Second Trimester Guide: Weeks 13 to 27

The second trimester runs from week 13 to the end of week 27. For most women this is the steadiest stretch of pregnancy. Nausea usually eases, energy often returns somewhere between week 13 and week 16, and your appetite comes back. Two appointments anchor the middle of pregnancy. The anatomy scan is commonly scheduled between weeks 18 and 22, and screening for gestational diabetes usually happens between weeks 24 and 28.¹ Nutritionally this is the stretch where building takes over from surviving, which means choline, calcium, magnesium and folate all matter more than they did a month ago.

What nobody told me was that the calm of the second trimester is when things quietly slip. You feel better, so you stop paying attention. You stop reading the label on the prenatal you grabbed in a panic at week five. You assume someone will tell you when the next appointment is due.

This is the guide I wanted at week 13. What happens, when it happens, what to ask for, and what your body is actually asking you to eat.

What happens in the second trimester?

The second trimester is weeks 13 through 27, roughly months four, five and six. It is often called the honeymoon trimester, which is a slightly annoying name if yours has not felt like one, but it points at something real. Early pregnancy symptoms tend to settle. The bump becomes visible. Most women start sleeping better before the third trimester takes that back.

Underneath the calm, a lot is happening. Your baby's skeleton is hardening. The brain is developing quickly. Your own blood volume keeps climbing to supply all of it. Almost every nutritional shift in this trimester traces back to one of those three things.

Second trimester timeline, weeks 13 to 27

Week 13. The second trimester begins. Nausea often starts to ease.
Weeks 14 to 16. Energy commonly returns. Appetite comes back with it.
Weeks 16 to 20. Many women feel the first movements, earlier if this is not a first pregnancy.
Weeks 18 to 22. The anatomy scan. A detailed ultrasound that checks growth and development.
Week 20. Halfway.
Weeks 24 to 28. Screening for gestational diabetes, usually a glucose drink and a blood draw.¹
Week 27. The last week of the second trimester.

Your own schedule may differ. Practices vary, and if you have a reason to be monitored more closely you will see more of your provider than this list suggests. Use this as a guide, not a rule.

Your second trimester checklist

This is the list I would print. Most of it is admin that gets harder the longer you leave it, and a few items are things people genuinely forget to ask for.

Book the anatomy scan and put it in your calendar the day you book it.
Ask when your glucose screening is scheduled.
Ask whether your iron levels have been checked, and when they will be checked again.
Keep taking your prenatal every single day, with a meal.
Read the label on the prenatal you are actually taking.
Start sleeping on your side.
Book a dental cleaning. Gums get more sensitive in pregnancy and this is the easy window.
Tell your employer if you have not already, and ask about leave paperwork.
Move most days, in whatever way your provider has cleared for you.
Start the registry before the third trimester tiredness arrives.
Book prenatal classes. Good ones fill months ahead.
Take the bump photos. You will want them.

What appointments happen in the second trimester?

The anatomy scan

Commonly scheduled between weeks 18 and 22, this is the long ultrasound. It checks your baby's growth and looks in detail at the developing organs, spine and limbs. It is also usually when you can find out the sex if you want to.

Bring your questions to this one. It tends to be the longest appointment you get in the whole middle stretch, and the sonographer is often the person with the most time to talk.

The glucose screening test

Gestational diabetes usually develops around the 24th week of pregnancy, and most women are tested between 24 and 28 weeks.¹ You drink a measured glucose solution and have blood drawn an hour later. If that first result is high you will be asked back for a longer test, which is common and not a diagnosis on its own.

Nobody enjoys the drink. Eat normally in the days beforehand rather than trying to game it, because the point of the test is to see how your body handles glucose in ordinary conditions.

The labs worth asking about

Blood volume rises substantially through pregnancy, and iron is the nutrient that conversation keeps landing on. Ask your provider whether your iron has been tested, what the result was, and when it will be rechecked.

If you want to see your numbers rather than wait to be told them, we partnered with Vanguard Performance Labs so Mothersense readers can order their own blood panels at a discounted rate. Take whatever comes back to your provider and go through it together. Ordering a panel is not a substitute for prenatal care, it just means you walk in with the numbers already in hand.

This is the reason we left iron out of our formula. Iron is one of the few nutrients in a prenatal where more is not automatically better, and where the right amount depends entirely on your own bloodwork. Giving everyone the same dose regardless of their labs made no sense to us, and iron is also one of the most common reasons a prenatal is hard on your stomach.

