Your body begins to develop the placenta and amniotic sac in week 4 of pregnancy. This week, you may notice symptoms like stomach pain and sore breasts, when the clump of cells that will soon become your baby burrows into your uterine lining. You may also notice some implantation bleeding. (However, if you haven't seen any symptoms yet, that's perfectly normal as well.)

Are you exhausted? Many pregnant women experience fatigue around week 9 of their pregnancy. What is the (extremely essential) reason? During the first trimester, your body is working tirelessly to build the placenta, which serves as a lifeline between your baby and your own blood flow.

Pregnancy week 13 marks the end of the first trimester. (How amazing is it that you're already one-third of the way through your pregnancy?) Most expectant parents start spreading the news around the 13th week of pregnancy, but when you decide to do so is entirely up to you and your loved ones.

Are you starting to feel hungry? It could be pregnancy hunger pangs, or it could be the first sign of fetal movement, which can happen around week 18 of pregnancy.

Your baby can now hold things better, see better, and hear better. By week 22 of your pregnancy, your baby has also reached a big milestone: he or she has weighed more than 1 pound. Still, you may be noticing more changes, like a belly button that sticks out and maybe even a little bit bigger feet. This is because of the hormones and pregnancy swelling (called edema).

Hurrah! You've made it to the last week of the second trimester, which means the finish line is in sight. However, your infant is developing talents of his/her own, and I think it's safe to say that your voice is music to his/her ears. You shouldn't be alarmed if you start feeling flutters in your expanding tummy. Your baby may be experiencing hiccups.

At 31 weeks pregnant, your baby's brain is developing rapidly, and he or she is more active than ever before, pedaling their feet, sucking their thumbs, and perfecting other abilities that will be essential in the outside world. You could be becoming tired more quickly and having to use the restroom more often.

We've reached the end of the eighth month of pregnancy and the beginning of the ninth. Your unborn child's hearing has improved, allowing him to eavesdrop more, and he may now be moving lower in your pelvis. Due to the release of relaxin and progesterone in the last week of pregnancy, women may have increased mobility in their joints (and, less ideally, pelvic discomfort) in the days leading up to birth.

You are now in the ninth month of pregnancy, even though you are 40 weeks along (even if it feels like longer). Your newborn is ready for the world outside the womb, with all systems (including organs and reflexes) operational. If you've past your due date, you're not alone. A third of all pregnancies will last the full 41 weeks.