First Trimester: Conception to 12 Weeks

Your Body, Your Baby


Your body and baby will progress through pregnancy on a developmental timeline or pregnancy calendar that tracks important milestones each week. Your pregnancy is counted in weeks and the “due date” is an estimated calendar date for the birth of your baby.

The first trimester of pregnancy actually begins at the start of your last menstrual period and lasts for approximately 12 weeks, even though conception occurs 10-14 days after the start of your last menstrual period.

Appointments and Tests

Most women have their first prenatal care appointment during the first trimester. Your health-care provider will review your health history, perform a physical exam and order specific blood and urine tests. Screening tests for genetic conditions may be necessary depending on your (the baby’s parents’) ethnic background. Your age may also be a factor that impacts the health of your baby, so you may need to have specific maternal screening tests.


Symptoms may not be noticeable right away during the first trimester but in 4-6 weeks of pregnancy you may experience breast tenderness, fatigue, frequent urination and constipation.

Nausea and vomiting (sometimes called morning sickness, although it can happen at any time of day) is very common and may start right away or develop sometime around the 9th week of pregnancy. The cause is not well known but it can last into your second trimester.

To help reduce nausea and vomiting consider:

  • Eating frequent, small meals throughout the day
  • Avoiding “trigger” foods with spice or strong odor
  • Including high protein snacks and peanut butter in your diet

In addition, you may want to talk to your health-care provider about:

  • Taking ginger capsules or Vitamin B6
  • Using pressure or electrical stimulation on the inside of your wrist (motion sickness bands or prescription devices)

Talk to your health-care provider about your symptoms. It’s not likely that your baby will be affected, but if you can’t keep fluids down or if you experience severe symptoms for more than 24 hours, notify your health-care provider immediately.

Taking Care of Yourself

You are going through many changes. Taking care of yourself and managing good prenatal care is very important.  Eat well, take daily prenatal vitamins and increase your fluid intake. And, when it comes to diet and exercise, consider these tips to help you and your baby:


Maintaining a healthy diet during pregnancy is achievable by eating foods that are rich in nutrients like calcium, iron, folate and protein. Some suggestions:

  • Calcium-rich foods: dairy products, tofu, green leafy vegetables
  • Iron-rich foods: meat, spinach, dry beans, fortified breads, dried fruit
  • Folate-rich foods: oranges, broccoli, asparagus, sunflower seeds
  • Protein-rich foods: meat, fish, poultry, lentils and nuts

Tips for You and Things to Avoid

  • Wash your hands before eating and after touching raw meat, fish or poultry
  • Clean countertops with hot, soapy water and wipe up food spills immediately
  • Cook food to safe internal temperatures
  • Avoid eating hot dogs, lunch/deli meats (unless reheated to steaming temperature)
  • Avoid drinks and foods with raw or unpasteurized milk; soft cheeses
  • Limit fish intake to 2 servings each week or approximately 12 oz.


Moderate exercise is safe for all healthy pregnant women and may provide some benefits. Before you begin review your exercise routines with your health-care provider, especially if you have a high-risk pregnancy.

Tips When Exercising:

  • Stay hydrated
  • Do not become overheated
  • Do the “talk test” – you should be able to talk through the exercise without feeling short of breath
  • Avoid activities that make it challenging to get oxygen like mountain climbing or scuba diving
  • Avoid activities that carry the risk of falling or injury to the abdomen like skiing and horseback riding
  • Contact your health-care provider immediately if you have severe pain or vaginal bleeding during exercise

Protecting You and Your Baby

For a healthy pregnancy that protects you and your baby from harm, consider these recommendations:

  • Drink lots of water – enough to so that your urine is light in color
  • Avoid alcohol, tobacco, drugs and use of herbs or natural supplements that are not approved by your health-care provider
  • Limit caffeine to 1-2 small cups of coffee or a 12-ounce soda
  • Avoid changing or cleaning the kitty litter box. Have someone else take care of it, if possible! If you have to, be sure to wear gloves and wash hands
  • Get your flu shot and other immunizations recommended by your health-care provider