In week 7 of pregnancy the umbilical cord, the vital link between your baby and your placenta, is clearly visible starting near the site where your baby implanted in your uterus. The umbilical cord contains two arteries and one large vein. Nutrients and oxygen rich blood pass from your placenta to your baby by way of the single vein and then back to your placenta through the two arteries. lt takes about 30 seconds for a blood cell to make the entire trip.
When 7 weeks pregnant, your baby’s brain is becoming more complex. Cavities and passages necessary for circulation of spinal fluid have formed. Your baby’s growing skull is still transparent. If you were able to get a look at it under a magnifying glass, you might see the smooth surface of your baby’s tiny, developing brain.
You may feel dizzy or even faint if you stand for too long or you are in a crowd. Overwhelming tiredness can also be a problem now, so make sure you get plenty of rest. If you don't feel like making love at the moment don't worry; this is quite normal and you may find that your sex life is better than ever in the second trimester.
The unborn baby is now known as a fetus and is about 0.5 inch (1,3 cm) long. The nostrils, lips, tongue, and teeth are beginning to form and the arms and legs are growing. Lungs are beginning to develop and the intestines, spine, and brain are almost fully developed.