When your baby is born she’s experienced three amazing periods of growth and development inside the womb known as trimesters. But experts have coined the three to four months after birth the 4th trimester because it is a critical, complex and confusing time of continued growth and navigation of life on the other side of mom’s belly.
Today we’re exploring the 4th trimester and sharing what you need to know to help your baby thrive – and yourself survive – this crucial stage.
From Womb to World
Think about how warm and snuggly your baby must have been curled up in your uterus, floating to her heart’s content in her dim cave. The sound of your heartbeat and other bodily functions were music to her ears and your movements rocked her peacefully day and night. She had plenty of sustenance and never wanted for anything.
Then, suddenly, your baby is born into a great big world where there is space everywhere, it’s cold, bright, still, quiet and she has to work for her food. Her senses are not developed, her instincts are not sharp, and her brain is still much too small to work through her problems alone. She needs major support – thank goodness she has you, mom!
The Science Behind the 4th Trimester
The 4th trimester is all about transitioning from the womb to the world and overcoming the challenges that major move brings. While it seems silly to call it a 4th trimester when trimester inherently means only three, there is science and evolution behind the theory.
Before humans were humans and walked upright, babies gestated for three or four months longer and were better able to handle life outside their mothers’ bodies when their birth days finally arrived. Becoming bipedal caused the pelvis to narrow and babies had to be born earlier so they would be small enough to fit through the birth canal. But their brains and nervous system were not yet ready to cope with the outside world.
Unlike other mammals, human babies are born with approximately 25% of the size of their adult brain. Most mammals are born with 60% to 90% of their adult brain size. This allows many of them to have better survival instincts and functions at birth, such as being able to run, hunt or eat their species’ regular diet relatively quickly.
On the other hand, human babies are rather helpless and need constant attention and support for their every basic need. Babies cry the most during the 4th trimester because it is their only form of communication. Their cries are not only to signal hunger, discomfort and need for affection, but also to block noises and stimulus that is too much for their tiny nervous system to handle. It’s not until around four months of age that babies can learn to self-soothe.
Stick around later this week for more fascinating facts about the 4th trimester including how you and your baby can embrace this special time together.
Sources: Baby Center and Parent Map