This guide to your pregnancy tells you how your baby is developing each month. It also tells you a bit about how your body may be changing and how you might be feeling. Remember that not all babies develop exactly like each other, so this can only be a general guide: you should ask your doctor or midwife for any specific information about your pregnancy. We all know that babies come in two flavours, however - as most of you won't know what flavour you're getting - for clarity we will refer to your baby as "she".

Remember to check out our Pregnancy discussion boards here for further advice on your pregnancy - from how to combat morning sickness to where to find the best maternity jeans, other Mumsnetters have it covered. Plus, join our online antenatal club and share your experience with other Mumsnetters due in the same month as you.

Your pregnancy at 6 to 8 weeks

Your pregnancy is counted from the first day of your last period. Strange as it may seem, when the sperm meets the egg you are already counted as being two weeks pregnant. So when your pregnancy test is positive you may well be 5 or 6 weeks through your total of 40 without realising. This is good news as time can stand still when you're pregnant - especially in the home straight. Your baby, however, starts sprinting to the finish line as soon as the sperm meets the egg. (Until your baby is 8 weeks old, doctors call it an embryo. We will call it a baby because embryo is too impersonal.) The first two months of her life are extremely busy. From between her 3rd to 8th week all of your baby's organs such as the heart, lungs and intestines will be developing. It is in this period that your baby is most sensitive to any harmful effects from drugs and alcohol. 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 that 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 (although occasional alcohol in moderation is not proven harmful) as soon as you realise then it's extremely unlikely that your baby will be affected. (See below for more things you should stop doing).

Your baby starts off as a flat disc of cells and not, as you might imagine a cute jellybean. These cells divide continuously and form three layers. 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. Your baby somehow manages to grow specific parts of her body from each layer. Each layer is programmed to do its job. You won't get any cells from the endoderm layer growing up to be part of your baby's bladder because they develop into the brain, nervous system, hair, nails, enamel in teeth, sweat glands and the linings of the ear, nose, throat and eye. Do any of these things have anything in common? The answer is yes: they are all parts of the body that come into contact with the outside world in some way - seeing, making sense of it, feeling it and, in the case of teeth, 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. While the endoderm develops into the lining of the body, such as the cells lining the gut, lungs and bladder.

The flat disc starts folding to form your baby's head and a temporary thin tail from around 4 weeks onwards. By the beginning of the fifth week, your baby will be developing buds shaped like paddles that will become arms and legs. By the 6th week these paddles will flatten at their ends and grooves appear in them, called rays. They appear in the hand first and then the feet and will grow into fingers and toes.

At 6 weeks, your baby will look a bit top heavy - her head will be disproportionately bigger because it is growing so fast but the rest will catch up later. To the side of the head she will start to develop little outgrowths (some medical textbooks call them hillocks) that will develop into ears. Little darker areas for your baby's nose and eyes are also appearing.

Your baby's heart is developing and dividing into chambers (the developed heart has 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.

Your baby is also starting to develop muscles and during the 6th week can twitch her body and arms. The legs develop a little after the arms do.

Considering all these achievements, it is 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.

Foods to avoid

Unfortunately the list of other things you should avoid when pregnant grows and changes all the time - so you need to ask your midwife what the latest information is. Two of the main concerns are listeria, a bacteria that can cause miscarriage or stillbirth, and salmonella, a bacteria that can give newborn babies diarrhoea and meningitis. The National Institute for Clinical Excellence has guidelines for pregnant women. To avoid listeriosis you should not eat mould ripened cheese such as brie, camembert, stilton and other blue vein cheeses. Pate, any uncooked or undercooked meals and any unpasteurised diary produce also need to come off the menu. Generally, this means shellfish and raw fish are also not safe. In America pregnant women are also advised not to eat hot dogs or any meats from the deli-counter. Listeria can be found in soil and mud so you should ask your midwife what the latest views are about mud wrestling or gardening in pregnancy! You should certainly wash fruit and vegetables under the tap and get any mud off. To prevent Salmonella you need to avoid partially cooked food (especially poultry) and steer clear of raw or partially cooked eggs and any food made from them such as mayonnaise. 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.

Nutritional supplements to take

If you haven't started already, you should be taking folic acid, a nutritional supplement that reduces the risk of your baby having spina bifida. You need to take 400 micrograms a day. You shouldn't take other nutritional supplements without asking your midwife. You don't necessarily need to take iron and you should avoid Vitamin A (there is a lot in liver) because it can cause your baby to develop abnormally.

How are you changing?

Some women feel the effects of being pregnant quite dramatically. Others feel a bit nauseous and wonder what all the fuss is about. It is 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:

It 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.

Tiredness:

This 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.

Spotty face:

Rather than bloom with pregnancy you can feel like an adolescent as your face erupts with spots and blemishes. It's the hormones and will pass.

Faintness:

You don't have to be in a Victorian melodrama to faint when you're pregnant - it's quite common to at least feel dizzy and light headed. If you have to bend down don't get up too quickly. If you are travelling by public transport no one will offer you a seat (nor will they even as your stomach swells to the size of a watermelon) so you will have to ask for one. In fact, as public transport combines heat and standing for long periods and thereby is a risky area for the pregnant woman, it's advisable to walk, take a cab... or just have a lie down instead!

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 most 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.