• Arms and legs now grow rapidly with little fingers and toes forming from the babies paddle like hands and feet.
  
• To add to the rapid growth spur, the intestines and kidneys develop, muscles form around the soft cartilage that will soon harden into bones.

The heart has developed two chambers from the single tube and will eventually have four.

• The legs are bent at an angle so that the soles of the feet face each other.
  
• Cartilage skeleton is now being systematically replaced by bone cells, but will only harden shortly before birth.
  
• The babies tiny arms now start bending by the elbow.
  
• On the inside of the babies developing mouth, the tongue is now starting to form.
  
• The babies head is now beginning to appear rounder with the eyes that are slowly making their way to the front of the face.

• he babies heart has now fully developed with four heart chambers and is beating between 120 - 140 beats per minute. On an ultrasound it looks like a flashing asterisk.
  
• Eyes are not fully developed with tiny details like the eye pigmentation and eyelids forming.

• The liver starts to produce red blood cells that now flow through major blood vessels, an important part of the circulatory system.
  
• Although still not in the final position, the full ear is now developed, all the way down to the small inner, middle and outer ear.
  
• Brain waves can now be measured on an electro-encephalogram (EEG).
  
• Muscles in the trunk, head and limbs rapidly develop and larger muscles are now able to contract.

• The babies liver is now large, making up 10% of the babies weight and blood circulation removes waste products from the ever growing baby.
  
• Major development in the babies head starts to take form, the baby's head is now rounder and slowly stops getting bigger. In the mouth, the palate forms as well as rudimentary sockets for adult teeth are already taking shape below the milk teeth.
  
• Within the abdomen, the intestines rotates and sets in place with the now developed diaphragm dividing the chest from the abdomen.
  
• The baby's body begins to grow and quickly becomes double the size of the head.

• Although structure and function of organs still need to grow and mature, most of them now begin primitive functioning.
  - the pancreas manufactures digestive enzymes and insulin. - the thyroid is also functioning on its own.
  - lungs are slowly developing with early chest movements beginning, preparing the baby for breathing.
  
• By week 12, the perfect but skinny baby is surrounded by 50 cubic cm of amniotic fluid that it now begins to swallow to nourish its growing body and assist in its growth.
  
• The baby's iris is also now fully developed.

Your baby is now 9cm long in average and weighs between 55 and 60 grams!