Congratulations! Pregnancy is an exciting time and a great opportunity to learn about your child's growth and development. But with so much pregnancy information available in books, in magazines, and on websites, how can you hope to cover it all before giving birth?
We've made it easy for you to get all the pregnancy info you need in one place. Our illustrated pregnancy calendar is a detailed guide to all the changes taking place in your baby — and in you! Each week of pregnancy includes a description of your baby's development, as well as an explanation of the changes taking place in your body. You'll also find important medical info that will help keep you and your baby healthy.
A word about due dates and trimesters
After you announce your pregnancy, the first question you'll probably be asked is "When are you due?" At your first prenatal visit, your health care provider will help you determine an expected delivery date (EDD). Your EDD is 40 weeks from the first day of your last menstrual period (LMP). If you deliver on your EDD, your baby is actually only about 38 weeks old — that's because your egg didn't become fertilized until about 2 weeks after the start of your last menstrual period.
It's important to remember that your due date is only an estimate — most babies are born between 38 and 42 weeks from the first day of their mom’s LMP and only a small percentage of women actually deliver on their due date.
Another common term you'll hear throughout your pregnancy is trimester. A pregnancy is divided into trimesters:
- the first trimester is from week 1 to the end of week 12
- the second trimester is from week 13 to the end of week 26
- the third trimester is from week 27 to the end of the pregnancy
Getting started
Check back every week of your pregnancy to see how your baby is developing and to find out what changes you can expect in your own body, too!
Week 1
Your baby's development
This first week is actually your menstrual period. Because your expected delivery date (EDD) is calculated from the first day of your last period, this week counts as part of your 40-week pregnancy even though your baby hasn't been conceived yet.
Your body
During pregnancy, your healthy habits and your baby's health go hand in hand. While planning to conceive, take the time to prepare your body for motherhood. Before becoming pregnant, you should:
Avoid alcohol, drugs, and tobacco products. These substances can cause birth defects, fetal alcohol syndrome, respiratory problems, low birth weight, and other health problems.
Talk to your doctor about any prescription and nonprescription (OTC) drugs you are taking. You'll need to take special precautions with medications because many prescription and over-the-counter medications can negatively affect the fetus. But don't stop taking prescription drugs without consulting your health care provider, who will help you weigh the potential benefits and risks of stopping your medications.
Maintain a diet that contains an adequate amount of vitamins, especially folic acid. Women who are attempting to become pregnant should take 400 micrograms of folic acid a day. Adequate folic acid intake reduces the risk of neural tube defects (birth defects caused by incomplete development of the brain or spinal cord), such as spina bifida. Be sure to talk to your health care provider about taking a folic acid supplement while you are trying to conceive.
Week 2
Your baby's development
This may sound strange, but you're still not pregnant! Fertilization of your egg by the sperm will only take place near the end of this week — read more about fertilization in the Your Body section below.
Although you'll have to wait to find out what color to paint the nursery, your baby's gender will be determined at the moment of fertilization. Out of the 46 chromosomes that make up a baby's genetic material, only two — one from the sperm and one from the egg — determine the baby's sex. These are known as the sex chromosomes. Every egg has an X sex chromosome; a sperm can have either an X or a Y sex chromosome. If the sperm that fertilizes your egg has an X chromosome, you'll have a girl; if it has a Y chromosome, your baby will be a boy.
Your body
Your uterine lining, which will nourish the baby, is developing, and your body secretes follicle-stimulating hormone (FSH), which stimulates an egg to mature. At the end of this week, you will be at the midpoint of your menstrual cycle (if you have a regular 28-day cycle), and ovulation will occur (your ovary will release an egg into the fallopian tube).
This is when you're most likely to conceive. If you have sexual intercourse without protection around the time that you ovulate, you can become pregnant. After your partner ejaculates, millions of sperm travel through the vagina, and hundreds make it to the fallopian tube, where your egg is waiting. One sperm generally succeeds in penetrating the egg, and fertilization takes place. When that happens, you will be pregnant — although you will not be feeling any body changes just yet.