Why does your energy come back, and what if it does not?

For most women, energy lifts somewhere between week 13 and week 16. Hormone levels settle, nausea eases, and you can eat properly again, which by itself changes how you feel by three in the afternoon.

For plenty of others it does not lift, and being told this is the easy trimester makes that much harder to bring up. If you are still flattened at week 18, that is worth raising rather than waiting out. Ask about your labs. Tiredness in the middle of pregnancy is usually about iron status, blood sugar or sleep, and all three are things a provider can actually look at.

In the meantime, the boring things do help. Protein at every meal rather than only at dinner. Water before coffee. A snack in the afternoon so you are not running on nothing at four o'clock. None of it is exciting and all of it works better than another espresso.

How does your nutrition change in the second trimester?

The first trimester is about keeping food down. We wrote a whole guide on what to eat when nothing sounds good, because that is a genuinely hard stretch.

The second trimester is different. Appetite returns, aversions fade, and your baby moves into a period of fast growth. The nutrients that carry that growth move to the front of the list.

Choline

Choline plays a role in early brain development, and the adequate intake during pregnancy is 450 mg a day.² Most people fall short of that, and most prenatals do not help, because choline is bulky and expensive and gets cut first when a brand is trying to fit everything into one small pill.

Eggs are the most reliable food source. Salmon, chicken, beef and soybeans all contribute. If you want the longer version, we wrote about why choline is the most overlooked nutrient in prenatal care.

Calcium and magnesium

Your baby's skeleton is hardening through the middle of pregnancy, which is why calcium demand climbs now rather than at the start. Dairy, fortified plant milks, tinned sardines with the bones, tofu and leafy greens all count.

Magnesium tends to come up around the same point, usually in a conversation about leg cramps at two in the morning or sleep that has gone patchy. The form matters here. Chelated minerals such as magnesium bisglycinate are bound to an amino acid, and they are generally gentler on digestion than the oxide and sulfate forms that show up in cheaper formulas.

Folate, and the form on your label

Folate does not stop mattering once the neural tube has closed. It keeps working on cell division and red blood cell production straight through pregnancy, which is exactly what your body is doing more of right now.

What is worth checking is the form. Folic acid is synthetic and has to be converted by your body before it can be used. Methylated folate is already in the active form. Both appear on prenatal labels and they are not interchangeable in how your body handles them. We broke the difference down in methylfolate versus folic acid.

Iron

Iron is the one nutrient in this list where the answer is a blood test rather than a rule of thumb. Ask for your levels. If you need iron, your provider will tell you how much and in what form, and that is a far better plan than a fixed dose arriving in a prenatal whether you need it or not.

Second trimester body changes nobody warns you about

All of these are common and most of them go unmentioned until they happen to you.

Round ligament twinges. Sharp, brief, usually low on one side when you stand up too fast.
Nosebleeds and tender gums. Same cause.
Leg cramps at night. Frequently reported from the middle of pregnancy onwards.
Vivid dreams. Nobody has a satisfying explanation and everybody has them.
Skin that changes character. The glow people talk about is largely increased blood flow. Skin can also turn oilier, drier or more reactive in the same weeks.
Appetite that arrives all at once. Usually welcome, occasionally alarming.

Anything that is severe, sudden, one sided and persistent, or accompanied by bleeding, swelling or visual changes belongs in a phone call to your provider rather than a search bar.

Sleep in the second trimester, and setting it up now

This is the last easy stretch for sleep, which makes it the right moment to build the habits rather than the moment to coast.

Move to side sleeping now while it is still a preference rather than a necessity. A pillow between your knees helps more than it sounds like it should.
Finish your last big drink an hour before bed. You will still be up in the night, just less often.
Eat something with magnesium in it at dinner. Leafy greens, nuts, beans, whole grains.
Keep the room colder than feels reasonable. Pregnancy runs warm.
If you are awake for more than twenty minutes, get up. Lying there awake teaches your body the wrong thing.

Questions to ask at your 20 week appointment

Twenty week appointments go quickly, and it is easy to leave holding a scan photo with none of your own questions answered. These are the five worth writing down beforehand.

Have my iron levels been checked, and when will they be checked again?
Is there anything in my diet you would want me to add or change from here?
What form of folate is in the prenatal I am taking, and is that the one you would choose?
Is my prenatal giving me enough choline, or should I be getting more from food?
What should I watch for between now and 28 weeks?

