Fetal development week by week
Follow your baby's development from a tiny mass of cells through to a fully developed baby. Our medical illustrations show how your baby is growing inside your uterus, while our Inside pregnancy videos take a 3D animated look at a baby from conception to labour and birth.
Click on your specific week to get a detailed description of how your baby is developing, or see the whole nine months in one timeline!
See what happens inside you during the conception process.
Your baby is an embryo consisting of two layers of cells from which all her organs and body parts will develop.
Your baby is now about the size of a kidney bean and is constantly moving. He has distinct, slightly webbed fingers.
By now your baby is around 7cm to 8cm (3in) long and weighs about the same as half a banana. Her tiny, unique fingerprints are now in place.
Your baby is now about 13cm (5.5in) long and weighs 140g (5oz). His skeleton is starting to harden from rubbery cartilage to bone.
Eyebrows and eyelids are now in place. Your baby would now be more than 27cm (10.5in) long if you stretched out her legs.
Your baby weighs about 660g (1.5lb). His wrinkled skin is starting to smooth out as he puts on baby fat.
By now, your baby is more than 40cm (15in) long. She can open and close her eyes and probably see what's around her.
Your baby now weighs about 2.2kg (4.7lb). His layers of fat are filling him out, making him rounder, and his lungs are well developed.
Your baby is almost due. At birth, the average baby is about 51cm (20.5in) long from head to toe and weighs an average of 2.9kg (6.4lb), but babies vary widely in size at this stage.
See our summary of how your baby is developing from two months. Within each month, 3D ultrasound images give you an idea of how your baby may look.
Click on your specific week to get a detailed description of how your baby is developing, or see the whole nine months in one timeline!
Conception
One month pregnant
Two months pregnant
Three months pregnant
Four months pregnant
Five months pregnant
Six months pregnant
Seven months pregnant
Eight months pregnant
Nine months pregnant
Month by month with ultrasound images
Track your baby’s development
Join now to receive free weekly newsletters tracking your baby’s development and yours throughout your pregnancy.
By registering you agree to our Terms of Use & Privacy policy. We use your information to send you emails, product samples, and promotions on this website and other properties. We use your health information to make our site even more helpful.