Week 3
Your baby's development
Even though you may not feel that you're pregnant yet, you have a baby growing and developing inside of you! Although your baby was just conceived, he or she is working overtime. The fertilized egg goes through a process of cell division. About 30 hours after fertilization, it divides into two cells, then four cells, then eight, and continues to divide as it moves from the fallopian tube to the uterus. By the time it gets to the uterus, this group of cells looks like a tiny ball and is called a morula.
The morula becomes hollow and fills with fluid — it is then known as a blastocyst. Near the end of this week, the blastocyst will attach itself to the endometrium, the lining of the uterus. This is called implantation. The implantation in the uterus creates an essential connection — the endometrium will provide the developing embryo with nutrients and will remove wastes. Over time, this implantation site will develop into the placenta.
Your body
Adequate intake of certain nutrients, such as folic acid, protein, calcium, and iron, is essential for nourishing your baby. A folic acid supplement — which, ideally, you've been taking since before you conceived — is particularly important because folic acid helps prevent defects of the neural tube (the structure that gives rise to the brain and spinal cord), which forms very early in pregnancy.
Your intake of protein, which is used to create new tissue, should increase during pregnancy. In addition, calcium is necessary for the development of bones and teeth, so make sure you're getting a good dose of dairy products, leafy green vegetables, and legumes. Iron is essential during pregnancy as you support the continual increase of your baby's blood volume. Good sources of iron include red meat, legumes, eggs, and leafy green vegetables.
Week 4
Your baby's development
Four weeks into your pregnancy, your baby (called an embryo) consists of two layers of cells — the epiblast and the hypoblast — that will eventually develop into all of your baby's organs and body parts. Two other structures that develop at this time are the amnion and the yolk sac. The amnion, filled with amniotic fluid, will surround and protect the growing embryo. The yolk sac will produce blood and help to nourish the embryo until the placenta takes over that role.
Your body
This week your baby continues to implant in your uterus, burying itself deep within the endometrium. Once implanted, your baby starts to produce a hormone called human chorionic gonadotropin (hCG), which helps to maintain the lining of the uterus. It also sends a signal to the ovary to stop releasing an egg each month, which stops your monthly periods. Some women experience slight cramping and spotting of blood during this week while implantation is taking place, and they may mistake this for a period, as it often occurs around the time their monthly period was due.
hCG is the hormone that is measured in pregnancy tests. This week a pregnancy test will probably be able to detect your pregnancy! hCG also causes the symptoms of pregnancy, which can appear this week. Fatigue, tingling or aching breasts, or nausea might lead you to believe your period will be starting any day because the first pregnancy symptoms resemble premenstrual syndrome (PMS). But by the end of this week, your expected period will not take place. Your pregnancy is well on its way!
Week 5
Your baby's development
Until now, the embryo has been a mass of cells, but by this point in your pregnancy a distinct shape begins to form. The neural tube, which will eventually form into the spinal cord and brain, runs from the top to the bottom of the embryo. A bulge in the center of the embryo will develop into your baby's heart. At this time, the placenta develops. It is through the placenta and its fingerlike projections, called chorionic villi, that an embryo receives nourishment from its mother.
Your body
Even if nausea hasn't hit you yet, you'll want to steer clear of certain foods when you're pregnant. Foodborne illnesses, such as listeriosis and toxoplasmosis, may cause birth defects or even miscarriage. Here are some foods you'll want to avoid:
* soft cheeses such as feta, goat, brie, Camembert, and blue cheese
* unpasteurized milk and juices
* raw or undercooked meats, including hot dogs and deli meats
* raw eggs or foods containing raw eggs, including mousse and tiramisu
* raw shellfish
* paté
Toxoplasmosis can also be spread from soiled cat litter boxes, so try to have someone else clean the litter box during your pregnancy.
