Pregnancy Week 12 – The Baby’s Progress

The end of pregnancy week 12 marks the end of your first trimester so it is now far less likely that your baby will be able to develop any congenital disorders. As her spinal cord has now formed and messages are being received to the muscles, her movements will be more fluid now from the earlier ‘flickerings’ and she will display advanced movement of the head, mouth, wrists, arms, hands, thumbs, legs, feet and toes as she practises flexing, bending, grasping, breathing and sucking. Techniques such as these will be required in order to survive the transition to the outside world.

Developing 12 Week Fetus

Once you reach the pregnancy week twelve phase, the placenta will have taken over from the tiny yolk sac in maintaining and supporting the baby’s life throughout the remaining months of gestation by filtering oxygen and nutrients from the mother, received via the umbilical cord, and safely secreting the baby’s waste. The placenta is a disc-shaped organ that is around 3 times the size of the fetus. By the time the baby is born it will only be a third of the baby’s weight. The spleen has now began to function, supervised by the liver, in removing red blood cells and producing antibodies.

Some women worry that the umbilical cord can become knotted or damaged once the baby begins moving around. The cord is actually thick and rubbery so any entanglement that may occur will not normally be able to tighten and should not cause any problem. It is also coiled like a spring as the protective sheath that covers it is longer than the blood vessels contained inside so this will allow for plenty of movement from your baby without the risk of damaging their lifeline.

The neck and shoulders have become a lot more defined now with vocal cords appearing in the lengthening neck and the stomach now clearly linked to the mouth and intestines of your 12 week fetus. Sucking muscles now plump the cheeks out and salivary glands have began to form. The baby inhaling and exhaling amniotic fluid will continue now as this is an important way for air sacs to develop within the lungs and constant moving is also essential for the baby to further mature the muscles and nervous system. The multitude of reflexes the baby has will continue developing throughout now until she is born.

Pregnancy week 12 what to expect – your baby is now roughly 2.5” (64 mm) crown to rump and weighs around 0.88 oz (25g).

Congratulations, now you can tell everyone that you are pregnant – if they haven’t already guessed for themselves.

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(See 12 Weeks Pregnant – The Mother’s Progress)


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