Pregnancy

The First Trimester: What to Expect in the First Weeks of Pregnancy

Team Peanut2 days ago12 min read

Congratulations, and welcome to the first trimester of pregnancy!

First trimester

Whether this is all a surprise, or you’ve been working on it for years, getting that positive test result opens up a whole new world.

Big changes are coming!

So take a minute and breathe, mama.

We’ve got you covered.

Here’s your complete guide to the first trimester of pregnancy…

In this article 📝

  • How long is the first trimester of pregnancy?
  • Pregnancy first trimester symptoms
  • What is your baby doing in the first trimester?
  • What to do in first trimester
  • First trimester FAQs

How long is the first trimester of pregnancy?

So just how long is first trimester of pregnancy supposed to last?

The first trimester of pregnancy starts on the first day of your last period (yep, before you’re even pregnant!) and lasts up until the end of week 12 or 13 – depending on who you ask.

It’s a common misunderstanding when asking “how many weeks in first trimester?” to start from conception, but medical professionals will start from your last period.

Those initial first trimester weeks might feel as though they’re lasting forever while you’re waiting for your baby bump, but try to be patient.

Although you may feel pregnant, it’s unlikely you’ll look pregnant at this stage, so you can enjoy keeping your little secret a bit longer if you want to.

Pregnancy first trimester symptoms

While your baby gets used to their new home, you may, or may not, encounter some of these common first trimester symptoms.

Quick disclaimer: It can take a few weeks to feel any of these symptoms, so if you’re 3 weeks pregnant, no symptoms can be a totally normal part of your pregnancy.

Morning sickness

One of the most misleading names for anything, ever!

(In fact, we prefer the term “pregnancy nausea”, one of the new phrases in our Renaming Revolution.)

Morning sickness can strike at any time of day.

Thanks to all those new pregnancy hormones, up to 85% of expectant mamas will either feel nauseated or suffer from vomiting, or both, making pregnancy nausea one of the most common pregnancy first trimester symptoms.

Keeping some healthy snacks with you, like crackers or veggie sticks can help keep nausea at bay, and lots of mamas on Peanut swear by ginger or peppermint flavors or sweets or teas.

💡 Learn more: When Does Morning Sickness Start?

First-trimester insomnia

Along with ‘morning sickness’ in the first trimester, insomnia can be another of the more frustrating pregnancy first trimester symptoms.

Your body needs sleep to do all it needs to do so both you and baby can be healthy during pregnancy, so first-trimester insomnia can be exhausting (in more ways than one!).

Needing to pee more often, feeling nauseated, heartburn, and anxiety can all be causes of first-trimester insomnia, so try these tips to manage those potential causes:

  • Cut down on caffeine before bedtime
  • Regular exercise during the day
  • Meditation and deep breathing
  • Avoid foods that make you feel nauseated or give you heartburn
  • Stick to a bedtime routine
  • Try to stay away from your phone, TV, tablet, or computer around one hour before bedtime

Food cravings and aversions.

Your pre-pregnancy self loved some spicy Indian food, but now just the smell is enough to get you gagging.

Dreaming of salted chips all day?

Yup, it’s all thanks to that baby inside you!

In the first trimester of pregnancy, you’ll find that your tastes might change ‒ foods you used to love make you heave, and foods you used to hate have made their way into your daily snacks.

You might even find that your first trimester cravings are leading you to some weird and wonderful food combos, like french fries dipped into milkshake, or chocolate-covered pickles.

Try to maintain a balanced diet if you can, and just avoid the foods that make you feel gross for now.

Aversions and first trimester cravings are (thankfully) usually temporary.

Craving non-food items like laundry detergent, clay, or even dirt, though? This is a rare condition called Pica.

Research suggests Pica can be an indicator of anemia, so if you fancy munching on a bar of soap more than a bar of chocolate, please have a chat with your doctor!

💡 Learn more: When Do Pregnancy Cravings Start?

First-trimester cramps

Cramps during the first trimester of your pregnancy can be a perfectly normal sign of your uterine wall stretching, ready for baby’s growth.

