When you conceive the fertilised egg travels down one of your fallopian tube and into the uterus. There it lands on the surface of the uterus, which has a rich blood supply and burrows into the lining of your uterus. This embryo quickly needs oxygen and energy to make the miraculous change from a few cells to a fully developed baby.
A structure called a placenta develops in the lining of your womb it grafts itself onto the lining of the uterus with a blood supply that allows oxygen and energy to pass from your blood supply to your baby’s blood supply.
Oxygen and energy (fats, carbohydrates, proteins) travel from the placenta into the baby.
The umbilical cord carries nutrient rich oxygenated blood you’re your baby and is attached to your baby’s belly button. Your baby’s lungs cannot work until they are born and take their first breath. Until birth, all oxygen comes via the baby’s umbilical cord.
All the waste products coming out from your baby come back out through the umbilical cord, through the placenta, then back into your bloodstream as well, for your body to dispose of. This means your baby doesn’t poo until after they are born (sometimes if they are experiencing stress they may poo meconium into the amniotic fluid).
Like other mammals a woman’s body has evolved over millions of years to safely grow their baby inside their body and provide them with all the oxygen and nutrients over the 40 weeks until they are fully developed, able to breathe and feed.
If a baby is born very prematurely they will need medical help to feed them and sometimes to help them breathe (if their lungs haven’t been fully developed). What mothers’ bodies do so effortlessly, an incubator tries to copy by providing warmth, oxygen, and food until the baby is able to breastfeed, breathe and regulate their own body temperature.
If your baby is born prematurely your body will also be very good at regulating your baby’s temperature and breathing with lots of skin to skin contact. In fact, this form of kangaroo care was trialled in Equador when they had an incubator shortage and has been found to be better at regulating babies’ body temperatures and breathing. So mums bodies are great at supporting babies even after a premature birth. Lactating will also begin earlier so that when your baby is able to suck they will be able to breastfeed. The colostrum you produce will be the perfect food for your premature baby and can be given by tiny syringe until they can latch on and breastfeed themselves.
Mum Melissa talks about the difference in the trimesters of pregnancy here: