Some women are 12 weeks pregnant and barely notice, while others are well aware of the changes happening to their body.
You can expect to have your 'booking' visit at your local maternity unit (so-called because in days gone by you used to have to 'book' a bed to give birth in) between weeks 10 and 12 and a dating scan.
This is exciting as is the first glimpse of your unborn baby and you will also be given an estimated due date. In a regular healthy pregnancy, if you're expecting your first child, you're likely to have up to 10 antenatal appointments in all. If it's a subsequent pregnancy, you will be offered around seven.
Inside story
The embryo is measured from 'crown to rump', which means from the top of the head to the bottom of the spine, and you'll see this recorded on your maternity notes (which you'll pick up at your booking appointment) as 'CRL' for crown-rump length.
• At 7 weeks your baby is just 9mm long – but that's a lot of progress from being a mere speck at conception! As well as continuing to develop features like limb buds (the sprouting stage of arms and legs) your baby is starting to move around, but there's so much available space in your amniotic sac that you won't feel anything yet.
• At 8 weeks your baby (or 'fetus' - no longer an embryo by definition) is about 2.2cm long. The umbilical cord is formed and your baby's mouth is able to open and close.
• By week 9 fingers and toes are developing and although the fingers are a bit webbed your baby will have unique fingerprints already. Sex organs are taking shape, although you will have to wait until your 20-week scan if you wish to discover the sex. Some hospitals and PCTs have a policy of not divulging a baby's gender for ethical reasons.
• By week 10 your baby will have developed all the major organs and will have the ability to grab the umbilical cord.
• During week 11 lips, eyelids and genitals are fully formed and your baby measures about 4cm from crown to rump. The average baby weight at 11 weeks is 7g, which is just over a quarter of an ounce. Your baby can suck, swallow, kick and punch by this stage.
• Sadly one in four women experiences a miscarriage during these early weeks. If you miscarry, seek advice and support to come to terms with your loss.
On the outside
You can expect plenty of physical changes even before you're 12 weeks pregnant. Here's a rundown:
• Hang on, can you smell something? Chances are your nose will have gone into overdrive and you'll be hyper sensitive to smells. Common culprits bugging mums-to-be are cigarette smoke, burger bars and frying bacon as well as favourite perfumes, coffee and curry, all of which could bring on a bout of nausea. Your sense of taste goes hand-in-hand with your sense of smell, so certain foods start to taste a bit funny. Many expectant mums say they have a metallic taste in their mouths – in fact, this can be another early sign of pregnancy.
• It's common to feel nauseous and prone to sickness during early pregnancy. This can happen at any time of the day, which is why it's referred to as 'pregnancy sickness' rather than 'morning sickness' these days. Some women suffer throughout pregnancy, although this is thankfully rare – and some get 'hypermesis gravidarum' (HG), which is severe vomiting that requires medical treatment or even hospitalisation. This is even rarer with around 2% of women suffering from it. The good news is that normal pregnancy sickness is thought by medical professionals to be a sign that a pregnancy is well established.
• Being pregnant is hard work so it's hardly surprising most expectant mums find themselves feeling physically drained and in need of plenty of sleep in the first three months when all the big developments are going on.
• Nosebleeds and dizziness are common due to the increase in blood that's necessary to sustain you and your baby.
• Your breasts could be growing: that's one of the pluses of pregnancy for many women. Make sure to get measured regularly and get a good, supportive, non-wired bra whenever you go up a size. That way you'll feel a whole lot comfier than squeezing yourself into tight lingerie.