But they can also be a sign of early pregnancy loss.

Typical first-trimester cramps (sometimes known as implantation cramps) are relatively mild, coming and going during the day and night ‒ similar to menstrual cramps or ovulation pain, which you can feel around your abdomen and perineum.

But if your cramps are more severe and out-of-the-ordinary for you (after all, ovulation and menstruation can feel different for each person), or accompanied by bleeding, it’s best to call your doctor, just in case.

If you’re concerned about your pregnancy, you can always reach out to your physician or doctor, or even to the other mamas and mamas-to-be on Peanut. We’re here for you.

Sore boobs

Before thinking of buying any baby clothes, you might need to check out a larger size bra for yourself.

Your breasts will naturally increase in size as they prepare to feed your baby and might be a bit sensitive for a while due to the surge in hormones.

You might go up a cup size or two within the first trimester, so finding the right supportive underwear will help you feel more comfortable.

First-trimester fatigue

Yep. You’re exhausted. All the time.

Your body is working hard and will produce almost 50% more blood to support the life growing inside you, so it’s not surprising you might be falling asleep on the sofa mid-Netflix binge!

To combat first-trimester fatigue, we suggest scheduling some naps and accepting any offers of help you can get.

💡 Learn more: Understanding Pregnancy Fatigue

Heartburn and constipation

Yet another attractive symptom of pregnancy…

Basically, the increase in your body’s level of progesterone slows muscle contraction which, in turn, slows down the passage of food waste through your bowels.

Say hello to constipation!

Progesterone also weakens the ring of muscle that usually separates the acids in your stomach from your esophagus, increasing the chance of heartburn.

Emotions in flux

In the space of a few minutes, you could be going from ecstatic to exhausted, peppy to petrified, crying tears of laughter to… well, just crying.

‘Mood swings’ are one of the more common pregnancy first trimester symptoms, and it’s all thanks to hormones.

First-trimester depression can also be a part of pregnancy ‒ according to the Mayo Clinic, around 7% of pregnant women experience depression during their pregnancy.

Remember: even if you are feeling a range of emotions in a short amount of time, these emotions are still valid. If you feel like you need to talk to someone, reach out to your partner, family member, friend, or even the mamas and mamas-to-be on Peanut.

Bleeding or discharge

You may notice some spotting and a milky-looking discharge, called leukorrhea, throughout the first trimester.

Both of these are normal, but if there’s any heavy bleeding or a discharge that’s yellow-green, seek medical advice.

Unfortunately, the first trimester is when women are most at risk of pregnancy loss.

If you have any heavy bleeding, severe abdominal cramps, sudden puffiness in your hands or face, fever, painful urination, or blurred vision, call your doctor immediately, or go to your nearest emergency department.

It may not be anything serious, but it’s always worth getting checked out.

It’s difficult to know if what you’re feeling is “normal” - especially if it’s your first pregnancy - but you know your body best.

When it comes to prenatal health, there’s no such thing as a silly question.

Frequent peeing

You might find that your visits to the bathroom are much more often during your first trimester of pregnancy.

This isn’t due to the size of your baby (they’re still a teeny tiny peanut at this stage), but instead due to your uterus growing, ready for baby to get bigger.

As it grows in size, your uterus puts pressure on your bladder, so you feel like you have to pee more frequently.

You should still drink plenty of water, though, but reducing your caffeine intake can help make those bathroom visits less frequent.

What is your baby doing in the first trimester?

It’s no wonder the first trimester of pregnancy might have you feeling a bit yuck, as this is the most rapid period of growth for your baby.

During these first 13 weeks, your baby will grow from a microscopic single cell to a peach-sized baby-like fetus. Pretty cool, huh?!

Weeks 0-4

Your baby grows to the size of a poppy seed (about 2mm)
You may not even know you’re pregnant at this point, because in the first 2 to 3 weeks, pregnant symptoms can easily be passed off as menstrual symptoms.

But there are lots going on already, with all your baby’s major organs beginning to form.

Amazingly, their own blood vessels have started developing, including the umbilical cord.

