Pregnancy week by week
Discover how your baby grows and how your body changes in every week of pregnancy. Pregnancy lasts 40 weeks divided into three trimesters, and each week brings its own signs.
Weeks are counted from your last menstrual period, not from when you took a test or first noticed something. Not sure which week you're in? Use the calculator below.
Calculadora de semanas de embarazo
Introduce la fecha de tu última menstruación
First trimester
Pregnancy Week 1: How the Weeks Are Counted
Pregnancy week 1 starts on the first day of your last period. I'll explain how pregnancy weeks are counted and why there's no baby yet at this point.
Pregnancy Week 2: Ovulation and Your Fertile Days
In pregnancy week 2 you ovulate. I'll explain when your fertile days are and what happens in this stage before conception.
Pregnancy Week 3: Fertilisation and Implantation
In pregnancy week 3, fertilisation and implantation happen. I'll explain what goes on in your body and why the test can still be negative.
Pregnancy Week 4: Symptoms, Tests and Baby Size
Find out what happens in pregnancy week 4: when to take the test, the first symptoms, the baby's size and the signs that everything is going well.
Pregnancy Week 5: Symptoms, Tests and Baby Size
Everything that happens in pregnancy week 5: when to take the test (it's time!), the first symptoms, the baby's size and tips for this moment.
Pregnancy Week 6: Symptoms, Ultrasound and Baby Size
Everything that happens in pregnancy week 6: the most intense symptoms, when you can see the heartbeat on your first ultrasound and the baby's size.
Pregnancy week 7: symptoms, ultrasound and baby size
Everything that happens in pregnancy week 7: the heart beats strongly, symptoms at their peak and how big your baby is. A calm, detailed guide.
Pregnancy week 8: symptoms, ultrasound and baby size
Everything that happens in pregnancy week 8: your little one is now the size of a raspberry, fingers are taking shape and movements begin. A calm, detailed guide.
Pregnancy week 9: symptoms, ultrasound and baby size
Everything that happens in pregnancy week 9: your little one is now the size of an olive, eyelids are forming and you're entering month three. A calm, detailed guide.
Pregnancy week 10: symptoms, ultrasound and baby size
Everything that happens in pregnancy week 10: your baby is now the size of a strawberry, stops being an embryo and becomes a fetus. A calm, detailed guide.
Pregnancy week 11: symptoms, ultrasound and baby size
Everything that happens in pregnancy week 11: your baby is now the size of a fig, it's time for the nuchal scan, and nausea finally starts to ease.
Pregnancy week 12: symptoms, baby size and the end of the first trimester
Pregnancy week 12 closes the first trimester: your baby is around 6 cm, the size of a lime, nausea eases and the risk drops. Here's everything that's happening.
Pregnancy week 13: symptoms, baby size and tips
Everything that happens in pregnancy week 13: your baby is now the size of a peach, the second trimester begins, energy returns and nausea eases. Here's all the detail.
Second trimester
Pregnancy week 14: symptoms, baby size and tips
Everything that happens in pregnancy week 14: your baby is now the size of a lemon, grows fine lanugo hair and makes faces, while your second-trimester energy starts to show.
Pregnancy week 15: symptoms, baby size and tips
Everything that happens in pregnancy week 15: your baby is now the size of an apple, its skeleton is growing firmer, it can start to hear you and may even get hiccups, while your bump starts to show.
Pregnancy week 16: symptoms, baby size and tips
Everything that happens in pregnancy week 16: your baby is now the size of an avocado, can start to perceive light, hears you better every day, and their little heart is already pumping litres of blood a day.
Pregnancy week 17: symptoms, baby size and tips
Everything that happens in pregnancy week 17: your baby is now the size of a pear, starts to store fat, practises breathing and their skeleton keeps getting stronger.
Tools and calculators
Every week we explain your baby's development, the most common symptoms and practical tips. If you have any questions about your pregnancy, remember this content is for information only: always consult your doctor.