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Your First Pregnancy Trimester: What to Expect

Your First Pregnancy Trimester: What to Expect

Congratulations! You're pregnant. Now what? If this is your first time, you may feel like you're venturing into uncharted territory as you enter the first trimester. Even if you have been pregnant before, your experience may be different this time around. Let’s review some of the changes you can expect in these early months.


Changing hormone levels, increased blood volume, stress and general fatigue can trigger headaches during the first trimester. Headaches can also be caused by caffeine withdrawal (if you’ve been a regular coffee drinker and stop once you get pregnant) or if you become dehydrated due to nausea and vomiting early in your pregnancy. Migraines are also more common during the first trimester of pregnancy – even if you’ve never been prone to them before. If any headache becomes severe, is accompanied by changes in vision, or just won’t go away, contact your doctor immediately.

To help avoid headaches, eat well and drink plenty of fluids. Avoid any known headache triggers or foods that may have caused headaches in the past. Avoid secondhand smoke (and of course never smoke yourself) and try to reduce stress with yoga, meditation, or some other calming practice. Aim to maintain a regular sleep schedule. If a headache does occur, try cold compresses and massage to ease the pain. Although most pain relievers should be avoided during pregnancy, many women can safely take acetaminophen for an occasional headache if necessary. However, never take any medication (even herbal remedies) without talking to your doctor first.

Vaginal Bleeding or Spotting

A lot happens to your body during pregnancy but the first sign you may be expecting is what doesn’t happen: getting your period. However, bleeding in early pregnancy is common. A small amount of bleeding may happen:

  • When the fertilized egg implants into the lining of uterus
  • As a result of normal cervical changes
  • After sex

While it is not usually a cause for concern, you should always call your doctor if you have bleeding at any time during pregnancy.

Breast changes

Shortly after conception, your body will start producing more of the hormones estrogen and progesterone. This stimulates growth of the mammary glands in preparation for breastfeeding. You may experience breast swelling, tenderness, and discomfort. A supportive bra will help you be more comfortable. Your areolas (the dark area around your nipples) will enlarge and darken. You may notice veins on the surface of your breasts.

Morning sickness

Showing a woman vomiting is cinematic shorthand for “she’s pregnant,” but the truth is, morning sickness varies greatly from one woman and one pregnancy to the next. Morning sickness usually begins four to nine weeks into a pregnancy. It can also strike at any time of the day or night. While up to 80% of moms-to-be experience some form of morning sickness, some women barely feel nauseous at all. An unlucky few – less than 3% – suffer from a form of extreme, persistent nausea and vomiting known as hyperemesis gravidarum.

Sometimes called severe morning sickness, hyperemesis gravidarum (HG) requires medical management. If you have regular morning sickness. You should be able to keep food and liquids down most of the time. It usually abates towards the end of the first trimester. With hyperemesis gravidarum, you may vomit several times per day. This can eventually lead to weight loss and dehydration. Symptoms of HG often last longer than morning sickness and a woman may become dehydrated enough to need IV fluids.

Frequent urination

Even in those early months, you may need to urinate more frequently. There are two reasons for this. Pregnancy increases the amount of blood in your body, causing your kidneys to process more fluid and make more urine. Meanwhile, your uterus is pressing on your bladder as it grows, and you can expect the bathroom trips to grow more frequent over time.


Constipation is a problem many pregnant people must deal with. Just as it presses on the bladder, the growing uterus applies pressure to the rectum and intestines. What’s more, motility, the natural muscular contraction of the intestines that pushes food through the digestive track, slows down due to high levels of progesterone. This can lead to heartburn, indigestion, constipation, and gas. To help relieve constipation, eat plenty of fiber-rich foods such as fresh or dried fruit, raw vegetables, and whole-grain cereals and bread. Drink lots of fluids, especially water and prune juice or other fruit juices and cut back your caffeine consumption. If you are really uncomfortable, ask your healthcare professional about stool softeners.


Pregnancy hormones have a negative impact on your tummy. Not only do they slow the digestion of food, but they relax the valve between your stomach and esophagus, making it easier for stomach acid to leak up into your esophagus (reflux) and causing heartburn.

To prevent heartburn:

  • Eat smaller, more frequent meals
  • Sip water between meals

  • Avoid fried, greasy, or spicy foods, chocolate, and citrus fruits
  • Stay vertical – don’t lie down after a meal and try not to eat or drink within a couple of hours before bed


This article appeared in the May 2024 edition of the HealthPerks newsletter.

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