Each and every cycle, your uterus works tirelessly to build up its inner layer so that if fertilization occurs it is ready to support implantation. If fertilization doesn’t happen, the uterus sheds the lining— that’s your period blood— and the process starts all over again. Your uterus is incredibly resilient.
Your uterus grows a whole new lining after shedding the previous one, just in case, there’s better luck next time or the time after that. When implantation does occur, your uterus is certainly ready to finally get to build a home for your baby, even if it needs a little outside help to get going.
Oh, and, those period cramps you may have been experiencing for years? They are actually uterine contractions. They help your uterine lining move from the uterus through the cervix and out of the vagina. During labor, uterine contractions are how you will get your baby to move from the uterus through the cervix and out of the vagina. So, while period cramps and active labor contractions may certainly feel different, it can be a nice reminder that this whole uterine contraction thing isn’t entirely new for you.