From Conception to Birth – Your 42 Week Pregnancy Calendar

Congratulations – you are going to have a baby. Your life is about to change in many wonderful ways, and your body will be undergoing many changes over the next weeks and months. As a mom to be it is important for you to know what to expect when you are expecting, and this pregnancy calendar is designed to do just that.

Week 1

It may seem odd, but week one actually starts with your monthly menstrual period. That is because your due date is calculated based on the first day of your last period. At this point your baby has not yet been conceived, but there are some steps you can take to keep yourself – and your future son or daughter – healthy.

That’s because your health and the health of your baby go hand in hand. If you are actively trying to get pregnant it is important to avoid things that could harm the development of your baby. Avoiding alcohol and other drugs is essential at this point – the presence of alcohol or drugs in your system at the time of conception could have a profound effect on the developing fetus.

It is also important to talk to your doctor about any medications you are taking, including over the counter medications and even herbal remedies. Even seemingly innocuous medications could have an effect on your baby, or on your ability to conceive, so it is important to let your doctor know you plan to get pregnant.

Week 2

Fertilization will take place this week, and by the end of the week you will be officially pregnant. Even though you will not know your baby’s sex for many more weeks, the gender of your baby will be determined the moment the egg and sperm meet.

Even before your baby is conceived, your body will be getting ready to host its new resident. The uterine lining that will serve as nourishment for the growing baby is beginning to develop. Your body will also secrete a follicle stimulating hormone designed to help the egg mature. When the egg is mature ovulation will take place, and at this point you will be the most fertile. If you are trying to have a baby, now would be the perfect time for a romantic dinner followed by a night of passionate lovemaking.

Week 3

At this point you most likely do not realize you are pregnant, but in fact a new life has begun to grow inside you. Your baby has just been conceived, but he or she is getting off to a great start. At this point the fertilized egg has begun to divide exponentially, turning one cell into two, then four, then eight and so on. The cell division will continue as the fertilized egg travels down the fallopian tubes into the uterus. By the time the fertilized egg has reached the uterus the clump of cells resembles a tiny ball.

This ball of cells will become hollow and filled with fluid, at which point it is known as a blastocyst. By the end of week three the blastocyst will become attached to the lining of the uterus in a process known as implantation. The lining of the uterus will provide vital nutrients to the fetus as it grows and develops.

During this time it is important for moms to be to get plenty of good nutrition, particularly nutrients like folic acid. Folic acid is particularly important for the growing fetus, playing a role in the prevention of many common birth defects. Since you probably don’t yet know you are pregnant, it is important to eat right at all times, both for your own health and that of your future son or daughter.

It is also a good idea to increate the amount of protein in your diet when you are trying to conceive. This added protein will play a big role in the development of your baby. Extra calcium is important as well, both for your own bone health and the development of your fetus. Be sure to eat lots of quality dairy products, dark green vegetables and other calcium rich foods.

Week 4

At four weeks your baby has morphed from a blastocyst into an embryo. The embryo is made up of two distinct layers of cells and these cells will eventually develop into all of your baby’s organs. At this point in development the yolk sac and amnion will develop as well. The amnion will be filled with amniotic fluid, which will surround that embryo and protect it. The yolk sac produces the blood needed to nourish the embryo at this point. Later in the pregnancy this vital role will be taken over by the placenta.

During this stage of development the embryo will be burying itself deep into the walls of the uterus. Once the embryo is fully implanted it will start to produce a hormone known as human chorionic gonadotropic, or hCG. This hormone will serve to maintain the lining of the uterus, and it will also signal the ovaries to stop releasing eggs. This is why your period stops after you have conceived.

During this period some women may feel some slight cramping and a bit of spotting, and sometimes this spotting is mistaken for the monthly menstrual cycle. If you are unsure about your pregnancy status it is a good idea to take a pregnancy test. Home pregnancy tests look for the presence of the hCG hormone, so you should be able to get an accurate result at this time. If the results of the home pregnancy test are unclear it is a good idea to make an appointment with your gynecologist.

Week 5

At week five the embryo that had been an indistinct clump of cells has begun to take on a definitive shape. By week five the embryo will have developed the neural tube that will eventually become the baby’s brain and spinal cord. The embryo will also have a distinct bulge in the middle where the heart will eventually form. It is also during this time that the placenta will develop and take over the job of nourishing the baby.

It is also at this point that moms to be may feel the first signs of nausea and morning sickness. Some women are greatly troubled by these symptoms, while others may see virtually nothing. Nevertheless it is a good idea to avoid foods that often trigger morning sickness. These problem foods include soft cheeses like blue and brie, juice, hot dogs, deli meats, raw shellfish and raw eggs.

Now is also the time to pass the job of cleaning the litter box on to your partner. Cat feces can carry a disease known as toxoplasmosis, which can be very dangerous to the developing fetus.

Week 6

By the sixth week the embryo’s brain and nervous system are starting to develop in earnest. At the same time the precursors of the eyes, known as optic vesicles, are starting to develop on the sides of the head.

