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Your first trimester guide to pregnancy

Your body will go through some amazing changes from trimester to trimester. It's all very exciting, but it also comes with its fair share of questions and anxieties. That's normal, mom-to-be. 

So to help set your mind at ease, we put together a guide to your more immediate future—the first trimester. Take a look at our answers to these common pregnancy questions. 

How was my due date determined?

Most providers figure out how many weeks pregnant you are by using the first day of your last menstrual period. That's because it's far easier for most women to remember when their last period was than to guess the precise time of conception. 

Want to know more? Read about how your due date is calculated here

When does the first trimester start and end? 

It starts with the first day of your last menstrual period and ends on the last day of the 13th week. That's months 1 through 3.

How often will I see my doctor this trimester?  

Most experts suggest that you see your provider about once a month during your first trimester.

If you're over 35 or your pregnancy is high risk, you'll likely see your doctor more often. During your visits, your provider will run a series of routine tests to ensure you and your baby are healthy. You can read more about common pregnancy tests here.  

When should I tell people that I'm pregnant?

That's your personal choice—there's no right or wrong time to spread the news. Some moms-to-be make an announcement as soon as a pregnancy test is positive. But because the risk of miscarriage is highest in the first trimester, others wait until they've reached their second trimester. Do what feels right for you. 

When will I start showing?

Every woman is different. By the end of your first trimester, a baby bump may be developing. That doesn't necessarily mean you have to switch to maternity clothes, though. But you'll probably need to swap tight-fitting clothes for looser, more forgiving ones. 

What should I be eating—or not eating? 

A healthy, well-balanced diet is best for both you and your baby. Focus on nutrient-packed foods from all five food groups: whole grains, all types of fruit, colorful veggies, lean protein and low-fat or fat-free dairy products. 

Cut back on sugary sodas, sweets and fried snacks. And don't eat fish with high levels of mercury, such as swordfish, king mackerel and tilefish. Mercury has been linked to birth defects. 

Discover more food dos and don'ts here

Is it safe for me to exercise? 

Yes, assuming you're heathy and your pregnancy is normal. And exercise isn't only safe—it's recommended because of its benefits. It may reduce your risk of pregnancy complications such as gestational diabetes and high blood pressure (aka pre-eclampsia). 

But play it safe and get a green light from your provider before hitting the gym. He or she may recommend that you make a few changes in how you work out. 

Get more tips on pregnancy-friendly workouts here

What symptoms can I expect? 

Hormonal changes in your first trimester can affect almost every system in your body. That means you may experience changes like these, even in the very first weeks of your pregnancy:

  • Tiredness and fatigue.
  • Tender, swollen breasts.
  • Upset stomach, with or without throwing up. 
  • Cravings for or aversions to certain foods.
  • Mood swings.
  • Constipation.
  • Need to urinate more often.
  • Headache.
  • Heartburn.
  • Weight gain or loss.

The good news: Most of these discomforts disappear on their own as your pregnancy progresses. And some women sail through their first trimester without any symptoms at all. But be sure to let your provider know if yours are severe. He or she may have some remedies to help make them better. 

More pregnancy news

Certain medications are also off limits when you're pregnant. Follow these tips  and talk to your provider about what medications are OK to take this trimester. 

Sources: Academy of Nutrition and Dietetics; American College of Obstetricians and Gynecologists; American Pregnancy Association; Office on Women's Health

Reviewed 12/6/2023

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