Pregnancy at 6 Weeks
In certain cases where it is necessary to confirm a pregnancy very early on, an ultrasound scan may be given, but it may not be able to detect the embryo at less than 8 weeks. Alternatively, you may be offered a trans-vaginal ultrasound scan -where a probe is placed into the vagina. This may just be able to show the 'flickering' of your baby's heart at 6 weeks of pregnancy.
Babies, up to 14 weeks, are measured in terms of crown to rump length, that is from the top of the head to the end of the bottom, measured as if they were sitting down. This measurement can be used to determine how many weeks pregnant you are and so give you an estimated delivery date (EDD). These scans are most accurate when they are done at around 10 weeks because there is more variation in fetus size later in pregnancy.
Development in 6th Week Pregnancy
Your baby's embryonic heart is now beating, but it only has two chambers (not four), because the circulation is not yet completely developed. The most advanced system at this stage is the central nervous system: the neural tube has now closed over and the brain is developing at one end. The liver beg to develop before the rest of the digestive system.
Your developing baby now resembles a tiny seahorse. This is because the tissue at the tail end grows faster than that at the front end, giving this distinctive shape. She is floating in a bubble of fluid, which will eventually develop into the amniotic sac. At this stage it is known as the yolk sac, and it provides your baby with oxygen and nutrients until the placenta is fully formed.
The large head seems out of proportion to the body, but the growth of the brain and head is particularly rapid at this early stage of development. Limb buds have appeared and, at the base of the head, there are folds that will develop into facial features, such as the eyes and ears.