As early as 5 weeks, exciting things are happening in your pregnancy. The mass of cells making up the embryo now begins to form a distinct shape, and body systems begin to develop. If you haven't already, you may begin to have nausea.
Size
By now, the baby is about 1/17 of an inch long. That's approximately the size of a pen tip.
Heartbeat
The first functioning organ system, the circulatory system, takes shape this week. Blood circulation begins and the baby now has a heartbeat that can be detected by ultrasound.
Placenta
The placenta develops during this week. It is through the placenta that the baby receives nourishment from the mother.
Spinal Cord And Brain
During this week, the baby's brain and spinal cord begin to develop. The neural tube, which eventually evolves into the spinal cord and brain, now runs the entire length of the embryo.
Eating
Some foods can cause illnesses such as toxoplasmosis and listeriosis, which can cause miscarriage or birth defects. You should not eat foods such as soft cheeses, unpasteurized milk and juices, raw eggs or foods containing raw eggs, raw or undercooked meats, raw shellfish and pate.
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