The first trimester can feel like a lot at once — exciting news, big changes, and often the most intense symptoms. Here’s a calm overview of what to expect in the early weeks.
What counts as the first trimester?
Pregnancy is divided into three trimesters. The first covers weeks 1 to 13 (remember, weeks are counted from your last period, so the first couple of “weeks” are before conception).
First trimester
Early development; many feel tired or queasy.
Second trimester
The “easier” middle; first kicks and the anatomy scan.
Third trimester
Baby grows quickly; you prepare for birth.
Not sure how far along you are? How pregnancy weeks are counted explains the maths behind the dates.
What’s your baby doing in the first trimester?
A surprising amount happens fast. By around 6 weeks a tiny heartbeat can often be detected on an early scan. Through weeks 6–10 the major organs, brain and limbs begin to form, and by the end of week 10 your baby is officially a fetus rather than an embryo. By the close of the first trimester — around week 13 — your baby is roughly the size of a plum, with tiny fingers, toes and a developing face, even though you won’t feel movement for several more weeks. This rapid early building is also part of why fatigue and nausea hit hardest now: your body is doing extraordinary work behind the scenes, growing a whole new organ — the placenta — at the same time.
Common first-trimester symptoms
This is when hormone levels rise fastest, so symptoms are often strongest. You might notice:
- Fatigue — a deep tiredness is one of the most common early signs.
- Nausea (“morning” sickness) — which can strike any time of day, often easing by weeks 12–14.
- Tender, changing breasts.
- Needing to pee more, food aversions, a heightened sense of smell, and mood changes.
Symptoms vary hugely. Feeling very unwell and feeling barely any different are both normal — see early signs of pregnancy for more.
Here’s what’s behind the most common ones — and small things that can help:
| Symptom | Why it happens | What can help |
|---|---|---|
| Fatigue | Rising progesterone; your body is working hard | Rest when you can; short naps; early nights |
| Nausea | Rapidly rising hCG | Small, frequent snacks; ginger; eating before you feel hungry |
| Sore breasts | Hormonal changes preparing for milk | A soft, supportive bra |
| Frequent peeing | Hormones and increased blood flow | Normal — keep hydrating anyway |
If you can’t keep any food or fluids down, or you’re losing weight, that’s worth flagging to your provider — occasionally nausea needs extra support.
Key milestones
- Your first prenatal appointment, usually in the first trimester, where you’ll discuss health history and next steps.
- A dating scan, typically offered between 8 and 14 weeks, confirming how far along you are and your due date.
- Early screening, which may be offered around 11–14 weeks — your provider will explain your options.
- The end of week 13, when many people start to feel more energetic as the second trimester approaches.
What’s safe in the first trimester?
A few simple habits cover most of it:
- Take a daily prenatal vitamin with folic acid (around 400 mcg), ideally from before conception through the first trimester.
- Skip alcohol and smoking, and check any regular medications or supplements with your provider.
- Avoid higher-risk foods — high-mercury fish, unpasteurised cheese and milk, and raw or undercooked meat, fish and eggs.
- Limit caffeine to a moderate amount (many guidelines suggest under about 200 mg a day, roughly one to two cups of coffee).
- Keep moving gently — most low-impact exercise is encouraged in a healthy pregnancy, but check with your provider about your situation.
When in doubt about anything specific, your midwife or doctor is the right person to ask — guidance can vary by country and by your own history.
Looking after yourself
In these early weeks, gentle self-care goes a long way:
- Rest when you can — fatigue is real; listen to your body.
- Eat what stays down. If nausea makes eating hard, small, frequent snacks often help.
- Stay hydrated and follow your provider’s advice on prenatal vitamins.
- Go easy on yourself emotionally. Early pregnancy can be a swirl of feelings; that’s normal.
- Don’t worry about “eating for two.” Your calorie needs barely change in the first trimester — focus on eating regularly and what you can tolerate, not on eating more.
It’s also entirely your choice when to share your news. Many people wait until after the dating scan, others tell a trusted few early for support during the queasy, tiring weeks — there’s no right answer, only what feels comfortable for you.
When should you call your provider?
Most early-pregnancy symptoms are normal, but some are worth checking promptly. Contact your provider if you have:
- Heavy bleeding, or bleeding with cramping.
- Severe or one-sided abdominal pain.
- A high fever, or feeling very unwell.
- Severe vomiting that stops you keeping fluids down.
Reaching out doesn’t mean overreacting — early pregnancy is exactly when it’s wise to ask, and your care team would always rather hear from you than have you worry alone at home.
What’s next
As you move toward the second trimester, many find symptoms ease and energy returns. Follow your week-by-week journey with the Pregnancy Week Tracker, which shows what’s developing and how far along you are at a glance.
This article is for general information only and isn’t medical advice. Your healthcare provider is the best source for questions about your pregnancy.