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Pregnancy Timeline - First Trimester Weeks 1 - 12

Updated: Dec 17, 2021

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What a bliss! You are pregnant. You become a mom the instance you find out you are pregnant!

Pregnancy is a time of mixed emotions. You are excited about your new arrival and anxious about everything parenthood entails. We know you want to soak up every second of this significant season in your life. As you prepare for your new chapter, we have broken down the important mile markers between finding out you are pregnant and holding your little one for the very first time "baby's "baby's "Let's start with the basics. Women often hear of the perils of nine long months of pregnancy, but did you know that doctors calculate pregnancy as ten months? When measuring pregnancy, it starts on the first day of your last menstrual period, even if it is a few weeks before conception. From that start date, most women usually carry full-term to 40 weeks. Those 40 weeks are divided into three trimesters of just over 13 weeks each. Each trimester is full of its special moments, markers, and milestones.

'Did you know that doctors calculate pregnancy as ten months? When measuring pregnancy, it starts on the first day of your last menstrual period, even if it is a few weeks before conception. Total 40 weeks!

First Trimester: Weeks 1 - 12


Weeks 1-2: You get pregnant in your first few weeks of pregnancy! Two weeks after your menstrual cycle, your body will ovulate. Your egg will travel down your fallopian tube and encounter sperm cells fertilizing it. The true mark of pregnancy is when this fertilized egg is attached to your uterine lining in a process called implantation.

Weeks 3-4: Every pregnancy is unique, but women can start seeing and sensing early signs of pregnancy between three and four weeks. While some women will not experience symptoms until later, you may notice fatigue, mood swings, bloating, nausea, tender or swollen breasts, frequent urination, and the most obvious sign – a missed period.

Your Next Steps: When you experience any of these symptoms, take a home pregnancy test. If the test is positive, then call your OBGyn. You can make an appointment to take another pregnancy test in their office for confirmation, or they may schedule you out for your first appointment around the eight-week mark. Either way, they can provide valuable insight on the following changes you need to make:

· Cut out ALL alcohol, smoking, and other similar substances!

· Start taking a prenatal vitamin with folic acid

· Check if your medications are safe to take while pregnant

· Avoid high-mercury foods such as tuna

· Limit your caffeine intake to 200 mg per day

· Avoid raw or unpasteurized foods


Weeks 5-6: Around Week 5, that fertilized egg and cluster of cells officially becomes an embryo. At this point, you may not be seeing much action, but know rapid changes are happening for your embryo. Internal organs are starting to develop. The neural tube that will later become the brain, spinal cord, and nerve system is forming. Even the umbilical cord is beginning to grow.

Weeks 7-8: While you may be frantically checking in the mirror and growing impatient waiting for some more signs of pregnancy, just know your righyourembryo'ssbryo'ssLet'syourembryo'ssbryo'ss heart, fingers, toes, ears, eyes, and upper lips are beginning to form. Some women cite that their symptoms from the first month carry over into the second. Also, it is common to experience some dizziness during the second month of pregnancy as you begin to carry more blood and your heart rate increases.

Your Next Steps: Your provider will schedule your first screening between 8 and 14 weeks. This screening includes an ultrasound to confirm pregnancy, estimate your due date, and check for a heartbeat, muscle tone, movement, multiple embryos, and overall development. This ultrasound will also be your first picture! Many women hang onto their ultrasound pictures as a keepsake and sometimes to announce their pregnancy to family and friends. Your provider will also draw your blood to screen for potential genetic conditions or congenital disabilities.


Weeks 9 -10: Your embryo graduates to a fetus at ten weeks. The umbilical cord will connect the fetus to your uterine wall and placenta. Sex organs also start to develop.

Weeks 11-12: As the fetus continues to grow into weeks 11 and 12, the bones will begin to harden, and they will start to develop skin, fingernails, and sweat glands. They also begin to become more mobile.

Your Next Steps: As you round out your first trimester, you may still be experiencing fatigue, nausea, breast tenderness, and bloating from the beginning of pregnancy. In fact, many women claim their symptoms worsen. You may also notice changes in your breasts and nipple and acne breakouts. You may be wondering, "when do I get the signature bump?". Despite popular belief, you do not put on much weight in your first trimester – keep in mind the baby is still very, very tiny! But, you have completed your first trimester and are stepping into your second. Most people wait to announce their pregnancy until their second trimester since most miscarriages occur in the first trimester.

When and how you tell people is entirely your choice. You can be as creative or use our announcement checklists blog for ideas.

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