What to Expect During Your First Trimester

Before anything else, we’d like to congratulate you on your pregnancy! This can be both an exciting and challenging life stage as you’ll experience various physical and hormonal changes while having unexplainable joy at the same time.

A normal pregnancy usually lasts about 40 weeks, separated into three trimesters. We’ve fleshed out some of the most common symptoms, tests and screenings you may experience during your first trimester and other information that can help you prepare in keeping you and your baby healthy throughout the journey.

When is the First Trimester of Pregnancy?

The first trimester is also called the embryonic stage. It occurs from week 1 to week 12 or the first three months of your pregnancy. Here are the things to watch for month by month during the first trimester:

1st Month: The Fetus Develops as You Experience Symptoms

In the first two weeks of the first trimester, your body secretes follicle-stimulating hormone (FSH) to stimulate the egg to mature. Also, your placenta starts forming and your uterus stretches to support the growth of the fetus and placenta. In the third week, implantation happens and the fetus begins to develop rapidly. At four weeks, the baby is already an embryo comprised of two layers of cells.

Your hormone levels change significantly; your breasts are swelling; your heart rate increases. You may experience mild cramping. When you visit your doctor for the first time, the doctor can most likely provide an estimate of your due date or date of delivery, which is around 266 days from the first day of your last period.

2nd Month: Your Baby’s Features Start to Show

From week 1 to 8, your baby’s unique shape and features start to form and develop. The brain, nervous system, spinal cord, digestive system, respiratory system, umbilical cord, arms and legs are showing and are expanding further. Your baby’s heart will start beating as well, which may also be detected when you have an ultrasound.

The most challenging pregnancy symptoms may hit full force during this period as your body adjusts to pregnancy necessities. These may include morning sickness or nausea, increased urination, heartburn, constipation, visible veins, skin changes, vaginal changes, fatigue, emotional symptoms and headache.

3rd Month: Your Baby Starts to Move

Babies usually measure about 0.6 to 0.7 inches and weigh around 0.1 ounces or 3 grams in the ninth week of pregnancy. Their head is a bit larger than the rest of their body and their tiny toenails and fingernails start to form. They also make their first movements as their muscles continue to develop, although you may not be able to feel them yet.

At week 11, your doctor may recommend a first-trimester screening which involves an ultrasound and a blood test to help determine if your baby is at an increased risk for a chromosomal abnormality or not. During the last week of the first trimester, people may start noticing your pregnancy glow.

Tests and Screenings You May Need in the First Trimester

Medical tests, screenings and check-ups are vital to keeping you and your baby healthy during pregnancy. This is called prenatal care. For the first trimester, your doctor may recommend the following tests and screenings:

  • Ultrasound
  • Pap test
  • Urine test
  • Blood sugar tests
  • Blood pressure checks
  • Tests for sexually transmitted infections, HIV and hepatitis
  • Screening for risk factors like anemia
  • Thyroid level checks
  • Nuchal translucency (NT) scan

Staying Healthy in Your First Trimester

Many pregnancy losses happen during the first trimester, so it’s crucial to keep in touch with your doctor. Staying healthy during this time is also vital to your developing baby, so be sure to take health measures such as:

  • Consuming a diet high in vegetables, fruits, protein, fiber and other nutrients
  • Drinking lots of water
  • Being physically active but not overdoing it
  • Taking prenatal vitamins and supplements as recommended by your OB-GYN

Also, to stay safe and healthy, please avoid:

  • Drinking alcohol
  • Smoking
  • Too much caffeine (not over a cup of coffee or tea per day)
  • Illegal drugs
  • Strenuous exercises or strength training that could cause an injury
  • Foods high in mercury, such as swordfish, mackerel, shark, etc.
  • Cat litter (may carry a parasitic disease called toxoplasmosis)
  • Unpasteurized milk
  • Processed food

Final Thoughts

Being pregnant can indeed be challenging, but it’s a beautiful journey like no other. Working closely with your doctor, especially during the first trimester, is crucial for your welfare and your baby, so we recommend that you keep all your appointments.

If you need help in paying for care, the good news is that there are options available for help, whether provided by the government or social service agencies, depending on your location. Some health insurances also offer more opportunities for prenatal care.

Office on Women’s Health
American Academy of Family Physicians

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