The Developmental Stages of A Baby During Pregnancy

  • First day of the mother's last menstrual period

    First day of the mother's last menstrual period
  • Week 1

    Week 1
    Ovum fertilised, cell division starts
    Conception and fertilization
    This week, the mother ovulated, conceived and the soon-to-be-baby has started on its miraculous transformation from single cell to baby boy or girl.
  • Week 3

    Week 3
    Placenta and embryo begin developing, zygote implants in uterine lining, blastocyst:
    The blastocyst that will develop into the baby has completed its six-day journey from the mother's fallopian tube to her uterus. Once there, it burrows into her uterine lining and implants — making that unbreakable connection to the mother that'll last the next eight months
  • Week 4

    Week 4
    The baby's organs will begin to develop and some will even begin to function. As a result, this is the time when she or he'll be most vulnerable to anything that might interfere with them development. Right now your baby is an embryo the size of a poppy seed, consisting of two layers: the epiblast and hypoblast, from which all of the organs and body parts will develop.
  • Week 5

    Week 5
    Deep in your uterus your embryo is growing at a furious pace. At this point, it's about the size of a sesame seed. It's made up of three layers — the ectoderm, the mesoderm, and the endoderm — which will later form all of organs and tissues
    The heart is forming.
  • Week 6

    Week 6
    The nose, mouth, and ears are beginning to take shape.
    Intestines are developing, and the bud of tissue that will give rise to lungs has appeared.
    The rest of the brain, muscles, and bones are forming.
    The baby is now about the size of a lentil.
  • Week 7

    Week 7
    The baby’s hands and feet are emerging from developing arms and legs.
    Translucent eyelid folds partially cover the baby's eyes
    The baby is about the size of a blueberry now.
  • Week 8

    Week 8
    The baby's hands and feet are developing webbed fingers and toes, eyelids almost cover eyes and breathing tubes extend from throat to the branches of the developing lungs.
    In the brain, nerve cells are branching out to connect with one another, forming primitive neural pathways.
    The external genitals still haven't developed enough to reveal the baby’s sex.
    The baby is now the size of a kidney bean .
  • Week 9

    Week 9
    The baby's placenta and amniotic sac now have developed, and ears and mouth are forming.
    Eyes are fully formed.
    The heart finishes dividing into four chambers, and the valves start to form.
    The baby is about the size of a grape.
    The mother has to have blood tests to assess maternal health and risk factors.
  • Week 10

    Week 10
    Vital organs — including kidneys, intestines, brain, and liver (now making red blood cells in place of the disappearing yolk sac) — are in place and starting to function, though they'll continue to develop throughout pregnancy.
    The tissues and organs in the body rapidly grow and mature
    tiny nails forming on fingers and toes (no more webbing) and peach-fuzz hair beginning to grow on tender skin
    The baby's now the size of a kumquat.
  • Week 11

    Week 11
    The hands will soon open and close into fists, tiny tooth buds are beginning to appear under gums, and some of the bones are beginning to harden.
    The baby is effortlessly kicking and stretching inside the mother.
    The baby's about the size of a fig.
  • Week 12

    Week 12
    The baby can now reflex to things.
    The baby's fingers will soon begin to open and close, toes will curl, eye muscles will clench, and mouth will make sucking movements.
    His or her eyes have moved from the sides to the front of their head, and ears are right where they should be. The baby's face looks unquestionably human now.
    First ultrasound at 12 weeks.Tests for down syndrome, brain and spinal cord defects, chromosome abnormalities and major disabilities.
  • Week 13

    Week 13
    The baby's tiny fingertips have fingerprints, their veins and organs are clearly visible through still-thin skin, and their body is starting to catch up with their head — which makes up just a third of the body size now.
    If you're having a girl, she now has more than 2 million eggs in her ovaries.
    Your baby's length is about the size of a (pea pod) and weighs nearly an ounce.
  • Week 14

    Week 14
    Your baby can now squint, frown, grimace, pee, and possibly suck his thumb.
    From head to bottom, the baby is about the size of a lemon.
    The baby's body is growing faster than their head, which now sits upon a more distinct neck.
    By the end of this week, arms will have grown to a length that's in proportion to the rest of the body.
    The liver starts making bile this week and spleen starts helping in the production of red blood cells
  • Week 15

    Week 15
    Legs are growing longer than arms now.
    The baby can now move all of their joints and limbs.
    Can sense light and is forming taste bud.
    can tell their gender now.
  • Week 16

    Week 16
    The baby's now the size of an avocado.
    His legs are much more developed and even started growing toenails
  • Week 17

    Week 17
    The baby's skeleton is changing from soft cartilage to bone, and the umbilical cord — the lifeline to the placenta — is growing stronger and thicker
  • Week 18

    Week 18
    If the mother's having a girl, her uterus and fallopian tubes are formed and in place. If she's having a boy, his genitals are noticeable now.
  • Week 19

    Week 19
    The baby's sensory has fully developed. Their brain is designating specialized areas for smell, taste, hearing, vision, and touch.
  • Week 20

    Week 20
    The baby's length is now about the size of a banana.
  • Week 22

    Week 22
    The baby's lips, eyelids, and eyebrows are becoming more distinct, and even developing tiny tooth buds beneath his gums
  • Week 23

    Week 23
    The baby can now feel their mother's movements, see and listen to the noise and thing out side the womb.
  • Week 25

    Week 25
    The baby's beginning to exchange their long, lean look for some baby fat. As they do, the wrinkled skin will begin to smooth out and they'll start to look more and more like a newborn. She's also growing more hair.
  • Week 27

    Week 27
    The baby's now sleeping and waking at regular intervals, opening and closing her eyes, and perhaps even sucking their fingers. With more brain tissue developing, the baby's brain is very active now.
  • Week 31

    Week 31
    The baby can now turn their head from side to side, and their arms, legs, and body are beginning to plump out as needed fat accumulates underneath the skin.
  • Week 33

    Week 33
    The baby's skeleton is hardening. The bones in his or her skull aren't fused together, which allows them to move and slightly overlap, thus making it easier for them to fit through the birth canal
  • Week 35

    Week 35
    Most of the baby's basic physical development is now complete.
    The baby is now over 18 inches long about the size of a honeydew melon.
  • Week 36

    Week 36
    The baby's shedding most of the downy covering of hair that covered the body as well as the vernix caseosa, the waxy substance that covered and protected his or her skin during their nine-month amniotic bath. They swallows both of these substances, along with other secretions, resulting in a blackish mixture, called meconium, will form the contents of their first bowel movement.
    Most likely the baby is already head-down.
  • Week 37

    Week 37
    At this point the baby weighs 6 1/3 pounds and measures a bit over 19 inches, head to heel, about the size of a bunch of Swiss chard.
  • Week 38

    Week 38
    The baby's organs have matured and are ready for life outside the womb
  • Week 39

    Week 39
    The baby already measures about 20 inches and weighs a bit over 7 pounds, about the size of a mini-watermelon. (Boys tend to be slightly heavier than girls.) The outer layers of the baby's skin are sloughing off as new skin forms underneath.
  • Week 40

    Week 40
    40 weeks are the average amount of time where childbirth usually happen.
    His skull bones are not yet fused, which allows them to overlap a bit if it's a snug fit through the birth canal during labor. This so-called "molding" is the reason your baby's noggin may look a little conehead-ish after birth.