1st Trimester Pregnancy Guide: Symptoms, Tests & What to Expect

The first trimester of pregnancy can be both amazing and overwhelming. While your heart is full of joy at the thought of your little one arriving, your body is adjusting to a tidal wave of hormonal and physical changes that can leave you feeling tired and emotional.

For most first-time mums, these changes can be confusing, and not knowing what to expect only adds to the stress.

This blog will walk you through it all, with weekly changes in your body, nutrition tips, and early pregnancy tests to take and signs to look out for!

What is the First Trimester?

The first trimester of pregnancy is the period from conception to the end of the 12th week. Immediately after conception (the process of fertilization, where a sperm cell unites with an egg cell, marking the beginning of pregnancy), the body starts preparing to nurture and grow a new life.¹

The preparation includes thickening of the uterine lining to support implantation, increasing blood flow to the uterus and producing hormones like hCG, estrogen and progesterone to help with the pregnancy. This increase in pregnancy hormone levels often causes first trimester symptoms like nausea, fatigue, mood swings and breast tenderness. Some women pass through these early weeks with minimal discomfort, while others may experience severe nausea and food aversions.

Your baby, just an embryo at this stage, undergoes rapid development. Almost all the major organs of the embryo are developed by the end of the first trimester and the embryo becomes a fetus. This stage lays the foundation for the baby’s growth in the upcoming months. 

Understanding what to expect during the first trimester of pregnancy can help you feel more prepared and less anxious. Coming up next are the first trimester symptoms.

Common First Trimester Symptoms

You may undergo a lot of changes in your body at the onset of the first trimester. Here are some of the most common symptoms women experience during this time: 2, 3

1. Nausea and Vomiting (Morning Sickness):

Often starting around the 6th week of pregnancy, nausea and vomiting can occur at any time of the day. It is triggered by hormonal changes, especially the rise in hCG levels. 

Fun Fact: The term ‘morning sickness’ is actually a misnomer as nausea can occur at any time of the day, not just in the morning. However, it originated from the fact that nausea during pregnancy is more severe in the morning. It is now accurately referred to as NVP- nausea and vomiting during pregnancy. ⁴

2. Tiredness:

The rise in progesterone levels makes the body more tired. Feeling tired and needing more rest is common as your body is working overtime to nurture the pregnancy. 

3. Tenderness in the Breast:

Breasts usually feel tender and swollen during the first trimester because of hormonal changes. The body prepares the breasts for lactation and hence, they feel more sensitive than usual.

4. Frequent Urination:

Pressure from the growing size of the uterus and increased blood flow to the kidneys makes you feel the urge to pee more often. 

5. Mood Swings:

Hormonal fluctuations can make you more emotional, irritable or moody.

6. Food Aversions or Cravings:

You may suddenly dislike certain foods or develop strong cravings, often due to hormonal changes affecting your sense of taste and smell.

7. Bloating and Gas:

Slowed digestion due to increased progesterone can cause bloating, gas and discomfort.

8. Mild Cramping and Spotting: 

Light cramping or spotting is normal in early pregnancy as the embryo implants in the uterus, but anything heavy or painful should be discussed with your doctor.

9. Constipation:

The digestive system slows down because of the pregnancy hormones, often leading to constipation.

10. Dizziness or Lightheadedness: 

Lower blood pressure and changes in circulation can make you feel faint or dizzy, especially when standing up quickly.

All the above-mentioned first trimester symptoms are quite normal. However, it is recommended to visit your doctor if you feel anything unusual or severe, like heavy bleeding or intense pain.

Key Tests & Screenings in the First Trimester

Your doctor may have provided you with a list of first trimester tests to ensure the safety and healthy development of your baby. ⁵

Some of the key early pregnancy tests are:

Routine Blood Tests

• Complete Blood Count (CBC): To check for anemia, infections and overall blood health.
• Glucose Screening: To check for gestational or pre-existing diabetes.
• Thyroid Function Test: To analyse thyroid hormone levels, essential for fetal brain development.
• Blood Type and Rh Factor: To determine your blood group and Rh compatibility with the baby.
• Infection Screening: Early screening for infections is done to prevent transmission to the baby and to manage them better at the initial stage itself.

2. Urine Tests

• Urine Culture: To check for any asymptomatic urinary tract infections (UTIs).
• Urinalysis: To detect protein, glucose or any infections in the urine.

3. Ultrasound Scans

• Dating Scan: This is usually done in the initial 6 to 9 weeks to confirm the pregnancy, check for a heartbeat and estimate the due date of the baby’s arrival.
• Nuchal Translucency (NT) Scan: This test is done between 11 to 13 weeks to measure fluid at the back of the baby’s neck to assess the risk of chromosomal abnormalities like Down Syndrome.

4. Prenatal Screening Tests

Non-Invasive Prenatal Testing (NIPT) (optional but highly accurate): This blood test checks for genetic conditions like Down syndrome from fetal DNA in the mother’s blood.