At this point the baby’s heart will start to beat, and you may even be able to pick up this heartbeat during your ultrasound exam. The precursors of the respiratory system and digestive system are also forming at this time, as are the small buds that will develop into the baby’s arms and legs. At this point your baby is still quite small, probably about 2 to 5 millimeters in length.

By week six many moms to be may be seeing some of the more unpleasant signs of pregnancy, including fatigue and nausea. Although most of us are familiar with the term morning sickness, this sudden nausea can appear at any time, so be prepared.

You may also find that your breasts have become quite tender, and you may find yourself urinating more than normal due to hormonal changes that can affect your kidneys. If you find yourself feeling unwell and run down just think about your baby and the joy he or she will bring to your life.

Week 7

At this point your baby is adapting well to its life inside your body. By this time your baby’s umbilical cord has already formed, and this cord will serve as a lifeline to you throughout the pregnancy. The umbilical cord will provide vital oxygen and nourishment for the fetus throughout the pregnancy and help to dispose of any waste products.

Your baby’s face will also be forming at this point, as the mouth, eyes, ears and nose become more defined and recognizable. The baby’s digestive system and lungs are also continuing to form as week seven rolls around.

During the seventh week of pregnancy you will have developed a mucous plug at the opening of your cervical canal. This plug forms as a part of pregnancy, and its job is to seal off and protect the uterus and its precious cargo. This plug will eventually be lost as the cervix dilates in preparation for the delivery of the baby, but that is still a long way off.

Week 8

By the eighth week of pregnancy the baby’s fingers and toes have just begun to form. At this point your baby is able to flex his or her arms at the elbow and the wrist. The digestive tract is continuing to grow as well, with longer intestines and a more pronounced abdomen. The eyes are continuing to develop as well, and they have even started to develop a bit of pigment.

At this point the buds that will become the baby’s genitals are even becoming apparent, although these features will not be distinct enough to accurately determine if you should paint the nursery pink or blue.

During this period you will continue to experience the symptoms of pregnancy, including extreme tiredness, nausea and swelling of your abdomen. Now is also the time to schedule your first prenatal exam. As soon as your pregnancy is confirmed it is important to have a thorough exam and pay careful attention to the advice of your doctor. Proper prenatal care is particularly crucial during the early weeks of your pregnancy.

Week 9

At this point your baby still has a tail, but that tail has begun to shrink and will eventually disappear altogether. The baby’s head continues to grow, and it will appear quite large for the body. By this week your baby will be between 16 and 18 millimeters in length, and you will be able to see the flaps of skin that will develop into his or her eyelids.

Your baby’s digestive system is continuing to develop as well, and the intestines are continuing to get longer. The anus has now formed as well, as have the reproductive organs, including the testes or ovaries. Your baby may begin to move at this point, so be on the lookout for these exciting signs of life.

Now is the time to start researching your family medical history, paying careful attention to any genetic problems or hereditary diseases. Be prepared to discuss your family history with your doctor at your first prenatal exam. Also discuss any medications you are taking, including not only prescription medications but herbal remedies and over the counter preparations as well.

Week 10

By the tenth week of development all of your baby’s vital organs have formed and they are all beginning to work together. Other changes, like the separation of the fingers and toes, will have taken place as well. At this point your baby’s vestigial tail will have disappeared completely, and tooth buds will be forming in his or her mouth. If the baby is a boy his testes will have already begun to make testosterone, so be prepared.

The tenth week of pregnancy also marks the end of the embryonic period. By this time the baby is now fully recognizable as a human being, and beginning with week 11 he or she will officially be called a fetus.

During this week you may be having a prenatal visit, complete with a full battery of tests. You will probably have your blood checked and your blood pressure evaluated during your exam, and you may also have an external abdominal exam to determine the size of the baby and his or her position in your uterus. You may also be asked for a urine sample so that other important tests can be done. If you have a genetic predisposition to certain diseases or a family history of congenital conditions you may be asked to undergo further testing.

Week 11

As week 11 arrives your baby will have started to grow quite rapidly, and by now he or she is about two inches long. At the same time the blood vessels in your placenta are expanding to accommodate the growing fetus. The placenta is also increasing the number of blood vessels in order to provide more nourishment as the baby continues to grow.

The development of your baby’s face is continuing as well, and by now most facial features are easily recognizable. At the same time the baby’s head continues to be disproportionately large for its body, making up about half of the total length of the body.

Your baby’s reproductive organs are growing rapidly as well, but it will still be difficult to determine the gender. At this stage of gestation the external genitals on male and female fetuses can look quite similar, so don’t start painting the nursery just yet.

By this stage of your pregnancy you will probably have put on some weight, since your baby will need extra nutrients to continue his or her growth. In most cases a good guideline for weight gain is between 25 and 35 pounds over the course of your pregnancy, but it is important to talk with your doctor about what you can expect in terms of your weight.

Week 12

At twelve weeks of gestation your baby’s brain will be undergoing a period of rapid growth, ready to fill that big head. Your baby will also begin to sprout fingernails and toenails at this point.

