Pregnancy week-by-week

Whether you like it or not, pregnancy is diverse. Not only are no two pregnancies alike (sorry, just because your sister didn’t have morning sickness doesn’t mean you won’t get it), they can also vary week-by-week and day-by-day.

You…

In the first trimester (weeks 0-12) you’ll probably notice that from when you found out you were pregnant to around six weeks you felt no different physically, although mentally you’ll probably have been coming to terms with being pregnant. At around six weeks, (sometimes before), many women start to feel very tired. Pregnancy tiredness can feel a lot like jet lag – many women report getting home from work and having to go straight to bed. Not exactly ideal, but at least it doesn’t last for the whole nine months. The tiredness is thought to be down to the increasing levels of pregnancy hormones in your system, and also to the gradual formation of the placenta, which is your baby’s life support system.

Morning sickness, or pregnancy sickness (since it can actually strike at any time and even last all day and night) might develop soon after your feelings of fatigue. Some women don’t suffer from morning sickness but unfortunately, most do. Again, it’s down to the rapidly rising pregnancy hormones. Another factor is your heightened sense of smell, which means that cigarette smoke or food with a strong aroma can make you sick. Usually morning sickness clears up by 12-15 weeks, though for some unlucky moms-to-be it lasts throughout pregnancy.

The second trimester (weeks 13-27) sees your bump begin to show. You’ll bloom: your early pregnancy symptoms should ease off and you’re not yet large enough for the late-pregnancy slow down. But prepare yourself for it: in the third trimester (weeks 28-40) your growing baby can make getting around difficult. Heartburn is common as he presses against your stomach, and you’ll find you can’t stray too far from the bathroom!

Your baby…

It isn’t just you going through intense changes – your baby is growing rapidly. In the first 12 weeks, he develops from a cluster of cells into a tiny fetus. His heart will start beating at around 22 days after conception. By the end of the fourth week he’s around 0.014 of an inch long. His arm and leg buds are starting to develop, along with his brain, spinal cord and nervous system. By week 12 he’s fully formed – he’ll spend the rest of your pregnancy growing bigger.

Your baby spends much of the second and third trimesters growing bigger and preparing for life outside the uterus. At week 20 you’re halfway there – and may have begun to feel his first tiny kicks. In the second trimester his senses develop – by week 18 he can hear your muffled voice from outside the uterus. His lungs are producing surfactant, a substance that enables them to inflate, and he practices breathing.

In the third trimester your baby’s eyes open (around week 28) and can detect light by around week 33. His bones are fully developed but are still fairly soft – now they’ll start to harden. His movements are stronger and he’s piling on those pounds! If it’s your first baby he’ll engage (descend into your pelvis ready for birth) by around week 36. He’s around seven pounds or more – and he’s almost ready to be born!

No day is like another in pregnancy. One day you’ll be feeling on top of the world about your new baby – the next you’ll be feeling down about having to leave your job! Some women bloom and radiate through their pregnancies; others sport greasy hair and pimples.

We’ve created weekly guides for the whole of your pregnancy so you’ll know a little about what to expect that week. Our week-by-week roundups are just a guide and your pregnancy may differ. We can guide you through what to expect but your pregnancy will still be completely unique to you. We hope you enjoy our weekly updates, and find them  useful!

For a look at which week you’re in, visit our week-by-week guides.

The information in this feature is intended for educational purposes only. If you have any concerns about your health, the health of your child or the health of someone you know, please consult with a doctor or other healthcare professional.