What to Expect Week-by-Week

Here is a detailed breakdown of what changes take place in your body week-by-week during the first trimester of pregnancy:

• Weeks 1–2: Preconception & Ovulation

Technically, you are not pregnant yet! You conceive during this time. Doctors count pregnancy from the first day of your last menstrual period (LMP). By the end of the second week, that is, after 14 days from your LMP, ovulation takes place. Fertilization occurs if sperm meets egg at this time. It is not possible to know the exact time of conception. 

• Week 3: Fertilization

The fertilized egg is called a zygote. As soon as it is fertilized, it begins dividing. Although the female will not notice any symptoms yet, the conception has taken place. The zygote quickly travels down the fallopian tubes and begins implanting itself in the uterus. 

• Week 4: Implantation

As the zygote implants in the uterus and begins dividing, it is called an embryo. Light spotting may occur during this time because of implantation bleeding. The period cycle is missed during this time. Furthermore, it’s also the time when placenta begins to form to nurture the growing embryo.

• Week 5: Baby is as Big as a Sesame Seed

You may now notice changes in your body, known as early pregnancy symptoms. Fatigue, tender breasts and nausea may start. The heart and circulatory system begin to form in the embryo. 

• Week 6: Heartbeat Begins

Morning sickness begins at this stage. You may feel bloating or mood swings. The heart starts beating and the facial features begin to develop. 

• Week 7: Brain & Limb Buds Develop

You may experience food aversions and frequent urination at this phase. The  baby’s brain development accelerates and the arms and legs just begin to develop.

• Week 8: Fingers & Facial Features Develop

By the 8th week, your breasts may become fuller, and you may experience more mood swings. The facial features of the zygote become more defined. The fingers and toes also start to develop.

• Week 9: Tiny Movements

Nausea may be at its peak during the 9th week. You may feel a strong aversion to certain smells. The embryo begins to make small movements, although you may not be able to feel them yet.

• Week 10: Embryo Becomes a Fetus

By the 10th week, the embryo is the size of a prune and is now called a fetus. Your waistline may begin to expand during this phase. You may get relief from some of the earlier symptoms like nausea.

• Week 11: Growing Rapidly

You may experience rapid changes in your body. You may also get acne breakouts due to hormonal changes. The bones of the fetus begin to harden and the genitals begin forming.

• Week 12: End of First Trimester

The first trimester ends by the end of the 12th week. You may feel more energetic and the risk of miscarriage drops. The fetus develops reflexes, and the face takes a more human form. The fetus is now the size of a lime. 

When to See a Doctor Urgently

While many symptoms are normal in early pregnancy, certain signs should never be ignored. Here is a list of signs that should ring warning bells in your mind immediately. You should call your doctor or go see them if you experience any of these signs:

• Heavy Bleeding or Passing Clots

Light spotting may be normal but heavy bleeding may signal a miscarriage or other complications. 

Severe Pelvic or Abdominal Pain

A sharp or intense pain in the pelvic or abdominal area, especially on one side, can indicate an ectopic pregnancy.⁶

• Severe Dizziness or Fainting

Occasional dizziness is common, but fainting may suggest low blood pressure. You may need immediate medical assistance.

• Painful or Burning Urination

This may indicate a urinary tract infection, which may be risky during pregnancy if left untreated.

• High Fever (Above 100.4°F or 38°C)

A persistent high fever might indicate an infection that needs immediate medical assistance. 

• Persistent Vomiting

This could lead to dehydration and must be monitored or stopped. You may require treatment for hyperemesis gravidarum (a severe form of nausea and vomiting during pregnancy that can lead to dehydration and weight loss).

• Sudden Swelling of Feet, Hands or Face

This could indicate blood pressure issues and should be checked with a doctor.

• Unusual Vaginal Discharge Accompanied with Itching

An unusual vaginal discharge may indicate a sign of an infection that should be treated.

• Zero Pregnancy Symptoms after Testing Positive

If the symptoms suddenly disappear or do not appear at all, you need to check with your doctor. It could be a sign of a terminated pregnancy.

Final Take Away

A healthy first trimester of pregnancy lays the foundation for the well-being of both mother and baby in the coming months. So if you’re expecting, take your medications regularly, eat well, rest, sleep adequately and do not hesitate to ask for help. Furthermore, do not miss your doctor’s visits to ensure all is well with you and the baby. 

To support your journey further, consider the First Trimester Quadruple Delfia Test by LifeCell Diagnostics. This advanced screening helps assess the risk of chromosomal abnormalities in the developing baby early on, giving you peace of mind and allowing timely medical guidance if needed.

FAQs

What to avoid in the 1st trimester of pregnancy?

It is advised to avoid smoking, alcohol and recreational drugs completely during the first trimester of pregnancy. You should limit caffeine intake to under 200 mg per day. Raw or uncooked meat, unpasteurized dairy products and high-mercury fish like king mackerel or swordfish are not recommended. It is also advised to avoid heavy weight lifting, excessive heat exposure and self-medication during this period.

Can I travel during the first trimester?

Yes, you can travel during the first trimester if your pregnancy is low-risk. However, you should always discuss with your doctor before making travel plans during pregnancy.