Your baby's development
Week 6
By week 6, your baby’s brain and nervous system are developing at a rapid pace. Optic vesicles, which later form the eyes, begin to develop this week on the sides of the head, as do the passageways that will make up the inner ear.
Your baby's heart will begin to beat around this time, and it may even be detected on ultrasound examination. And the beginnings of the digestive and respiratory systems are forming, too. Small buds that will grow into your baby's arms and legs also appear this week.
Because their legs are curled up against the torso for much of the pregnancy, making a full-length measurement difficult, babies often are measured from the crown to rump rather than from head to toe. This week, your baby only measures 0.08 to 0.2 inches (2 to 5 millimeters) from crown to rump!
Your body
Common pregnancy complaints may hit in full force this week. You may feel extreme fatigue as your body adjusts to the demands of pregnancy. And tender, aching breasts and nausea and vomiting (morning sickness) may leave you feeling uncomfortable. Despite its name, morning sickness can occur at any hour or all day, so don't be surprised if your queasy stomach doesn't pass by noon. Nausea isn't the only thing that has you running to the toilet, though — hormonal changes and other factors, such as your kidneys working extra hard to flush wastes out of your body, cause you to urinate more frequently, too.
Week 7
Your baby's development
Your baby is constantly adapting to life inside the uterus. By this week, the umbilical cord has formed. It will be your baby’s connection to you throughout your pregnancy, providing oxygen and nourishment for your baby and disposing of your baby's wastes. In addition, your baby's digestive tract and lungs continue to form.
Are you waiting impatiently to see your baby's face on his or her birth day? You have a long way to go until then, but in the meantime, your baby's face is taking shape. The mouth, nostrils, ears, and eyes are some of the facial features that become more defined this week.
Dreaming of a son or daughter to play ball with? The arm bud that developed just last week has a hand on the end of it, which looks like a tiny paddle.
Your body
Pregnancy causes many changes in your cervix. By this week you'll have developed a mucous plug, which forms in the opening of the cervical canal and seals off the uterus for protection. (You'll lose this plug as your cervix dilates in preparation for labor.)
Week 8
Your baby's development
Marveling over a baby's tiny fingers and toes is one of the joys of the first day of life. Those fingers and toes are just beginning to form this week, and the arms can even flex at the elbows and wrists. The eyes are becoming more obvious because they’ve begun to develop pigment (color) in the retina (back of the eye).
Also, the intestines are getting longer and there isn’t enough room for them in the baby’s abdomen, so they protrude into the umbilical cord until week 12.
By now, the beginnings of the buds that will develop into your baby's genitals have made their appearance, although they've not yet developed enough to reveal whether your baby is a boy or a girl.
Your body
Pregnancy symptoms such as a missed period, nausea, extreme fatigue, or tight clothes due to the swelling of your uterus have probably prompted you to wonder whether you're pregnant. Once you have confirmation of your pregnancy from a home pregnancy test or blood or urine test at the doctor's office, you should call and schedule your first prenatal visit. Your pregnancy may be monitored by one of several health care professionals, including an obstetrician, nurse practitioner, midwife, or family doctor. If your pregnancy is considered high risk (for example, if you have had multiple miscarriages, are older than 35, or have a history of pregnancy complications), your doctor may want to see you as early as possible and more often during the course of your pregnancy.
Good prenatal care is extremely important for the health and safe delivery of your baby, so be sure to make prenatal appointments a top priority.
Week 9
Your baby's development
The tail at the bottom of your baby's spinal cord has shrunk and almost disappeared by this week. In contrast, your baby's head has been growing — it's quite large compared with the rest of the body and it curves onto the chest. By this week, your baby measures about 0.6 to 0.7 inches (16 to 18 millimeters) from crown to rump and weighs around 0.1 ounces (3 grams). The tip of the nose has developed and can be seen in profile, and flaps of skin over the eyes have begun to shape into eyelids, which will become more noticeable in the next few weeks.
