The first three months of pregnancy are marked by incredible changes inside as a new life takes hold. Click on each week for detailed information on Your Baby and Your Body. Each week also has a featured image for you to view.

Week 1

Your Baby:

This first week actually begins with your menstrual period. Your estimated due date is calculated from the first day of your last period, so this week counts as part of your 40-week pregnancy even though your baby hasn’t been conceived yet.

Your Body:

Technically, you are not pregnant yet because sperm and egg have yet to meet. Your uterine lining is shedding itself to prepare for the next ovulatory cycle. If you are trying to conceive it’s important to make healthy lifestyle choices including a well-balanced diet and abstaining from smoking and drinking alcohol. It’s advantageous to begin taking prenatal vitamins, folic acid, and to get adequate rest prior to pursuing pregnancy.

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Week 2

Your Baby:

Your body is gearing up for ovulation. The lining of your uterus is thickening, preparing for the arrival of a fertilized egg, while your ovarian follicles are maturing. The average ejaculate contains approximately 50 to 200 million sperm, one of which will determine your baby’s gender at the moment of fertilization.

Your Body:

The increase in estrogen production prior to ovulation causes your cervical mucus to become clear and stretchy. This facilitates the transport of sperm into the uterus and fallopian tubes. If you have unprotected sex during your fertile window, one of the millions of sperm may succeed in penetrating the egg and fertilization will occur.

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Week 3

Your Baby:

The fertilized egg, now called an embryo, will begin dividing while traveling through the fallopian tube for five to six days before it reaches the uterine cavity.
When the embryo reaches the uterine cavity it contains 100 or more cells and it is now referred to as a blastocyst. When the blastocyst attaches to the uterine lining, implantation has occurred.

Your Body:

During the six day journey through your fallopian tube the embryo (your fertilized egg) is dividing rapidly as a growing cluster of cells. Higher levels of estrogen and progesterone are being produced to prepare the uterine lining for implantation of the embryo. After implantation, the pregnancy hormone hCG is produced. At this time, you may confirm your pregnancy with a blood test.

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Week 4

Your Baby:

About the size of a poppy seed, the embryo has “hatched” out of its outer shell and the cells continue to divide. Nourishment is being provided by a separate structure called the the yolk sac until the placenta takes over.

Your Body:

The implanted embryo continues to develop in the endometrium (lining of the uterus). The production of the pregnancy hormone hCG continues to increase and is now often detectable with an over the counter urine pregnancy test approximately 15 to 20 days after fertilization. Many women experience implantation bleeding which may appear as light pink, red or brown spotting. Generally, this is nothing to worry about but it can be mistaken for a period when coupled with other early pregnancy symptoms like bloating and tender breasts.

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Week 5

Your Baby:

Your baby is now about the size of an apple seed. The umbilical cord begins to develop and transport nutrients from you to your developing embryo. During this week, the heart beats and the circulatory system begins to function. Although your embryo resembles a tadpole, the early spinal cord and nervous system are forming.

Your Body:

The developing baby is most sensitive to the adverse effects of alcohol, tobacco, radiation and a variety of medications from the fifth week until twenty weeks gestation. You may or may not be experiencing pregnancy symptoms at this point. Almost all women report fatigue at this time, and some report nausea, mood swings and breast sensitivity. Fortunately, nausea and fatigue usually improve after the first trimester. In the meantime, steer clear of foods that make you queasy but don’t skip meals. Get plenty of rest, it takes a lot of energy to provide your growing baby the perfect environment.

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Week 6

Your Baby:

About the size of a pea, the heartbeat is usually visible by ultrasound. Baby’s cheeks, chin, eyes, ears, and nose are beginning to form as well. The liver, kidneys and lungs are all developing. The crown-rump length (CRL), which measures the length of the embryo, can be used to accurately determine the gestational age at this time. The embryo is growing an average of 1mm in length daily!

Your Body:

Hormonal changes and increased blood flow to your growing uterus is now putting pressure on your bladder, causing you to urinate more frequently. Most practitioners prefer you schedule your first prenatal visit between your seventh and tenth week. Some things to expect:

• Physical (including a pelvic and breast exam)
• Pap smear (unless you have had one recently)
• Blood tests to determine blood count, blood type and Rh factor
• STD testing
• Ethnic dependent genetic test
• Urinalysis and culture

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Week 7

Your Baby:

Your baby is now the size of a blueberry (approximately a 1/4″). It’s mouth and tongue are forming. Small buds that will grow into your baby’s arms and legs appear this week. Brain cells are being formed at a rate of 100 cells per minute. The early amniotic sac can be seen by ultrasound.

