A week-by-week pregnancy calendar

Embryonic phase:

• Week 1: the average crown length is 0.5mm;
• Week 2: the average crown length is 2 mm;
• Week 3: the average crown length is 3 mm
• Week 4: the average crown length is 4 mm and the average weight of foetus is 0.4 g;

Seven days after ovulation, the fertilized egg gradually implants itself in the uterus. By the 10th day, the embryo appears. Its inner cells form two, and later, three layers. The first grows into the skin, eyes, brain and nerve centre; the second, the foetal digestive organs and the lungs; while the third, its blood, muscles, heart and bones.

• Week 5: the average crown length is 5-8mm;
• Week 6: the average crown length is 10-14 mm;
• Week 7: the average crown length is 17-22mm;
• Week 8: the average crown length is 28-30mm and the average weight of foetus is 2g;

The first heartbeat. Larger organs begin to take shape and form as the brain, facial features and limb joints become visible. Finally, pregnancy can be confird by sonar.

Foetal phase

• Week 9: 10 g and 5 cm;
• Week 10:
• Week 11:
• Week 12: 19 g and 8cm.

Now known as a foetus, and with a defined gender – its ears, nose and mouth take form on its relatively large head. The newly shaped eyes are covered with a skin that will soon become the eyelids. Arms and legs lengthen as the nails begin to grow. The foetus’s heart now beats as just 170-175 per minute.

• Week 13: 9 cm;
• Week 14: 45 g;
• Week 15:
• Week 16: 100 g and 14 cm;

Large organs now fully formed. Coordinated by its brain, the foetus can now stretch its arms and legs, and open its mouth – in which 20 little teeth are already in place. Its face becomes more defined while the rest is covered with soft downy hair known as lanugo.

• Week 17: 15 cm;
• Week 18: 200 g;
• Week 19:
• Week 20: 300 g and 19 cm.

Hair begin to grow. The foetal eyes are still shut even as little eyelashes appear. Fingerprints are formed. Fluttering or stirring may now be felt from the growing foetal body movements. These are all important signs in a pregnancy, so make a special note of this day.

• Week 21: 20 cm;
• Week 22: 460 g;
• Week 23:
• Week 24: 600 g and 23 cm;

Muscle and nerve connections begin forming. A layer of fat gets deposited under a red wrinkled skin and most of the foetal weight is gained; maturation begins, and with it, early breathing practices and the experience of touch. The foetus can now hear music and words spoken outside.

• Week 25: 24 cm;
• Week 26: 820 g;
• Week 27:
• Week 28: 1100 g and 27 cm;

Lungs take their first breath. Eyelids slowly open revealing the eyes. A cycle of sleeping and waking begins. A heartbeat now is clearly heard with a stethoscope. Foetus can now experience taste as its papillae are fully formed. Its skin is now covered by vernix.

• Week 29: 28 cm;
• Week 30: 1300 g;
• Week 31:
• Week 32: 1800 g and 30 cm;

Hair on the head grows longer. The foetus begins to focus its vision as its eyebrows and eyelashes become fully developed. Active breathing. Lanugo disappears from the face and the soft skin becomes a little less wrinkled as a layer of fat thickens.

• Week 33: 31 cm;
• Week 34: 2100 g;
• Week 35:
• Week 36: 2200 g and 34 cm;

The foetus adopts the shape of a ababy with its head now proportionate to its body. Eye focus and blink and become light sensitive. Organ system are now working. Fingernails are fully formed as lanugo disappears from the body and ear cartilages soften. Well-shaped contours are now apparent as a result of the layer of subcutaneous fat.

• Week 37: 35 cm;
• Week 38: 2900 g;
• Week 39:
• Week 40: 3200 g and 36 cm;

During the last two months of the pregnancy, fifthy-percent of the baby’s full term weight will be reached. The head is now firm and has the largest circumference of all body parts. The vernix will now disappear from the skin.