6 weeks pregnant
Pregnancy begins when your egg is fertilised in the fallopian tube and forms a rapidly dividing ball of cells, which travels to the uterus.
It burrows into the uterus (called implantation) and while the inner layer of cells develops into an embryo, the outer layer becomes the placenta. The placenta supports your pregnancy by delivering oxygen and nutrients from you to your growing baby.
A bit of embryology
Your embryo starts as a flat disc that develops three layers of cells. These are called the ectoderm, mesoderm and endoderm. This may be more information than you need but what your baby does with these layers is deeply impressive. She grows specific parts of her body from each layer:
- The ectoderm layer develops into the brain, nervous system, hair, nails, enamel in teeth, sweat glands and the linings of the ear, nose, throat and eye (parts of the body that come into contact with the outside world - smelling it, seeing it, eating it).
- The mesoderm layer develops into your baby's head and its muscles, bone, heart, arteries, veins and kidneys. It is the layer that supports the body.
- The endoderm develops into the lining of the body, such as the cells lining the gut, lungs and bladder.
Your baby at six weeks
- At six weeks she has buds shaped like paddles that become arms and legs. Grooves develop in the paddles that will grow into fingers and toes.
- She'll have a big head with a bump that's her developing brain and little outgrowths that will become ears.
- Her nervous system is developing from a neural plate - a layer of cells you can see on the 16th day of development that forms a groove down the middle. The edges of the groove curl up and meet to make the neural tube. The front bit of tube becomes the brain; the rest grows into the spinal cord. The neural tube becomes a closed tube at six weeks. If it doesn't close the baby develops a neural tube defect (spina bifida), which means there's an opening when there shouldn't be. Folic acid protects your baby against neural tube defects and also from cleft palate (where the roof of the mouth does not fuse together).
- Little darker areas for your baby's nose and eyes are also appearing.
- Your baby's heart is already dividing into chambers (hearts have a right and left side, and upper and lower chambers) It is beating and, as your baby's blood vessels continue to grow round the body, it starts pushing blood through these new blood vessels.
- Her lungs are beginning to develop.
- She's starting to grow muscles and during the sixth week can twitch her body and arms. The legs develop a little after the arms do.
- She knew she was a girl, or he knew he was a boy, as soon as the egg and sperm fused, depending on whether the sperm has an X or Y chromosome.
Your baby's size
Considering all these achievements, it's incredible to think how tiny your baby is. From the top of the head to the middle of her buttocks - what doctors call the crown-rump length - your baby will be a tiny 10-14mm tall: the size of a small bean.
Your baby will be surrounded by a sack called the amniotic sac, full of fluid to cushion it and keep it safe.
She will be joined to you, her mum, through the umbilical cord, which will do the job of sending in food and taking out the waste products.
How your body is changing at six weeks pregnant
Some women feel the effects of being pregnant quite dramatically. Others feel a bit nauseous and wonder what all the fuss is about. It's a very individual thing, determined partly by your response to the increase in hormones. But you can expect to have some degree of:
- Morning sickness Morning sickness happens any time and can vary from mild nausea to vomiting at will. For some women smells, such as a whiff of cigarette smoke, can trigger it. Eating little and often, avoiding fatty foods, eating ginger biscuits... there are all sorts of tactics that can help morning sickness.
- Tiredness Pregnancy tiredness can be overwhelming and spread from your ankles up through your body. It can make you thankful you're pregnant because otherwise you'd think you were dying.
- Tender breasts They may have been tender when you had your period but pregnancy takes them into another dimension. The merest brush against them can make you scream. But they will be bigger, which for some of us is some comfort. In fact, this is the window of opportunity where your breasts may be larger than usual and your stomach isn't - so enjoy it.
Nutritional supplements to take during pregnancy
You should take 400mcg of folic acid a day, a nutritional supplement that reduces the risk of your baby having spina bifida.
Latest NICE guidance says women may choose to take 10mcg of vitamin D. Vitamin D is essential for absorbing calcium (needed for healthy bones- yours and your baby's) and some women may not get enough in their diet.
Don't take other nutritional supplements without asking your midwife or GP.
You don't necessarily need to take iron and you should avoid vitamin A (there is a lot in liver so avoid it, especially in pate because then you can catch listeria too) because it can cause your baby to develop abnormally.
Foods to avoid during pregnancy
The list of foods to avoid in pregnancy often changes – so you should ask your midwife for advice. Two of the main concerns are listeria, a bacteria that can cause miscarriage or stillbirth, and salmonella, a bacteria that can give you sickness and diarrhoea.
- Listeria Avoid mould-ripened cheese such as brie, camembert, stilton and other blue-vein cheeses, pâté, uncooked meat (so no Steak Tartare) and unpasteurised dairy produce need to come off the menu. Shellfish and raw fish should also be resisted. Listeria can be found in soil and mud so you should ask your midwife what the latest views are about gardening or mud wrestling in pregnancy.
- Salmonella Avoid partially cooked food (especially poultry) and steer clear of raw, partially cooked eggs and any food made from them such as mayonnaise.
- Toxoplasmosis You can avoid toxoplasmosis, a parasite infection that can harm your baby's sight, hearing and brain, by making sure you thoroughly cook meat and poultry.
Drinking and drugs during pregnancy
It's during the first eight weeks that your baby is most sensitive to any harmful effects from drugs and alcohol. NICE guidance says you should not drink at all in the first three months.
As soon as you think you might be pregnant you should look at any drugs you are taking - prescription or recreational - and tell your doctor.
The reality is many women don't realise they're pregnant and carry on drinking and smoking through the first few weeks of their baby's development. As long as you stop as soon as you realise, then it's extremely unlikely your baby will be affected. Babies seem to be remarkably robust.
Illustrations taken from The Pregnancy Encyclopedia, £25, published by DK.
Disclaimer: The information in the pregnancy calendar is for general information and is not intended as a substitute for the medical advice of your own doctor or antenatal team. Not all babies develop at the same time and in the same way, so this week-by-week guide may not always match your own experience. If you have any worries, consult your antenatal team or GP.
Last updated: 11 days ago