When Does the Second Trimester Start? Pregnancy Timeline, Milestones & Full-Term Dates

If you're wondering when the second trimester starts, the short answer is: the second trimester typically begins at 14 weeks 0 days of pregnancy.

That means the first trimester ends at 13 weeks 6 days, and the second trimester continues until 27 weeks 6 days. Then the third trimester begins at 28 weeks 0 days.

For many expecting parents, this part of pregnancy feels like a big turning point. Morning sickness may start easing, energy may improve, and major milestones like the anatomy scan begin to get closer. But even though these definitions are standard, many people still want to know:

• When exactly does the second trimester start for my pregnancy?
• When is the anatomy scan usually scheduled?
• When does the third trimester begin?
• What does "full term" actually mean?
• How can I see all my milestone dates in one place?

🤰 Want your exact trimester and milestone dates? Try our Pregnancy Milestone Calculator →

The short answer: when does the second trimester start?

The second trimester starts at 14 weeks 0 days.

Here's the standard breakdown:

• First trimester: Week 1 through 13 weeks 6 days
• Second trimester: 14 weeks 0 days through 27 weeks 6 days
• Third trimester: starts at 28 weeks 0 days

These are the standard clinical definitions most pregnancy resources use. Your doctor or midwife may sometimes talk more generally in terms of "around 14 weeks" or "around 28 weeks," but these are the usual cutoffs.

Pregnancy trimester timeline at a glance

Here's a simple pregnancy milestone chart:

Pregnancy Stage	Starts	Ends
First Trimester	Week 1	13 weeks 6 days
Second Trimester	14 weeks 0 days	27 weeks 6 days
Third Trimester	28 weeks 0 days	Birth
Full Term Window	39 weeks 0 days	40 weeks 6 days
Estimated Due Date	40 weeks 0 days	—

📅 Know your due date, weeks pregnant, or LMP? Get your personalized pregnancy milestone dates in seconds →

Why the second trimester matters

The second trimester is often the stage people look forward to most. For many, it brings some physical relief and more visible signs of pregnancy.

Common reasons this trimester feels important include:

• nausea and fatigue may improve
• your baby bump may become more noticeable
• the anatomy scan is usually scheduled during this period
• movement may start to become more noticeable
• pregnancy planning starts to feel more real

This is also when many parents begin preparing for baby gear, nursery plans, maternity photos, travel cutoffs, and childbirth classes.

What happens at 14 weeks pregnant?

At 14 weeks, you're officially in the second trimester. Even though every pregnancy is different, this is commonly when:

• first-trimester symptoms may begin to ease
• appetite may improve
• energy may start coming back
• prenatal appointments continue on a regular schedule
• future screening and ultrasound milestones become more relevant

Emotionally, this stage can also feel reassuring because you're moving past the earliest phase of pregnancy.

When does the third trimester start?

The third trimester starts at 28 weeks 0 days.

This is the final major stage of pregnancy. During this time, your baby gains more weight, prenatal visits may become more frequent, and birth preparation usually becomes more concrete.

Many people start focusing on:

• labor and delivery planning
• pediatrician selection
• hospital bag packing
• newborn essentials
• final prenatal checklists

If you want a timeline that shows both the second trimester and third trimester start dates in one place, that's exactly the kind of thing a milestone calculator helps simplify.

When is the anatomy scan usually done?

The anatomy scan is typically done between 18 and 22 weeks of pregnancy.

This ultrasound is sometimes called:

• the 20-week scan
• the mid-pregnancy ultrasound
• the anatomy ultrasound

It's one of the most anticipated pregnancy milestones because it's a more detailed look at fetal development. Your provider may assess growth, major organs, anatomy, and placenta position. The exact timing depends on your provider and your care plan, but the standard window is 18 to 22 weeks.

That's one reason many parents search for a week-by-week pregnancy timeline — they want to know how close they are to the next big appointment.

What does full term mean in pregnancy?

A pregnancy is considered full term from 39 weeks 0 days through 40 weeks 6 days.

This surprises a lot of people because many assume the due date itself is the only "full term" date. In reality, the due date sits inside the full-term window.

