You and your baby at 0-8 weeks pregnant
Three weeks after the first day of your last menstrual period, your fertilised egg moves slowly along the fallopian tube towards the womb. The egg begins as one single cell. Early on this cell divides again and again. By the time the egg reaches the womb, it has become a mass of more than 100 cells called an embryo, and is still growing. Once in the womb, the embryo burrows into the womb lining. This is called implantation.
In weeks four to five of pregnancy, the embryo settles into the womb lining. The outer cells reach out like roots to link with the mother’s blood supply. The inner cells form into two and then later into three layers. Each of these layers will grow to be different parts of the baby’s body. One layer becomes the lungs, stomach and gut. Another becomes the heart, blood, muscles and bones.
The fifth week of pregnancy is the time of the first missed period, when most women are only just beginning to think they may be pregnant. Yet already the baby’s nervous system is starting to develop. A groove forms in the top layer of cells. The cells fold up and around to make a hollow tube called the neural tube. This will become the baby’s brain and spinal cord, so the tube has a "head end" and a "tail end". Defects in this tube are the cause of spina bifida.
At the same time, the heart is forming and the baby already has some of its own blood vessels. A string of these blood vessels connects the baby and mother and will become the umbilical cord.
By the time you are six to seven weeks pregnant, there is a large bulge where the heart is and a bump for the head because the brain is developing. The heart begins to beat and can be seen beating on an ultrasound scan. Dimples on the side of the head will become the ears, and there are thickenings where the eyes will be. On the body, bumps are forming that will become muscles and bones, and small swellings called limb buds show where the arms and legs are growing. At seven weeks, the embryo has grown to about 10mm long from head to bottom. This measurement is called the "crown-rump length".
Your pregnancy is dated from the first day of your last period, although conception usually takes place about two weeks after that, 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, although a little bleeding occasionally occurs around the time you are six, seven or eight weeks pregnant. 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 an apple by the time you are around seven or eight weeks pregnant. You’re probably feeling exhausted. Your breasts might feel sore and enlarged, and you are probably needing to urinate 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.
Things to think about
Finding out you’re pregnant
The most reliable way of finding out if you’re pregnant is to take a pregnancy test. Once you think you could be pregnant, it’s important to get in touch with a midwife or doctor to confirm this and start your antenatal (pregnancy) care.
Help and advice for teenagers
Discovering you’re pregnant can be tough, but there is help out there.
Common pregnancy problems
From morning sickness to vaginal bleeding, find out how to cope with the minor and more serious symptoms that can occur in pregnancy.
Your feelings and relationships
Pregnancy is a time of physical and emotional changes that can affect your relationships, so get as much information and advice as you can to help you cope.
The best way to make sure both you and your baby stay healthy is to make sure you get all the care available to you during pregnancy. This includes scans and checks, screening, and free dental care.
Infections that may affect your baby
Some infections you may catch or carry, such as chickenpox or rubella, can affect your baby’s health, so it’s important to get yourself checked if you think you may be at risk.
You can save a to-do list online to keep track of your pregnancy essentials, such as taking folic acid and getting free dental care.
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