The digestive system continues to develop. The anus is forming, and the intestines are growing longer. In addition, internal reproductive features, such as testes and ovaries, start to form this week.
Your baby may make some first movements this week as muscles develop. If you had an ultrasound now, those movements might even be visible, but you won't be able to feel them for several more weeks.
Your body
In preparation for your first prenatal visit, take the time to familiarize yourself with your family's health history and to review your medical records. Have you had any chronic illnesses, allergies, or surgeries? Are you currently taking any prescription medications? Do you know of any genetic disorders that run in your family? Has your menstrual cycle been regular, and have you had any past pregnancies? Do you smoke or drink alcohol? What are your exercise habits? These are the things your health care provider will want to discuss with you, so it will help to have this information ready when you go.
week 10
Your baby's development
By week 10, all of your baby's vital organs have been formed and are starting to work together.
As external changes such as the separation of fingers and toes and the disappearance of the tail takes place, internal developments are taking place too. Tooth buds form inside the mouth, and if you're having a boy, his testes will begin producing the male hormone testosterone.
Congenital abnormalities are unlikely to develop after week 10. This also marks the end of the embryonic period — in general, the embryo now has a distinctly human appearance and starting next week your baby will officially be considered a fetus.
Your body
Your first prenatal visit, which often takes place around this time, is a milestone. At the doctor's office, you'll go through a series of tests and checks, including having your weight and blood pressure checked. You might also have an external abdominal examination to check the size and position of your baby and have your urine tested. During this first prenatal visit, your health care provider will thoroughly examine you, including an internal examination and a breast exam. Your health care provider will also ask you many questions about your medical history and any family health problems, to determine if your baby is at risk for genetic diseases. Another thing your provider will check? Your baby's heartbeat! Using a Doppler stethoscope, you should get to hear it for the first time.
As you leave your first appointment, your health care provider will probably send you for a blood test to find out whether you are immunized against varicella, measles, mumps, and rubella (German measles), as well as to determine your blood type and Rh factor.
Week 11
Your baby's development
From this week until week 20, your baby will be growing rapidly — increasing in size from about 2 inches (5 cm) to about 8 inches (20 cm) from crown to rump. To accommodate all this growth, the blood vessels in the placenta are increasing in both size and number to provide the baby with more nutrients.
Facial development continues as the ears move toward their final position on the sides of the head. If you saw a picture of your baby now, you'd think you had a genius on your hands — the baby's head accounts for about half of the body length!
Although your baby's reproductive organs are developing rapidly, the external genitals of boys and girls appear somewhat similar until the end of week 11. They will be clearly differentiated by week 14.
Your body
Nourishing your baby usually requires that you gain weight — and in most cases, the recommended weight gain is 25 to 35 pounds (11.33 to 15.87 kg) over the course of the pregnancy. If you were overweight or underweight before pregnancy, your health care provider may have different recommendations for weight gain
Week 12
Your baby's development
Your baby's brain continues to develop, and tiny fingernails and toenails start to form. Vocal cords are formed this week, which is the last of your first trimester.
Your baby's kidneys are functioning! After swallowing amniotic fluid, your baby will now be able to pass it out of the body as urine. And the intestines will make their way into the abdomen, since there is room for them now.
Your body
Has anyone told you that you have that "pregnant glow"? It's not just the joy you may feel because you're having a baby — there's a physiological reason for smoother, more radiant skin during pregnancy. Increased blood volume and pregnancy hormones work together to give you that glow. The greater blood volume brings more blood to the blood vessels and hormones increase oil gland secretion, resulting in a flushed, plumper, smoother skin appearance. Sometimes, though, the increased oil gland secretion can cause temporary acne.
Week 13
Your baby's development
As you begin the second trimester of pregnancy, your placenta has developed and is providing your baby with oxygen, nutrients, and waste disposal. The placenta also produces the hormones progesterone and estrogen, which help to maintain the pregnancy.
