Live Science is supported by its audience. When you purchase through links on our site, we may earn an affiliate commission. .Within seconds of birth, a baby takes in its own oxygen for the first time. For that to happen, their tiny lungs and circulatory system have to transform in a matter of seconds. So how does a tiny human manage to take what could be the most challenging breath of its life just seconds after birth? First, it helps to understand how the — specifically, the and heart  — work in utero. The lungs don't provide to the fetus during gestation. Instead, they are...…Live Science is supported by its audience. When you purchase through links on our site, we may earn an affiliate commission. .Within seconds of birth, a baby takes in its own oxygen for the first time. For that to happen, their tiny lungs and circulatory system have to transform in a matter of seconds. So how does a tiny human manage to take what could be the most challenging breath of its life just seconds after birth? First, it helps to understand how the — specifically, the and heart  — work in utero. The lungs don't provide to the fetus during gestation. Instead, they are...WW…