A typical pregnancy lasts for about 40 weeks – that’s 280 days from the first day of your last period to the date of baby’s arrival. Lots of changes are going to occur during this time – so it’s helpful to know what to expect.
Your pregnancy is divided into three stages or trimesters. Each trimester lasts for about three months and has its own physical and emotional changes.
First Trimester (Weeks 1-12)
During the very early stages of pregnancy you may not notice any changes at all – the first sign most women notice will be a ‘missed period’.
By the second month (8 weeks), at this stage you may have missed your second period. Your pregnancy hormones may start to kick-in and affect your emotions and pregnancy tests will detect a positive result.
Physically, you may be feeling tired, have sore breasts and, with a growing uterus pressing on your bladder, you may have to go the toilet more often. Morning sickness may be a problem and you’ll start to gradually gain weight.
By the end of the first trimester, if you have not yet seen a healthcare professional already, contact your doctor or midwife to start planning your antenatal care.
If you would like to find out more about the baby’s growth in the first trimester, see baby’s first trimester
Baby’s first trimester
Your fertilised egg travels along the fallopian tube and burrows into the lining of your uterus (womb). The pregnancy hormone hCG (human chorionic gonadotropin – the hormone detected in pregnancy tests) starts to be produced.
Small buds appear which begin to develop into limbs.
By week 10 the tiny heart is formed and beating fast. At 12 weeks your baby is a fully formed foetus and has all its organs, muscles and bones in place – but it’s still probably too early to feel any movements.
Second Trimester (13-28 Weeks)
Your baby is getting bigger now and you’ll start to look pregnant. Things may get a little bit easier as morning sickness usually settles down around weeks 13-14 and you may start to feel your baby’s movements (weeks 17-20).
Other changes will start to occur as your body responds to your growing baby. Hair may become thicker and shinier, a dark line may develop down the middle of your stomach and stretch marks may appear around weeks 22-24.
Trouble sleeping, tiredness, headaches, and aches and pains in your lower back are also all common problems at this stage. You may begin to feel hungrier than usual or have trouble with indigestion or heartburn as baby presses on your stomach. Remember to keep to a healthy diet and know what foods to avoid.
Water retention may cause your hands or feet to swell – make sure you discuss this with your doctor or midwife to exclude any other medical conditions that may be a contribution to the swelling.
By the end of baby’s second trimester they will be fully formed and weigh about 1 kg.
Your baby is fully formed.
They are about 8 cm long and starting to form downy hair (lanugo) over their body.
They have begun to grow hair, eyebrows and lashes. Their mouth can open and shut, and their eyes can move (although the eyelids are still closed).
Your baby’s ears will be fully developed and able to hear muffled sounds from the world outside your belly.
Week 24: They’ve developed a daily routine of sleeping and waking.
Week 28: Your baby weighs about 1 kg.
Third Trimester (Week 29+)
The final three months can leave you feeling tired and uncomfortable. You may start to feel breathless from all the extra weight you’re carrying around and your baby pushing against your lungs.
You may start noticing strong Braxton Hicks’ contractions from around week 34. These are a normal part of your uterus ‘practicing’ for labour – if they become painful and frequent you should contact your midwife or hospital.
By the end of baby’s third trimester they are ready to be born – so it’s a good idea to get as much rest as possible before your baby arrives!
Baby’s movements will be coordinated and strong and they may be in the ‘head down’ position getting ready for the birth if they are not in the ‘head down’ position by this stage it is ok as there is still time for them to turn. Their skin will look plumper and they are at the stage of developing a sucking reflex.
Their lungs are usually completely developed.
Your baby is fully developed and ready to face the outside world. Most full-term babies weigh around 3-4 kg and arrive between 38 and 42 weeks.
Always talk to your midwife or doctor about any problems you may be concerned about.