The baby still looks like a tadpole as a tiny tail (extension of the tailbone) is still there; but, it is retrieving fast and will disappear within a few weeks .
Sensory organs and facial development: The lens and retina attaches themselves as the eyes develop. The jaw, mouth, lips, teeth, tongue  and the tip of the nose also begin developing at this stage while tiny veins start to grow beneath the thin skin layers . The inner ears continue their development from the previous week.
Internal organ and system development: This is also the week when the liver begins producing red blood cells until the bone marrow is mature enough to take over the job. The appendix and pancreas begins to form, which will later produce insulin hormone to help in digestion. A part of the growing intestine connects to the umbilical cord for carrying oxygen and nutrients through the blood vessels in the area . The sex glands also start to form; however, it is still too early to see whether it is a boy or girl on an ultrasound picture . The kidneys are already in place and will soon begin to produce urine which will form a significant portion of amniotic fluid.
Growth of the arms and the legs: The limb buds start to flatten and form cartilage (which will later turn into bones) , preparing to grow the hands, foot, fingers and toes. The elbows start to develop with the lengthening of the limb buds or arms .
Nervous System Development: Your baby’s nervous system continues to grow  as about 100 nerve cells are developing every minute . The forebrain divides into two parts which will later form the cerebral hemispheres 
At the seventh week of growth, the embryo is about 1.25 cm long (crown-rump length)  – almost as big as a cherry .
Most women are likely to gain some weight by this time while those suffering from severe morning sickness may even lose some weight. Your clothes may start getting a bit tight , especially around the waist. Although, it is too early to start wearing maternity clothes, you may pick some loose clothing to stay comfortable. Fuller legs and breasts are other body changes occurring during the seventh week (the breasts become larger as the body prepares to produce breast-milk for the future baby) 
Another major change occurring during this period is the formation of the mucus plug in the cervical canal opening to keep the uterus safely sealed. This mucus plug automatically dissolves when you approach labor and childbirth 
A pelvic exam will show an increased size of the uterus  but, the baby is still too small for you to start showing. However, some women may have increased belly size due to extreme bloating.
Ultrasound scan performed during this stage shows two black dots partially covered by folds of eyelids, which will later form the baby’s eyes . Your doctor may be able to hear and see the heartbeat on an ultrasound and show it to you as well .
You may be asked to have another test in a week in case of irregular or no heartbeat. Ultrasound pictures also show the head to be disproportionately larger compared to the body due to the rapid brain development .
Most women continue to experience the common early pregnancy symptoms while it is also normal to have few or no symptoms . The emotional symptoms (depression and mood swings) may worsen during this week. The symptoms of nausea and vomiting (morning sickness), heartburn, gas, menstrual-like mild abdominal cramping, diarrhea/constipation (due to high progesterone levels), queasiness , food aversions or cravings, headache, dizziness and lower back pain may be accompanied by:
The symptom of morning sickness is likely to be comparatively severe in women carrying twins due to higher pregnancy hormone levels.
Published on November 29th 2013 by Pregmed Editorial Team.
Article was last reviewed on 13th August 2014.