By now, the baby's eyelids have fused together to protect the eyes as they develop. Once you take your newborn home, you might be wishing for those eyes to close once in a while so you can get some rest!
Your baby may also be able to put a thumb in his or her mouth this week, although the sucking muscles aren't completely developed yet.
Your body
At your first prenatal appointment, your health care provider probably gave you a prescription for prenatal vitamins. Taking these supplements, in addition to eating a healthy diet, ensures your baby gets additional vitamins and minerals, such as folic acid, zinc, iron, and calcium, which are necessary for growth and development. Talk to your pharmacist about the best way to take your vitamins, such as whether they should be taken with food or beverages.
Week 14
Your baby's development
By this week, some fine hairs have developed on your baby’s face. This soft colorless hair is called lanugo, and it will eventually cover most of your baby’s body until it is shed just before delivery.
By now, your baby’s genitals have fully developed, though they may still be difficult to detect on an ultrasound examination. In addition, your baby starts to produce thyroid hormones because the thyroid gland has matured. Your baby now weighs about 1.6 ounces (45 grams) and is about 3.5 inches (9 cm) long from crown to rump.
Your body
Under certain circumstances (for example, if you're older than 35), your health care provider may discuss amniocentesis with you. Amniocentesis is a test usually done between 15 and 18 weeks that can detect abnormalities in a fetus, such as Down syndrome. During this test, a very thin needle is inserted into the amniotic fluid surrounding the baby in the uterus and a sample of the fluid is taken and analyzed. Amniocentesis does carry a very slight risk of miscarriage, so talk to your health care provider about your concerns and the risks and advantages of the test.
Week 15
Your baby's development
Parents are often amazed by the softness of their newborn's skin. Your baby’s skin has been continuously developing, and it is so thin and translucent that you can see the blood vessels through it. Hair growth continues on the eyebrows and the head. Your baby's ears are almost in position now, although they are still set a bit low on the head.
Internally, your baby's skeletal system continues to develop. Muscle development continues too, and your baby is probably making lots of movements with his or her head, mouth, arms, wrists, hands, legs, and feet.
Your body
Has it sunk in yet that you're pregnant? Many women say that it isn't until they trade in their jeans for maternity clothes and others start noticing their swelling abdomens that the reality of pregnancy sets in. For many, this realization is both joyful and scary. It's normal to feel as if you're on an emotional roller coaster (you have your hormones to thank). Another thing you may be feeling? Scatterbrained. Even the most organized women report that pregnancy somehow makes them forgetful, clumsy, and unable to concentrate. Try to keep the stress in your life to a minimum and take your "mental lapses" in stride — they're only temporary.
Week 16
Your baby's development
Your baby now weighs about 3.9 ounces (110 grams) and measures about 4.7 inches (12 cm) in length from crown to rump. Your baby can hold his or her head erect, and the development of facial muscles allows for a variety of expressions, such as squinting and frowning.
Your body
Between weeks 16 and 18 of pregnancy, your health care provider may offer you the maternal blood screening test, also known as a "triple marker" test or "triple screen," which measures the levels of alpha-fetoprotein (AFP), a protein produced by the fetus, and the pregnancy hormones hCG and estriol in the mother's blood. The test is sometimes called a quadruple test when the level of inhibin-A, is also measured. The results of these tests can tell moms whether their babies are at risk for neural tube defects such as spina bifida or chromosomal abnormalities such as Down syndrome. Out of every 1,000 women who take these tests, about 50 will have abnormal results, but only one or two women will actually have babies with a problem. Talk to your health care provider about the risks and advantages of these tests.
Week 17
Your baby's development
At about 5.1 inches (13 cm) from crown to rump and weighing 4.9 ounces (140 grams), your baby is still very tiny.
