First Trimester Development

Week 3

By the end of this week, you'll notice that you've missed your period. If you have some spotting, don't worry. Many pregnant women experience a slight staining, called implantation bleeding around this time. Taking a pregnancy test in our office a day or so after your missed period can confirm your pregnancy.

Week 4

The ball of cells � now called an embryo � growing inside your uterus is the size of an apple seed. It's divided into three layers that will later form organs and tissues. Low on the sides of the head are two folds of tissue that will become the ears.

The neural tube � from which the brain, spinal cord and nerves, and backbone will sprout � develops in the top layer. The heart and the circulatory system begin to appear in the middle layer. The third layer starts to house the lungs, intestines, and beginnings of the urinary system. In the meantime, the early version of the placenta, the chorionic villi, and the umbilical cord, which delivers nourishment and oxygen to the baby, are already on the job.

If you haven't already stopped by our office for a free pregnancy test, taking one now will confirm your pregnancy. Once you get confirmation, you should call your healthcare provider and make an appointment. Good and consistent prenatal care is one of the best ways to ensure that you and the baby will be healthy throughout pregnancy.

Week 5

You may not look pregnant at this point, but your embryo's heart, no bigger than a poppyseed, has already begun to beat and pump blood. The heart is dividing into chambers, and will find a more regular rhythm soon. The embryo itself is about a quarter inch long and looks more like a tadpole than a human. It undergoes a growth spurt this week.

Major organs, including the kidneys and liver, begin to grow. The neural tube, which connects the brain and spinal cord, will close this week. The embryo's upper and lower limb buds begin to sprout � these will form your baby's arms and legs. The intestines are developing and the appendix is in place.

Below the opening that will later form the mouth, small folds exist where the neck and the lower jaw eventually develop. As early as this week, facial features are already forming. Nostrils are becoming distinct, and the earliest version of the eyes' retinas are forming.

Week 6

The embryo is the size of a small bean, about a half an inch long, this week. If you could see inside yourself, you'd find the fetus has an oversized head in proportion to its body. The embryo's facial features are forming with dark spots where the eyes are, openings where the nostrils will be, and pits to mark the ears.

Protruding buds that will become the arms and legs are even more noticeable now. The embryo's hands and feet look like paddles. Other developments include the growth of the pituitary gland and muscle fibers. You can't hear it yet, but the heart (which has divided into the right and left chambers) is now beating between 100 and 130 beats per minute.

Halfway through this week, the embryo makes its first movements. Unfortunately, you'll have to wait until sometime in the second trimester before you get to enjoy feeling your baby's calisthenics.

Week 7

Now about three-quarters of an inch long, the size of a grape, the embryo has distinct, slightly webbed fingers and toes. It's a jumping bean, moving in fits and starts. The liver is churning out large amounts of red blood cells until the bone marrow forms and takes over this role.

The eighth week marks the beginning of a very busy developmental stage. Between now and 20 weeks, your baby will be growing rapidly, and body parts that formed in the first few weeks of life (such as the heart and brain) will become more specialized and complicated. Right now, the teeth and palate are forming, while the ears continue to develop. The fetus' skin is paper thin, and veins are clearly visible.

You're in the throes of the first trimester, when many women complain of common pregnancy aches and pains. Keeping food down may be next to impossible, thanks to morning sickness, caused in part by the pregnancy hormones in your body. You may also need to use the bathroom a lot more often than usual � your growing uterus is pressing on your bladder, and hormones are affecting the balance of fluid in your body. These symptoms should diminish as your pregnancy continues.

Week 8

If you haven't already, you may soon find yourself riding pregnancy's emotional roller coaster, feeling moody one day and joyful the next. Disturbing as this is to some women who pride themselves on being in control, what you're going through is normal and will probably continue throughout your pregnancy. Up-and-down emotions are partly caused by fluctuating and (in many cases) very high levels of hormones.

Your pregnancy is changing your figure as well. Your breasts have grown large enough that you'll need bigger bras with better support than your old ones. You may notice your waistline expanding as well, forcing you to pack away your favorite jeans until next year. If you drink plenty of fluoridated water � eight glasses or more a day � you should be getting enough fluoride so calcium and phosphorus will bond well in your baby's developing teeth and bones.

Week 9

Congratulations � your embryo is now called a fetus, which means "little one." Your uterus expands to accommodate its new resident, which now measures approximately one inch. Many changes take place this week � the embryonic tail is gone and all organs, muscles, and nerves are beginning to function. The hands now bend at the wrist, and the feet begin to lose their webbed appearance. Eyelids are beginning to cover the eyes.

In both shape and size, your baby resembles a lima bean. The eyelids are fused and won't open until week 27. The wrists are more developed, ankles have formed, and the fingers and toes are clearly visible. Arms are growing longer and bend at the elbows. By week's end, the inner workings of the ears are complete. Though you can't yet identify the sex yet by ultrasound, the genitals have begun to form. By now the placenta has developed enough to support most of the critical job of producing hormones.

If you're over 35 or have a family history of genetic illness, you may want to consider a chorionic villus sampling (CVS), a prenatal test usually given between ten and 12 weeks that screens for birth defects and abnormalities.

Week 10

Though the fetus is only about 1 to 2 inches long crown to rump and weighs less than half an ounce, it's busily swallowing and kicking. Each day more minute details start to appear, such as fingernails and peach-fuzzy hair. The vital organs � the liver, kidneys, intestines, brain, and lungs � are fully formed and functional, while the head is almost half the length of the entire body. The forehead temporarily bulges and sits high on the head, but later will metamorphose into a more human-like visage.

If you could take a peek at your baby this week, you'd be able to see the clear outline of his spine. Spinal nerves stretch out from the spinal cord.

Your uterus is now the size of a grapefruit. With the help of a Doppler, a handheld soundwave stethoscope, you can hear the fetus's rapid heartbeat � one expectant mother likened it to the sound of tiny horses galloping.

Week 11

You're getting close to the end of the first trimester. Most of the baby's critical development will be behind you after the next couple of weeks, and the odds of miscarriage will soon drop considerably. Your baby has all his parts, from tooth buds to toenails, and is busy kicking and stretching, and his movements are so fluid they look like water ballet. Fingers and toes have fully separated. Now the fetus's main task during the next six months will be to grow larger and stronger until it can survive on its own outside the womb.

A dark vertical line of pigmentation, called the linea nigra, may appear on your abdomen. Your uterus has risen above your pelvic bones, and your healthcare provider can now feel it during an external examination.

Week 12

Your baby's face is beginning to look more human, even though he is only about 3 inches long and weighs slightly more than half an ounce. The eyes, which started out on the sides of the head, have moved closer together. The ears are almost in their normal position on the side of the head. The liver is making bile, and the kidneys are secreting urine into the bladder.

The fetus squirms if your abdomen is prodded, though you cannot yet feel movement. Fetal nerve cells have been multiplying rapidly, and synapses (neurological impulses in your brain) are forming. The fetus has acquired more reflexes: Touching the palms makes the fingers close, touching the soles of the feet makes the toes curl down, and touching the eyelids makes the eye muscles clench.

Your healthcare provider can now feel the top of the uterus, also known as the fundus, low in the abdomen. As you enter the second trimester, you may find yourself donning looser, less restrictive clothing. Soon you won't be able to fit into your regular clothes anymore.

Second trimester
Third trimester
Labor & delivery
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Northeast Georgia Life, 2004