Your Body:

Your baby is not the only one growing this week. Increased blood flow to your breasts and a build up of fat have most women moving up a cup size. This also explains those blue veins running across your chest. Take comfort in the fact your body is transporting the nutrients and fluids your baby will need after birth. This week you have developed a mucus plug that acts as a barrier in your cervix to protect from outside infection. You will lose this plug when your cervix dilates in preparation for labor.

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Week 8

Your Baby:

Your baby is about the size of a raspberry. At this point, even though you can’t feel it yet your baby is starting to move. Fingers and toes are beginning to form but are still webbed. Genitals are taking shape but it’s still much to early to determine gender by ultrasound. By the end of the eighth week, which is the final week of the embryonic period, the head comprises one half of the crown-rump length.

Your Body:

This week you may begin experiencing some pregnancy woes such as heartburn and constipation. Some tips, which may help, include eating smaller meals more frequently, avoiding acidic foods and heartburn triggers like coffee, tomato sauce, onions, peppers and garlic. To avoid constipation drink plenty of fluids and increase your fiber intake with fresh fruits and vegetables or ground flax seed.

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Week 9

Your Baby:

Your baby is about the size of a grape. At nine weeks the embryonic period has ended and the fetal period begins. All of the organs and body systems are now formed. The tip of the nose can be seen on an ultrasound and the eyelids are forming, defining your baby’s profile.

Your Body:

You may experience headaches, dizziness or lightheadedness due to hormonal and metabolic changes. This can trigger low blood sugar and while it’s not cause for concern it’s important to plan ahead. Pack light snacks to take with you in case you need a pick me up. Sit or lie down if you feel dizzy. If it happens frequently or you don’t feel better after a few minutes let your practitioner know. Newly developed blood tests, called Noninvasive Fetal Diagnostic Testing (NIFDT), are now available for several genetic disorders including Down syndrome as early as nine to ten weeks.

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Week 10

Your Baby:

Your baby is about the size of an olive and can flex and move their tiny but well defined extremities. The baby is swallowing amniotic fluid. The umbilical cord is transporting nutrients from your circulation to the fetus, which is now growing at an average of one to two millimeters every day.

Your Body:

Increased vaginal discharge is a result of more blood flow to the pelvic area in combination with an increase in estrogen production from your placenta. Usually it appears thin, milky white and is harmless. Another unwelcome occurrence as early as ten weeks is indigestion and gassiness. Try eating smaller meals and avoid foods that are known to exacerbate this symptom like beans, broccoli, fried foods and sweets. If you are having the genetic screening test CVS (chorionic villus sampling) it is usually done between now and 14 weeks.

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Week 11

Your Baby:

About two inches long and the size of a strawberry, your baby’s head still makes up half of the body length. Hair follicles are growing and tiny tooth buds are forming. The baby can now stretch and roll. If you are having a girl, the embryonic ovaries are developing. If you are having a boy, testosterone production is beginning.

Your Body:

Your uterus is about the size of a grapefruit this week and you may start to notice clothes fitting tighter. You are probably still feeling tired and run down but you are approaching the end of your first trimester and your energy level will begin to improve. The first trimester genetic screening is traditionally performed between 11 and 14 weeks. A blood test and/or ultrasound may be used to determine if your baby is at higher risk for certain chromosomal abnormalities like Down syndrome.

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Week 12

Your Baby:

Your baby weighs in at .5 ounces and 2.5 inches long, about the size of a plum. Fingernails and toenails are starting to form. Kidneys are functioning. Vocal chords are formed this week. Baby’s heartbeat is usually between 120 – 160 beats per minute. At this time, your baby’s heartbeat can be reliably detected with a doppler placed on your tummy in your practitioners office.

Your Body:

While many women enjoy a “pregnancy glow” that comes with increased blood volume resulting in a firmer, smoother skin appearance, other women experience acne due to increased oil gland secretion. Don’t worry it’s only temporary. That increased blood flow can also be responsible for nasal stuffiness, congestion, runny nose, dryness and even nose bleeds. Always consult your practitioner before using any available treatment.

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