The placenta, which nourishes the fetus with nutrients and oxygen and removes wastes, is growing to accommodate your baby. It now contains thousands of blood vessels that bring nutrients and oxygen from your body to your baby's developing body.
Your body
You may notice that your breasts have changed considerably since your pregnancy began. Hormones are preparing your breasts for milk production — more blood is flowing to the breasts, and the glands that produce milk are growing in preparation for breastfeeding. This can increase your breast size (many women increase one to two cup sizes) and cause veins to become visible. Buy supportive bras in a variety of sizes to accommodate your breast growth during pregnancy.
Week 18
Your baby's development
Ears move to their final position and they stand out from the head. And start brushing up on your lullabies — in the coming weeks, your baby will probably be able to hear! The bones of the middle ear and the nerve endings from the brain are developing so that your baby will hear sounds such as your heartbeat and blood moving through the umbilical cord. He or she may even be startled by loud noises! Your baby's eyes are also developing — they're now facing forward rather than to the sides, and the retinas may be able to detect the beam of a flashlight if you hold it to your abdomen.
Until now, your baby's bones had been developing but were still soft. This week, they begin to harden, or ossify. Some of the first bones to ossify are those in the clavicles and the legs.
Your body
You're probably beginning to prepare for life with baby. Your preparations should extend beyond gathering the layette and decorating the nursery, though. This is a good week to begin your search for a pediatrician or other health care provider for your child. Schedule visits to meet with potential doctors to discuss issues such as appointment availability, immunization scheduling, and when to call in an emergency.
Some good questions to ask: How many health care providers are in the practice? Who covers nights and weekends? What is their policy on phone calls? Which hospitals are they affiliated with? What insurance do they accept? What specialists do they work with? How are emergencies handled?
It's important that you feel comfortable with your child's doctor, so do your homework and make your decision carefully.
Week 19
Your baby's development
Your baby is now covered with a white, waxy substance called vernix caseosa, which helps prevent delicate skin from becoming chapped or scratched. Premature babies may be covered in this cheesy coating at delivery.
Your baby is still tiny, but this week brings the development of brown fat, which will help keep your baby warm after birth. During the last trimester, your baby will add more layers of fat for warmth and protection.
Your body
Your constant concern for your baby's health may give way to reassurance if you feel your baby's first movements, which often happens between weeks 18 and 20. These first movements are known as quickening, and they may feel like butterflies in your stomach or a growling stomach. Later in your pregnancy, you'll feel kicks, punches, and possibly hiccups! Each baby has different movement patterns, but if you're concerned or if the movements have decreased in frequency or intensity, talk to your doctor.
Many women wonder around this time whether having sex will hurt their developing baby, and the answer is no. Sex is considered safe at all stages of pregnancy, as long as your pregnancy is normal. But that doesn't necessarily mean you're going to want to have it. Many expectant women find that their desire for sex fluctuates during the various stages of pregnancy, depending on their fatigue, growing size, anxiousness over the birth, and a host of other body changes. Keep the lines of communication with your partner open as these issues come up. Even though you may both be preoccupied with the baby, it's also important to have some "together time."
Week 20
Your baby's development
You're halfway there! Twenty weeks into your pregnancy, your baby has grown significantly from that first dividing cell and now weighs about 11 ounces (312 grams) and measures about 6.3 inches (16 cm) from crown to rump. The baby is taking up increasing room in your uterus, and continued growth will put pressure on your lungs, stomach, bladder, and kidneys.
Under the vernix caseosa (a protective, waxy coating), your baby's skin is thickening and developing layers. Hair and nail growth continue.
Your body
your health care provider may recommend that you receive an ultrasound, a diagnostic test that uses sound waves to create an image. An ultrasound can determine the size and position of the fetus, and any structural abnormalities of bones and organs that are visible by this time. Depending on the position of the fetus, the sex can usually be determined by now. During an ultrasound, the umbilical cord, placenta, and amniotic fluid can also be examined. Talk to your health care provider about the risks and advantages of this test.