First Trimester
1st and 2nd Weeks of Gestation 
Ovulation Occurs
3rd Week of Gestation 
Fertilization occurs as the sperm meets the egg
4th Week of Gestation 
The Blastocyst splits to form the placenta and the embryo
5th Week of Gestation 
The fetal heart and circulatory system are developing. Your Pregnacy test will be postitive because your HCG hormone level is elevated
6th Week of Gestation 
The fetal face is forming
7th Week of Gestation 
The fetal brain is now forming
8-12 Weeks of Gestation 
As your baby starts moving in the womb, morning sickness (which doesn't just strike in the morning) may have you moving to the bathroom.
Your baby is busy building muscle, but all you may want to do these days is take a nice long nap. On your baby's to-do list this week: Build bones and cartilage. On your agenda, increase your fiber intake to cope with pregnancy constipation.
That adorable little alien inside your tummy is starting to look human about now, as you start feeling a bit more human yourself.
While it may seem as if you've doubled in size over the past few weeks with pregnancy weight gain, it's your baby who actually has!
Second Trimester
13-16 Weeks of Gestation 
As the first trimester comes to a close, your baby's about the size of peach, though you may not be feeling too peachy about your sex life right now.
It's all about hair now as your baby sprouts some on his head, eyebrows, and body. As for Mom, those first-trimester pregnancy symptoms should be easing up a bit.
You might not yet be feeling it, but your baby is kicking those little legs and flexing those elbows, while higher up you may be coping with some dental weirdness.
Your baby's eyesight (and eyelashes!) is developing rapidly, but all you might be seeing in the mirror these days is a body that looks depressingly bulky.
17 - 20 Weeks of Gestation 
Your baby is practicing sucking and swallowing as she gets ready for the real thing: a breast or bottle! As for Mom, you may be warding off some unwanted belly touching.
You might start to feel your baby moving around anytime now, which is a great way to take your mind off your bothersome back.
Your baby's skin now has a protective coating, while you might be hoping for something to protect you from painful leg cramps.
Boy or girl? You can find out this week through a routine ultrasound!
21 - 24 Weeks of Gestation 
Your baby is grazing on whatever you are right now, but those stretch marks are yours alone, Mom. These days, the only things growing more rapidly than your baby's senses may be her mommy's feet!
Baby is getting (a little) plumper, but Mommy may notice something completely different when she glances at her own belly: the linea nigra.
Your baby's facial features are really filling out and your belly button may be really popping out!
25 - 28 Weeks of Gestation
As baby prepares to take his first breath, pesky hemorrhoids may make you swear under yours.
Major excitement: Your baby opens her eyes! On the flip side, you might wish yours would stay closed so you could get some sleep.
Your baby moves on to a whole new growth chart this week, while your swollen feet and ankles may need a growth chart of their own!
Your baby has started blinking and dreaming while you may be dreaming that the pain in your derriere will disappear!
Third Trimester
29 - 32 Weeks of Gestation 
Your baby's packing on the pounds, which look so cute on her. If only you could say the same for your varicose veins
Your baby's brain is getting smarter by the minute, but for Mom, the only thing that smarts right now may be heartburn pain. 
As your baby's senses increase, his mommy's breathing room decreases.
Your baby is practicing survival skills like sucking and breathing, while your uterus is practicing some Braxton Hicks contractions.
33 - 36 Weeks of Gestation 
Your baby's immune system gets a boost, while her sleepless mommy could use a boost of energy.
A boy baby's testicles descend this week (whoopee!), but Mom should also look out below - and above - as her vision becomes less sharp.
A rapidly growing brain makes your baby's head weigh more and that means more pressure on Mommy's bladder.
Your baby's bones may be ready to rock and roll, but yours may be aching something awful right now.
37 - 40 Weeks of Gestation 
Your doctor may check for labor signs, while your baby prepares for birth by sucking, turning, and breathing in the womb.
Your baby is producing surfactant, which will help him take those first breaths while you're producing colostrum, the precursor to breast milk.
Your baby's brain development is still in high gear, even as you may start to experience some definite signs of labor.
It's the official end of your pregnancy - though your baby might not have gotten that memo. Hang in there!
