Pregnancy Week by Week

If this is your first pregnancy you might be feeling a little anxious about the process because you don’t know what to expect. Here, we go through the weeks of pregnancy, explaining what highlights occur and what to expect, which can help alleviate and concerns you might have about your pregnancy.

Weeks 1 through 4:

Basically, sperm meets egg. Well, okay, it's a little more detailed than that. Sperm penetrates the egg and fertilizes it. You may be surprised to learn that it is at the moment of conception that your baby's gender is determined. This is due to the sex chromosomes in the father's sperm.

Note that if your ovaries release two eggs and they are fertilized by two separate sperm, you will conceive fraternal twins. If your egg is fertilized by one sperm, then later divides in two, you will develop identical twins.

But, that's not all that happens during this time. It's not enough just for the sperm to penetrate the egg. Now the blastocyst (collection of cells from which the embryo forms) has to implant itself in the uterus.

Weeks 5 through 8:

This is when you may notice some early signs of pregnancy, such as a missed period. You may also notice yourself getting morning sickness, as well as an increased desire to use the bathroom as your growing uterus begins to press on your bladder. The baby is developing a circulatory system, and the heart starts to beat in the 6th week. Though only about 1/17 of an inch long, the developing baby begins to form arms and legs. Your breasts may be very tender and swollen.

Weeks 9 through 12:

By week 9 the fetus has fingers and thumbs, which are webbed. During this time you may notice yourself experiencing heartburn and indigestion, as well as your veins becoming more prominent, especially in breasts, tummy and legs. By the end of week 12, the fetus has now formed all of its organs, with the genitals beginning to take on gender characteristics. The fingers and toes have now separated. And, lucky for you, the morning sickness is subsiding.

Weeks 13 to 16:

The beginning of the second trimester, and the beginning of the most comfortable phase of pregnancy. The baby is now moving around, and you should now be able to hear your baby's heartbeat during your doctor's visit. Don't panic if you don't feel your baby moving, though, especially if you are somewhat overweight. Don't be surprised if you experience nosebleeds, as your blood volume has increased.

Weeks 17 to 20:

The baby is growing rapidly, and so are you. The average weight gain at week 17 is between 5 to 10 pounds. Your baby is starting to look human, and it's during this time you may be able to find out the baby's gender during the ultrasound.

Weeks 21 to 24: 

Your average weight gain is now 10 to 15 pounds. Your baby is now practicing breathing. As should you, as you may feel slight contractions as your uterus prepares for the delivery, as well as swollen ankles and feet. Just drink water, relax and breathe. By week 23 you're probably getting a "kick" from your baby. Your baby probably weighs over 1 pound.

Weeks 24 to 28:

It is between these weeks that you may want to take a glucose tolerance test to see if you may have gestational diabetes. You may also be experiencing some shortness of breath, as your uterus is close to your rib cage. By week 28, Your baby is now able to hear muffled sounds and sense light.

Weeks 29 to 32:

You're in the third trimester now. The baby's brain and eyes are almost totally developed. And you? You may be experiencing leg cramps, heartburn and indigestion, itchy skin, shortness of breath, achy muscles, constipation and, oh, yes, hemorrhoids. This, too, shall pass.

Weeks 33 to 36:

Starting now you're gaining about a pound a week. By week 36 you've gained about 25 to 30 pounds and your baby has grown to a length of 16 inches and weights about 5 pounds. Do be aware during this time for any signs of preeclampsia. At week 36 you're baby could come at any time.

Weeks 37 to 40:

During this time the baby drops to it's birthing position in the pelvis, and practices breathing more. Average size of the baby at week 37 is now over 6 pounds. You are really feeling the urgency to go to the bathroom constantly, as the uterus is pressing on your bladder. The baby really could come at any time, though the average is 40 weeks, with the average weight of the newborn over 7 pounds. If you haven't given birth by 42 weeks, your doctor may want to induce labor.

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