By seven weeks, the embryo has grown to about 10mm long from head to bottom. This measurement is called the "crown-rump length". The brain is growing rapidly and this results in the head growing faster than the rest of the body.
The embryo has a large forehead, and the eyes and ears continue to develop. The inner ear starts to develop, but the outer ear on the side of the head won't appear for a couple more weeks.
The limb buds start to form cartilage, which will develop into the bones of the legs and arms. The arm buds get longer and the ends flatten out – these will become the hands.
Nerve cells continue to multiply and develop as the nervous system (the brain and spinal cord) starts to take shape.
Conception usually takes place about two weeks after your last period, around the time that you ovulate (release an egg). In the first four weeks of pregnancy you probably won’t notice any symptoms. The first thing most women notice is that their period doesn't arrive. Find out about the signs and symptoms of pregnancy.
By the time you are eight weeks pregnant, you will probably have missed your second period. However, some women experience a little bleeding during the early weeks of pregnancy. Always mention any bleeding in pregnancy to your midwife or GP, particularly if it continues and you get stomach pain.
Your womb has grown to the size of a lemon by the time you are around seven or eight weeks pregnant. You're probably feeling tired. Your breasts might feel sore and enlarged, and you are probably needing to pass urine more often than usual.
Some pregnant women start to feel sick or tired, or have other minor physical problems for a few weeks around this time. Most women stop having morning sickness and start to feel better by the time they are around 14 weeks pregnant.