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Your First Trimester of Pregnancy

It’s your first trimester – congratulations! This is a special and important time for new mothers. Learn about what to expect and how to prepare you, your baby and your growing family for what’s to come.

How Long is the First Trimester?

The first trimester begins on the first day of your last period and lasts until the end of week 12. Conception generally occurs about two weeks after your missed period.

A lot happens during these first three months. Not only is your body is going through a major transformation, but you also have a lot on your to-do list. First and foremost, take care of yourself! Eat healthily, drink plenty of water, rest and take your prenatal vitamins. 

What to Expect During the First Trimester

Although others likely won’t be able to tell you’re pregnant in the first trimester, you may notice differences with how you look and feel. Knowing what physical and emotional changes to expect can help you be more confident, informed and prepared for what comes next.

What’s Happening to Mom in the First Trimester

Hormonal changes start very soon after conception and affect nearly every part of a woman’s body. Pregnancy increases your amount of blood, making you urinate more often. Your progesterone level soars, causing fatigue and constipation. The valve between your stomach and esophagus relaxes, increasing heartburn. You may develop morning sickness and aversions to certain foods.

Hormones also affect your emotions. Pregnancy can make you feel happy, nervous and excited all at the same time. It can be overwhelming to worry about your baby's health, parenthood, finances and career. What you're feeling is normal. Lean on your support system for understanding and encouragement. Don’t be afraid to talk to your doctor if your feelings become abnormally difficult to manage.

The good news is, as hormone levels stabilize, some of your discomforts may ease. For many women, the first trimester is often the worst for fatigue, morning sickness and mood swings.

Signs and Symptoms of the First Trimester

Even before you take a pregnancy test, you might notice symptoms as hormones trigger your body to begin nourishing the baby. Common signs and symptoms of early pregnancy include:

  • Bleeding or spotting
  • Bloating
  • Constipation
  • Cramping
  • Darkening and bumpy areolas
  • Fatigue
  • Food aversions
  • Heartburn
  • Increased urination
  • Mood swings
  • Morning sickness or nausea
  • Raised basal body temperature
  • Smell sensitivity
  • Tender, swollen breasts

What’s Happening to Baby in the First Trimester

Your baby develops rapidly during the first trimester. The fetus starts to form a brain, spinal cord and organs. Her heart begins to beat. Sex organs form. Arms and legs bud followed by fingers and toes. Toward the end of the first trimester, she’s around 3 inches long and weighs almost 1 ounce.

First Trimester Prenatal Care

Contact your doctor if you think you are pregnant. If you are not already on prenatal vitamins, start taking them immediately.

At your first appointment, your doctor confirms your pregnancy, asks questions about your overall health and family history, performs a Pap test, checks your weight, collects urine and blood samples and determines your due date (baby's gestational age). They also talk to you about prenatal care, including how to care for yourself, testing and procedures and normal vs. abnormal symptoms.

During the first trimester, you have regular checkups every four weeks. During your appointments, be open and honest with your doctor. Discuss any concerns you have. Your doctor is here to help you take care of yourself and your baby.

Around 11 weeks, your doctor does a nuchal translucency (NT) scan. This is an ultrasound to measure the baby’s head and neck thickness to help determine the chance of a genetic disorder. Ask your doctor if genetic screening is recommended for your pregnancy, which can further assess your baby’s risk of specific genetic diseases.

Questions to ask your doctor:

  • How far along am I in my pregnancy?
  • What physical and emotional changes should I expect?
  • Are my symptoms normal?
  • Are there any risks that I should be aware of?
  • Are all my medications safe for pregnancy?
  • Who should I call if I have questions or concerns?
  • Is there anything I should change about my lifestyle?

First Trimester Checklist

  • Take a prenatal vitamin
  • Understand your health insurance
  • Choose a health care provider
  • Make a prenatal appointment
  • Make sure your medications are pregnancy-safe
  • Make sure your activities are pregnancy-safe
  • Learn about prenatal testing
  • Learn the signs of a pregnancy problem
  • Quit smoking
  • Stop drinking alcohol
  • Cut down on caffeine
  • Drink water
  • Eat a healthy balanced diet
  • Eat enough calories (about 300 calories more than normal)
  • Don’t eat unsafe foods like raw fish, deli meats and unpasteurized dairy
  • Sleep
  • Exercise
  • Stay away from cat litter, which can carry a parasitic disease called toxoplasmosis
  • Think about when and how to announce your pregnancy
  • Have sex (if you want)
  • Talk to your partner about parenting
  • Make a budget