As the end of the first trimester approaches your baby will have functional kidneys, allowing the fetus to pass urine. The umbilical cord will remove these waste products while providing much needed oxygen to help your baby continue his or her development.

It is at this point that many moms to be will develop that distinctive glowing appearance. While some of this glow is due to the excitement of impending motherhood, it can also be a result of increased blood flow and extra hormones. Unfortunately these hormonal changes can also cause acne in some women. While it may be unpleasant it is important to treat this pregnancy-related acne with care. Before using any treatment it is important to check with your doctor, since some acne treatments can be harmful to your baby’s development.

Week 13

As the second trimester gets underway the placenta will have developed fully and it is now providing the baby with nutrients, oxygen and a well developed waste disposal system. The placenta will also be pumping out hormones like progesterone and estrogen - hormones that will help to maintain the pregnancy. At this point your baby has eyelids in place to protect the eyes, and at this stage many babies will begin to such their thumbs.

You have probably been taking prenatal vitamins on the recommendation of your doctor, and hopefully you have been eating a healthy and balanced diet. All of these extra nutrients are serving your baby well, helping in the growth and development of the young fetus. It is important to keep going to your prenatal appointments and to keep following the recommendations of your doctor.

Week 14

By the fourteenth week of development your baby may have some hairs on the face or body. As growth continues these fine hairs, known as lanugo, will come to cover most of the baby’s body surface. This protective coating will be shed just before your baby is born.

Your baby now has fully formed genitals, so at this point you will be able to determine whether you will be having a son or a daughter. Some parents are just dying to know which color to paint the nursery, while others prefer to wait for the big surprise. This is an important decision, and one only you and your partner can make.

If you are over the age of 35 your doctor may talk to you about amniocentesis. This procedure is typically performed between 15 and 18 weeks of gestation, and it is able to pick up many genetic abnormalities. The odds of many birth defects increase with the age of the mother, so if you are having a baby later in life you may want to consider this procedure. Amniocentesis does carry a slight risk of miscarriage, so it is essential to weigh these risks against the potential benefits.

Week 15

At this stage of gestation your baby’s skin is continuing to grow, providing important protection to those delicate internal organs and structures. Your baby will also be growing additional hair, including eyebrows. Facial features continue to form as well, and at this stage your baby’s ears are nearly in place, although they are still a bit lower than they will be on the newborn.

The skeletal system is continuing to grow as well, as are the muscles that will power that tiny skeleton. At this point your baby is probably moving around a great deal, and you may even be able to feel some of those movements.

By now you will probably be ready to trade in those traditional clothes for looser fitting maternity wear, as your stomach will have greatly increased in size. As your abdomen continues to swell it is important to wear clothes that are comfortable and loose fitting.

By this point you may also find that those pregnancy hormones have kicked into high gear. You may find that you are on an emotional roller coaster from time to time, up one minute and down the next. Try to take it all in stride, content in the knowledge that you will be meeting your new son or daughter very soon.

Week 16

By now your baby weighs approximately four ounces and measures nearly five inches in length. At this stage of development your baby can hold his or her head up, and the facial muscles are developed to the point where common expressions may be visible. Your baby can squint, frown and maybe even smile.

At this point in your pregnancy you may be offered a blood screening test called a “triple screen” or “triple marker” test. This specialized maternal blood test is designed to measure the levels of a protein in the baby’s blood, along with two hormones in the blood of the mother. These test results can provide an indication that the baby is at risk for common birth defects like spina bifida or Down syndrome. Chances are your baby will pass these tests with flying colors, but it is a good idea to talk to your doctor about the value of this screening.

Week 17

By now your baby is over five inches long and nearly five ounces in weight. Even after all these weeks of development your baby is still quite small, but he or she will be growing a great deal over the coming weeks and months.

By now the placenta that provides such important nourishment is growing larger to accommodate your growing baby. This vital source of nutrients contains literally thousands of blood vessels which bring nutrients to the growing fetus.

At this point in your pregnancy you may be noticing a distinct swelling in your breasts as the pregnancy hormones coursing through your body prepare for milk production. These changes can increase the size of your breasts, so you may find yourself shopping for a new bra.

Week 18

At 18 weeks of gestation your baby’s ears will have moved to their final position on the head, and the ears will now stand out from the head instead of lying flat. In fact your baby can probably hear sounds at this point, so why not sing your son or daughter a lovely lullaby?

Your baby’s eyes are continuing to develop as well, and those eyes are now facing forwards instead of being stuck off to the sides. In fact those eyes may be sensitive enough to detect the light of a flashlight placed against your growing belly. At this point in the development your baby’s bones will have begun to harden. The bones in the legs are among the first to harden, but the others will soon follow suit.

At this point you are probably starting to prepare for the arrival of your new baby. You may have started to work on the nursery, and you may already be shopping for baby clothes, a crib and other essentials. While you prepare for your new son or daughter it is a good idea to also start shopping for a good pediatrician.