Here's how the later weeks are commonly described:

Term	Gestational Age
Early term	37 weeks 0 days – 38 weeks 6 days
Full term	39 weeks 0 days – 40 weeks 6 days
Late term	41 weeks 0 days – 41 weeks 6 days
Post-term	42 weeks 0 days and beyond

Understanding this helps parents put the due date in context. Very few babies arrive on the exact estimated due date, so seeing the broader timing window can make pregnancy planning feel more realistic.

What is the "hospital bag ready" date?

A lot of parents like to use 37 weeks as a practical "go bag ready" milestone.

This is not a medical deadline, but it's a useful planning target. By 37 weeks, pregnancy is considered early term, and since labor timing is unpredictable, many people feel more comfortable having their essentials packed by then.

That can include:

• ID and insurance card
• comfortable clothes
• toiletries
• baby outfit
• charger
• postpartum items
• any provider-recommended paperwork

This "ready-by" date works especially well in a pregnancy milestone calculator because it turns a vague task into a clear planning date.

How pregnancy milestone calculators work

A Pregnancy Milestone Calculator estimates major dates using the standard 280-day pregnancy model, which is based on 40 weeks from the first day of your last menstrual period.

Most tools allow you to enter one of three starting points:

1. Due date

If you already know your estimated due date, the calculator works backward to estimate milestone dates like:

• second trimester start
• anatomy scan window
• third trimester start
• full-term window

2. Gestational age

If you know how many weeks pregnant you are right now, the tool estimates your due date first, then maps the rest of the pregnancy milestones.

3. Last menstrual period (LMP)

If you know the first day of your last period, the calculator adds 280 days to estimate the due date and then calculates all milestone dates from there.

This makes it easy to get a personalized view of your timeline without doing manual date counting.

Example pregnancy timeline

Let's say someone has an estimated due date of October 8.

Their pregnancy timeline would look roughly like this:

Milestone	Estimated Date
First trimester ends	April 8
Second trimester begins	April 9
Anatomy scan window	May 7 – June 4
Third trimester begins	July 16
Go bag ready-by date	September 17
Full term window	October 1 – October 14
Estimated due date	October 8

This kind of milestone map helps make the pregnancy journey feel much easier to understand.

Want your exact pregnancy milestone dates?

If you know your due date, weeks pregnant, or last menstrual period, you can calculate your estimated:

• ✅ Second trimester start date
• ✅ Anatomy scan window
• ✅ Third trimester start
• ✅ Full-term window
• ✅ Due date
• ✅ Suggested hospital bag ready-by date

🗓️ See your anatomy scan window, third trimester start, full-term dates, and due date in one place →

FAQ

Does the second trimester start at 13 or 14 weeks?

The standard definition is that the second trimester begins at 14 weeks 0 days. Since the first trimester ends at 13 weeks 6 days, the next day marks the start of trimester two.

What week is the anatomy scan?

It's usually scheduled between 18 and 22 weeks of pregnancy.

Is 37 weeks full term?

No. 37 weeks is considered early term, not full term. Full term begins at 39 weeks 0 days.

Is the due date the same as full term?

Not exactly. The due date is usually 40 weeks 0 days, which falls within the full-term range of 39 weeks 0 days to 40 weeks 6 days.

Can my due date change?

Yes. Early ultrasound dating may lead your provider to adjust your due date if it differs meaningfully from LMP-based dating.

What is the third trimester?

The third trimester is the final stage of pregnancy, starting at 28 weeks 0 days and continuing until birth. It's when your baby gains the most weight and birth preparation becomes more active.

How do I calculate my pregnancy milestones?

Enter your due date, current gestational age, or last menstrual period into a Pregnancy Milestone Calculator. It uses the standard 280-day model to estimate all your key dates instantly.

Final thoughts

If you've been wondering when the second trimester starts, the answer is simple: 14 weeks 0 days. But most parents want more than one milestone — they want the whole timeline.

That includes:

• when the first trimester ends
• when the anatomy scan happens
• when the third trimester starts
• when pregnancy becomes full term
• when to have the hospital bag packed

A personalized timeline makes all of that easier.

Use the Pregnancy Milestone Calculator → to estimate your exact dates and see where you are in your pregnancy journey.