Your week by week guide on what to expect when you're expecting...

12 – 16 Weeks Pregnant

When you are 12 Weeks Pregnant your baby will weigh around 14 g and will be about 5.5cm long.  Their skeleton is now complete and their bones are beginning to harden.  They will be moving very frequently although you will not be able to feel this yet.

When you are 13 weeks pregnant your baby will weigh about 20 g and will be about 6cm long from the top of their head to their bottom , the size of a big Prawn!  He or she will be able to move his hands and even suck their thumb.

By week 14 they will be about 8cm long and weigh about 40g and will be growing a fine layer of protective hair called lanugo.

By week 15 they will weigh about 70 g and will be about 9cm long. They will be starting to grow eyebrows and head hair.

By 16 weeks they will be about 10cm long from head to bottom and will weigh about 100g. Their heart is pumping nearly 30 litres of blood a day.


Do you Show yet?

You may be starting to grow a small bump – this perhaps will only be noticeable to yourself or your partner or those very close to you.  If you do not yet have a bump, you may be wondering when your pregnancy will start to show!

How quickly you develop a bump can depend on your body shape, your height and the length of your torso (Women with a relatively shorter torso will normally begin to show earlier as there is literally less room for the baby to go as it grows).  If you are having a second baby, it is likely that you will show sooner. Sometimes skinny women show earlier than others, and sometimes they do not show until 6 months or so, it literally depends on the shape of your body and how it adapts to a baby growing inside you.

You may start to notice a widening of the hips and some general weight gain which can be a little disheartening especially if there is no bump to speak of yet!  You may just feel fat and not particularly pregnant.

Braxton Hicks

Your Uterus contracts all the time (in the same way that your heart does) but you will be unaware of this when you are not pregnant.  When you are pregnant however, you may become aware of these tightenings or contractions (known as Braxton Hicks) from around 16 weeks.   Most women may not notice them until they are towards the end of their second or third trimester when the uterus is much larger.  Some women will not notice them at all.  For most women these are totally painless and have no clinical importance. But as the pregnancy progresses they can become uncomfortable and even take your breath away.  BH contractions are random and there is no rhythmic pattern to them- they are not associated with show of blood or any other worrying signs.   Many women do not start to feel them until late stages in their pregnancy or even in the few days before labour begins, and some claim never to experience them at all. Many women experience them without even feeling them and are thus unaware that they ever had them.  These tightening feelings can be quite surprising or alarming when they first start but they are perfectly normal and many women experience in abundance them right up until birth.  They do not indicate anything serious, nor do they mean you will go into labour earlier than someone who does not feel them. You may become more aware of these in successive pregnancies.


Heartburn is a common complaint for many women as their pregnancy progresses. The hormone progesterone relaxes the uterus and other muscles, including those around the sphincter of the stomach , which can allow acid contents of the stomach to escape back upwards causing heart burn. 

Later on in pregnancy this will be aggravated by the physical presence of the baby who is causing the stomach to be pushed up.  In the same way, increased progesterone can also cause constipation, as the smooth muscles in the bowel relax and are no longer contracting as much, reducing gut motility, meaning transit times of food in your stomach are increased.  As a consequence, you will not be opening your bowels as often and stools may become harder.

Eating small amounts often rather than big meals can help with the heartburn.  Avoiding spicy foods can also help, although you may have gone off these anyway! 

If heartburn is affecting you then your saviour for the next few months will be Gaviscon or Gaviscon Advance.  Both these preparations are perfectly safe for you to take during your pregnancy and actually have the beneficial effect of helping to keep your bowels regular.  (Gaviscon acts as a mild laxative).  Your GP can prescribe Gaviscon for you in 500 ml bottles which you will be able to get for free if you have applied for your Maternity exemption certificate.  (Your GP or Midwife should give you a form which you can send off- this will allow you to pick up any prescriptions free of charge whilst you are pregnant and for one year after the baby’s birth! DO IT!!!)

This is really worth doing as a 500ml bottle normally costs about £8.00-£10.00 and if your heartburn is severe or continuous you will go through a lot of these!  But don’t forget – read the label and follow the dosage instructions.

Another tip to deal with indigestion is to make sure you stay upright after eating.  Slouching on the sofa will not help your digestion, so staying seated at the dining table or even sitting on a yoga/exercise ball after your meal can help.  This can be especially beneficial in the last few weeks of pregnancy when sitting on the sofa may become more uncomfortable and a Yoga Ball may be the only comfortable place to sit!  


Your nausea should have passed by this stage unless you are really unlucky in which case it could continue to 20 weeks and for some women it can even last for the whole of the pregnancy.

In most cases you will be feeling good and pretty normal. 

You may be feeling what many women would describe as “hormonal”- moody, irritable, easily upset or reduced to tears.  This is very normal and is a result of the extra hormones whizzing around your body. Combined with increasing fears about the future, the impending birth and how you will cope as a mother can all contribute to a feeling of unease or anxiousness. It can help if you explain these feelings and the reasons behind them to your partner or those around you so they understand that your personality change is not going to be permanent and perhaps go easy on you!

Feeling the Baby Move

You may start to feel baby move in the form of flutters, bubbles or movements in your stomach that you have not felt before.  At the beginning you may be unsure as to what feelings are wind and what are really the baby, but as time goes on you will begin to differentiate the baby’s movements from your bowels.  If this is your first baby you may not start to feel it move until closer to 20 weeks, but if this is your second or third, you may start to feel it earlier.

When to Book an Antenatal Class

If you want to do “in-person” classes in your area then do look into this sooner rather than later as they can get booked up quickly.  

The cost of antenatal courses can vary greatly (from £100 to £400) depending on the qualifications of your teacher, what area you live in and how long the course is (2 full days or hourly sessions every week).

But, if you can’t afford a local class, or are just too busy to make it because of other commitments, then we offer Online Antenatal Courses you can take in the comfort of your own home!

Antenatal courses can be invaluable for not only learning about your pregnancy and the all important birth, but also for  meeting new mothers in your area.  There is the odd complaint that some antenatal class teachers can lack impartiality on certain subjects such as breast versus bottle feeding, so it can help to talk to people in your local area to find out more about the course before you sign up.  You do not want to be made to feel uncomfortable about choices you want to take about your birth or the feeding of your child.

Read about the next stage, 16 – 20 weeks

there's more to explore...

Want to know what to expect week by week in pregnancy? Got some burning questions for what you can and can’t do with a bun in the oven? Want to find out what might happen during your labour… it’s all in our free guides! 

what to know what will happen in other weeks?

10% off

Get 10% off any of our courses & stay in the loop about snacks and stuff!