An infant.
You call the baby whatever its parents named it.
In the first two months, the baby is called an "embryo". But from that period on to the birth, the baby is called a "fetus."
two months after you get married your character or your wife will feel ill and it turns out you or she is pregnant and two months after that she will have a baby
22 months. Two months short of two years.
Baby snow owls are called owlets. They are born covered in fluffy white down feathers and stay with their parents for around two months before they start to explore on their own.
Your partner
From week 38 and/or when he's born he is called a baby.
4 months
Two people come together have sex and in nine months a baby pops out
Full Term.
A young sloth is called a baby sloth or a slothlet. It typically stays with its mother for around six months to two years before becoming independent.