How we built Mothersense Prenatal+ for this stretch

I built Mothersense because I could not find a prenatal I could keep taking. Real doses of the nutrients that matter in the middle of pregnancy do not fit into one small pill, and every brand I looked at had solved that by cutting something.

So we did the opposite. One daily packet holds seven pills, three tablets and four softgels, which is what it takes to carry clinically meaningful amounts without dropping anything. It provides 950 mg of total choline. Folate is 400 mcg of methylated folate. The minerals are in chelated and malate forms. There is no iron, so you and your provider can dose that to your labs.

You tear open one sachet a day and take it with a meal, which helps prevent stomach upset. If you want to see the full breakdown, every nutrient and the form it comes in is on our ingredients page.

What to do next

Put the anatomy scan and the glucose screening in your calendar today, even if the dates are approximate.
Write the five questions above in your phone so they are there at your next appointment.
If iron has not been checked, ask for it. You can also order your own panel through our Vanguard Performance Labs partnership and bring the results to your provider.
Go and read the label on the prenatal in your cupboard. If you are not sure what you are looking at, our guide to reading a prenatal label walks through the panel line by line.
If your prenatal is not sitting well, change it now rather than at 30 weeks. The middle of pregnancy is the easiest window to switch.
Start sleeping on your side this week.

Second trimester questions we hear most

When does the second trimester start and end?

The second trimester runs from the beginning of week 13 through the end of week 27. That is roughly months four, five and six.

When does energy come back in the second trimester?

For most women energy lifts between week 13 and week 16, as nausea eases and appetite returns. If yours has not lifted by around week 18, ask your provider to check your labs rather than waiting it out.

What tests happen in the second trimester?

The two that anchor the trimester are the anatomy scan, commonly between weeks 18 and 22, and screening for gestational diabetes, usually between 24 and 28 weeks.¹ Your provider may order others depending on your history.

What should I eat in the second trimester?

Eat normally and eat regularly, with protein at every meal. Prioritise choline from eggs and fish, calcium from dairy or fortified alternatives, and magnesium from leafy greens, nuts and beans. This is a building trimester rather than a surviving one.

Do I need more calories in the second trimester?

Slightly, and less than most people assume. This is not the trimester to think about eating for two. Focus on what the food is carrying rather than how much of it there is.

Why do I get leg cramps at night in the second trimester?

Night cramps are commonly reported from the middle of pregnancy onwards. Magnesium comes up often in that conversation, from food and from a prenatal that uses a chelated form. If cramps are severe or one sided, or come with swelling or redness, call your provider.

Can I switch prenatals in the second trimester?

Yes, and it is easier now than later. Appetite is steadier and you are not yet in the third trimester. Compare the form of the folate, the form of the minerals and whether iron is included, then give a new one about two weeks before you judge it.

Is it normal to still feel sick in the second trimester?

For some women nausea carries past week 14, and that is more common than the honeymoon trimester framing suggests. Tell your provider rather than assuming you have to wait it out.

This article is for general education and is not medical advice. Talk to your own provider about your pregnancy, your labs and any supplement you are taking.

References

Centers for Disease Control and Prevention. Gestational Diabetes. cdc.gov/diabetes/about/gestational-diabetes.html
National Institutes of Health, Office of Dietary Supplements. Choline: Fact Sheet for Health Professionals. ods.od.nih.gov/factsheets/Choline-HealthProfessional
National Institutes of Health, Office of Dietary Supplements. Calcium: Fact Sheet for Health Professionals. ods.od.nih.gov/factsheets/Calcium-HealthProfessional
National Institutes of Health, Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals. ods.od.nih.gov/factsheets/Magnesium-HealthProfessional
National Institutes of Health, Office of Dietary Supplements. Folate: Fact Sheet for Health Professionals. ods.od.nih.gov/factsheets/Folate-HealthProfessional
National Institutes of Health, Office of Dietary Supplements. Iron: Fact Sheet for Health Professionals. ods.od.nih.gov/factsheets/Iron-HealthProfessional
Office of Disease Prevention and Health Promotion, US Department of Health and Human Services. Nutrition During Pregnancy to Support a Healthy Mom and Baby. odphp.health.gov

Second Trimester Guide: Weeks 13 to 27, What to Expect and What to Ask