The optic nerves and lens of the eyes will start to develop around the 4-week mark too, so you can start imagining those baby blues staring adoringly up at you already.

Weeks 5-8

Your baby grows to the size of a raspberry (about 1.2cm)
During this period, your baby’s brain and spinal cord will develop, and the tiny little tube-shaped heart will start beating at around 6 weeks.

Limbs will have a “paddle” shape to them, and the head will start to look more, well, head-like, with indentations forming for the ears, nostrils, and lips.

Weeks 9-13

Your baby grows to the size of a lemon (about 8cm)
By this point, all the major systems and organs are formed, along with their limbs and even fingernails and toenails.

Their previously large head will be more in proportion with the rest of their body, and their face will have much more defined features.

Looking good, baby!

What to do in first trimester

There’s plenty to do to prepare for a baby, but here are our top tips for first trimester of pregnancy and your first-trimester checklist:

  • See your doctor, who will talk you through your pregnancy care options and what you need to do next. This may involve getting familiar with the healthcare system where you live, and arranging your first ultrasound. You’ll be sent for first-trimester screening blood and urine tests too, to rule out any early problems.
  • Start taking a prenatal vitamin if you’re not already. Your body needs extra help to support a growing, tiny human.
  • Avoid certain things like alcohol, cigarettes, vitamin A supplements, and caffeine. Try to steer clear of unpasteurized dairy foods, mold-ripened soft cheeses (like camembert and brie), sushi, paté, runny eggs, deli meats, and prepackaged salads, too, as they carry a higher risk of listeria and salmonella which can be dangerous for both you and baby.
  • Start a budget and take into consideration not only what you need to buy for the baby, but also any healthcare costs, insurance premiums, and changes to your household income.
  • Keep exercising, but avoid anything high-impact, like boxing or heavy weight-lifting. Adopting a prenatal fitness plan is a great idea to keep active throughout your pregnancy.

First trimester FAQs

What are good first-trimester workouts?

It’s best to check with your doctor which workouts and exercises you can do during your first trimester of pregnancy, as different people will have different fitness levels and tolerances.

But generally speaking, the following are good exercises and first-trimester workouts:

  • Yoga
  • Swimming
  • Walking
  • Cycling
  • Elliptical trainer or glider
  • Kegel exercises (aka pelvic floor exercises)
  • Low-intensity weight training

Just remember to stay hydrated, not put too much pressure on yourself, and listen to your body.

Can you have a massage when pregnant in first trimester?

According to the American Pregnancy Association, you can have a massage during the first trimester, but some massage therapists won’t do first-trimester massages.

This is due to the higher risk of loss early in pregnancy ‒ not that massages can cause pregnancy loss, but more that they wouldn’t want to be involved, should anything happen.

But prenatal massage can actually be beneficial to pregnant people, at any time during their pregnancy.

How much weight can a pregnant woman lift in the first trimester?

There’s no definitive answer to how much weight a pregnant woman can lift in the first trimester, since each pregnant person can have different tolerances, fitness levels, and strengths.

However, the American Pregnancy Association advises that you shouldn’t do any heavy lifting at any point during your pregnancy.

What you define as ‘heavy’ is totally up to you ‒ just don’t try to show off how much you can lift!

What not to do in first trimester

Here are some things to stop doing, or avoid altogether, during your first trimester of pregnancy:

Can you take Tylenol when pregnant first trimester?

Simply put, yes, you can take Tylenol when pregnant in your first trimester.

As long as you don’t exceed the maximum dose, and only take it when you need it ‒ for headaches, a fever, leg cramp ‒ there won’t be any risk to you or baby.

When do first trimester symptoms start?

Usually, you probably won’t feel any first-trimester symptoms until around week 6 of your pregnancy (remember, that’s 6 weeks from your last period, not 6 weeks from conception).

The first months and weeks of pregnancy are a whirlwind of emotions as you celebrate your news, adjust to your changing body, and mentally prepare for motherhood.

Remember that it’s okay to feel however it is that you feel - nervous, excited, and everything in between - it’s all perfectly normal. You’ve got this!

🤰 See next: The Second Trimester: Your Complete Guide