Newsletter from Essential baby - week 6

How big is my baby?

At the start of week 6 the length of your baby is no greater than 2-4mm (0.08 - 0.16 inches) from the top of it's head to it's rump. The crown-rump measurement, rather than the crown-toe measurement is used because your baby's legs bend up towards the body in utero, making it difficult to get an accurate crown-toe measurement.
How does the embryo develop this week?

Week 6 is a busy one, and marks the start of the embryonic period (weeks 6-10 of your pregnancy). During the embryonic period the basic foundations for your baby's life are set, so the embryo is sensitive to any negative factors (alcohol, nicotine, excess caffeine, chemicals and pollutants) that may hinder it's development. Check out the Hazards and Precautions section of the Essential Baby web site for more detailed information.
This week the embryo develops 2 cavities, the amniotic sac and the yolk sac. The amniotic sac continues to enlarge and gradually envelops the embryo and body stalk. The yolk sac never attains a large size and disappears as soon as the fetus begins to obtain nourishment from the placenta. The body stalk that connects the embryo to the developing placenta (trophoblast) gradually becomes elongated and develops into the umbilical cord, containing 2 arteries and a single vein.
By week 6 your baby's heart is prominent and beating. The next step is the development of your baby's owns unique blood vessels, and a blood supply that is completely separate to yours. Your baby's circulation first uses the resources of the yolk sac, then later the placenta. Its circulation is closed (covered by the trophoblastic covering) and does not mix directly with your blood. It is your blood that is open to the uterus and feeds the baby, so if placental separation occurs, your blood will be lost, and not the baby's.
By the middle of the week the neural tube closes at your baby's head, where it will form the early brain chambers. By the end of the week the tube has also closed at the bottom of your baby's back. The arm and leg buds are forming and various organs and other body systems are under way.
With all these physical changes, the embryo develops from a layered disc to adopt a C-shaped curvature, taking on a curved body form with a head and tail.
What pregnancy symptoms will I be experiencing?

This week you may start to develop other more noticeable signs of pregnancy, such as nausea possibly accompanied by vomiting (especially in the morning), breast soreness or tenderness, the need to urinate more frequently, fatigue, and constipation. Do not use laxatives without first talking to your doctor. Try to exercise, drink more fluids and eat foods that are high in fibre. Visit the Pregnancy Symptoms section of the Essential Baby web site for more details.