pregnancy week by week

your forty-week
story, made clear.

Choose your pregnancy week for a direct answer on what is developing, what you may notice, what deserves attention, and what you and your partner can do next.

First trimester

week1Pregnancy is counted from your last period — there is no baby yet this week. Your body i…week2Around the middle of this week, ovulation releases an egg ready for fertilization — the …week3A cluster of cells (the morula and then blastocyst) is drifting through the fallopian tu…week4Your baby is the size of a poppy seed. The embryo is implanting and forming three cell l…week5Tiny but mighty — your baby's tube-like heart is beating for the first time, even though…week6The embryo curls into a tiny crescent. Eyes, ears, and limb buds start sketching themsel…week7Limb buds lengthen into paddles. The brain divides into three primary regions and the um…week8Officially a fetus now — fingers and toes start to separate, and tiny movements begin.…week9All essential organs are present in primitive form. The face becomes more recognizable a…week10The fetus can flex tiny limbs, swallow amniotic fluid, and kick — though you can't feel …week11Hair follicles, fingernails, and tooth buds are forming. Hands and feet are no longer we…week12End of the first trimester. Reflexes are kicking in — if you poke your belly, the baby w…week13Welcome to the second trimester. Your baby has unique fingerprints and can already make …

Second trimester

week14Tiny eyebrows and a fine layer of fuzzy hair (lanugo) start appearing. The baby can squi…week15The baby can hear muffled sounds now — your voice, heartbeat, and digestion. Bones are g…week16The baby is growing fast — facial features fall into place, and tiny ears move closer to…week17A waxy coating called vernix starts to protect the skin. Sweat glands form, and the umbi…week18The baby is twisting, stretching, and yawning. The reproductive system is fully formed a…week19Halfway through pregnancy is around the corner. Tiny taste buds work, and the baby can r…week20Halfway there. Many people are offered an anatomy ultrasound this week to check on your …week21Now measured head-to-heel, your baby is the length of a carrot. They can swallow amnioti…week22Your baby's senses sharpen. Lips, eyelids, and eyebrows are fully formed and tiny tooth …week23Skin is still wrinkly because there's not much fat yet. But your baby is gaining weight …week24A major milestone — the baby reaches the 'viability threshold'. With intensive medical c…week25Hair is growing in real color and texture. Your baby's hands work now — they grasp and r…week26Eyes open for the first time this week. The baby can see only dim shadows but reacts to …week27Welcome to the third trimester. The brain is more active than ever, and the baby is slee…

Third trimester

week28Your baby weighs about a kilogram now. They blink, dream, and respond to your voice with…week29Rapid weight gain begins. The baby fills out and starts to look more like a newborn each…week30Lanugo (fine body hair) starts shedding. The baby's brain develops folds and grooves for…week31Your baby's senses are nearly newborn-ready. They can hear, see, taste, and respond to t…week32The baby practices breathing motions — pulling amniotic fluid in and out. Lungs are near…week33Your baby's immune system is borrowing antibodies from you, building defenses for life o…week34Most of the time the baby's eyes are open while awake and closed while asleep. Lungs are…week35Brain growth is rapid — adding billions of new connections every week. Your baby is fini…week36Your baby drops lower into the pelvis. This 'lightening' frees up breathing but brings m…week37Officially early term. Your baby is fully developed and could arrive any day — though mo…week38All systems are go — the baby is ready for birth and just adding final touches of fat an…week39Full term. Your baby is fully developed and ready to meet you any day now.…week40Your official due date is here. Only 1 in 20 babies arrive on it exactly — most come wit…