Week 13: The Second Trimester Begins

Welcome to the second trimester! Many people call this the golden period of pregnancy, and it is easy to understand why. Nausea is easing, energy is returning, and the risk of complications is significantly lower. Your baby is now about 7 cm long and weighs around 25 grams — the size of a peapod.

For many, this is the week where pregnancy really starts to feel positive. You have passed the most vulnerable stage, and the little one growing inside you is developing at a remarkable pace. According to ACOG and the NHS, the risk of miscarriage drops significantly once a heartbeat has been confirmed around week 12 — down to around 1–2%.

This week also marks an important biological transition: the placenta has now completely taken over hormone production from the ovaries. This is one of the main reasons nausea eases and you begin to feel more like yourself again.

Baby's Development

Fingerprints forming: The unique patterns on your baby's fingertips begin to take shape this week. No one else in the world will ever have the same ones
Vocal cords developing: Your baby's vocal cords are forming now, though it will be many months before they are used to make sounds
Baby is swallowing amniotic fluid: The fetus is practising swallowing and digesting — important preparation for life outside the womb
Body growing fast: The body is beginning to grow faster than the head, so proportions are gradually becoming more balanced
Face taking shape: The eyes have moved closer together, and the ears are nearly in the right position. Your baby is starting to look like a little person
Intestines in place: The intestines, which temporarily protruded into the umbilical cord, are now pulling back into the abdominal cavity
Kidneys at work: The kidneys are beginning to produce urine, which is released into the amniotic fluid — an important part of the amniotic fluid cycle
Size: The fetus is about 7 cm long (crown to rump) and weighs around 25 grams

The Placenta Takes Over

At week 13, the placenta has completely taken over the production of progesterone and oestrogen from the ovaries. This is one of the reasons nausea eases — hCG levels drop and hormone production stabilises. The placenta also filters nutrients and oxygen from your blood to your baby's blood, and removes waste products in the other direction.

The placenta is a fascinating organ, unique to pregnancy. It weighs around 50 grams now but will grow to about 500–600 grams by full term. Throughout pregnancy it filters around 500 litres of blood per day, ensuring your baby receives everything it needs. It also acts as a barrier, preventing many harmful substances from reaching your baby.

Your Body

Energy returning: Many people notice a significant energy boost. The constant fatigue from the first trimester eases for most
Pregnancy glow: Increased blood circulation can give the skin a rosy glow. Some also notice clearer skin
Bump beginning to show: The uterus is rising above the pelvis, and you may see a small baby bump for the first time
Better mood: Hormone levels are stabilising, and the worst mood swings from the first trimester are calming down
Lower risk: The risk of miscarriage has dropped significantly — down to around 1–2% after a confirmed heartbeat at week 12
Better appetite: Nausea is easing, and many find their appetite returns in full force
Libido may increase: Some experience increased sexual desire in the second trimester due to increased blood flow to the pelvic area
Increased blood volume: Your body is already producing more blood than usual, and you may feel warmer and sweat more easily

Linea Nigra

Some pregnant people begin to see a dark line from the navel down across the abdomen. This is called linea nigra and is caused by increased melanin production due to hormones. It is completely harmless and typically fades within a few months after birth.

Linea nigra is most common in people with darker skin, but can occur in anyone. It typically runs from the navel down to the pubic bone, and for some also extends above the navel. There is no way to prevent it, and it requires no treatment.

Good to Know

Now that energy is returning, it is a great time to establish regular exercise habits. WHO and ACOG recommend at least 150 minutes of moderate activity per week during pregnancy. Walking, swimming, and prenatal yoga are particularly good options that are safe throughout pregnancy.

It may be worth investing in a few maternity clothing items now. Trousers with elastic waistbands and soft, stretchy tops offer good comfort as your bump grows. You do not need to buy much — a few key pieces are enough.

Many people choose to share their pregnancy news with friends, colleagues, and extended family now that the first trimester is over. Do it at your own pace — there are no rules about when you "must" tell. Know that in most countries, employees have legal protections during pregnancy and the right to reasonable accommodations.

Now is also a good time to plan ahead. Use our due date calculator to track important dates.

The Second Trimester — The Golden Period

The second trimester runs from week 13 to week 27 and is considered the most comfortable part of pregnancy for most people. Here is what you can look forward to in the coming weeks:

Weeks 13–16: Adjustment and New Energy

Nausea eases, energy returns, and your body adjusts to the new hormonal balance. Many experience a noticeable improvement in mood and quality of life. The bump is beginning to show, and it may be a good time to share the news.

Weeks 17–20: Anatomy Scan and First Kicks

Between weeks 17 and 20, the anatomy ultrasound is offered — a thorough examination of your baby's organs. Many feel the first fetal movements during this period — one of pregnancy's most magical moments. At week 20 you are halfway!

Weeks 21–27: Growth and Preparations

Your baby grows rapidly, and the bump becomes obvious to everyone. It is time for childbirth preparation classes, planning the nursery, and practical preparations.

Prenatal Care Around Week 13

Nuchal Translucency / First Trimester Screening

Between weeks 11 and 14, you may have had or will soon have a first trimester screening:

What it is: An ultrasound measuring fluid at the back of your baby's neck, combined with blood tests
What it shows: Gives a risk assessment for trisomy 21, 18, and 13
Voluntary: You choose whether to have the test. It is an offer, not a requirement
Result: The vast majority receive reassuring results
NIPT: If screening shows elevated risk, NIPT (Non-Invasive Prenatal Test) may be offered for a more accurate result

Upcoming Checks

Routine appointment with midwife: About every 4 weeks in the second trimester
Anatomy scan: Between weeks 17 and 20 — a thorough examination of your baby's organs
Blood tests: Haemoglobin and iron levels checked regularly

Nutrition

Now that appetite has returned, it is a good time to focus on a nutritious diet:

Key Nutrients in the Second Trimester

Iron: Needs increase significantly. Good sources: lean meat, beans, lentils, dark leafy greens
Calcium (around 1,000 mg/day): For your baby's bone development. Dairy products, broccoli, kale, almonds
Protein: Important for your baby's growth. Eat protein-rich food at every meal
Omega-3 (DHA): For brain development. According to WHO and ACOG, eat oily fish 2–3 times a week
Vitamin D (600 IU/day): Important year-round. Supplements recommended for most pregnant people
Folic acid: Can be stopped after week 12, but many continue throughout pregnancy

Weight Gain in Pregnancy

Recommended total weight gain depends on your pre-pregnancy BMI:

BMI under 18.5: 12.5–18 kg
BMI 18.5–24.9: 11.5–16 kg
BMI 25–29.9: 7–11.5 kg
BMI over 30: 5–9 kg

Weight gain should happen gradually. In the second trimester, about 0.5 kg per week is normal. Do not weigh yourself too often — weekly is more than enough. Remember that weight gain is not just the baby — it includes the placenta, amniotic fluid, increased blood volume, larger breasts, and uterus.

Foods to Avoid During Pregnancy

According to WHO, ACOG, and the CDC, pregnant people should avoid:

Raw or undercooked meat and fish (risk of toxoplasmosis and listeria)
Soft cheeses and mould-ripened cheeses (risk of listeria)
Unpasteurised dairy products
High quantities of liver (due to vitamin A)
High-mercury fish (shark, swordfish, king mackerel, tilefish)
Alcohol (no safe amount)
More than 200 mg caffeine daily (about 2 cups of coffee)

Exercise and Physical Activity

Now that energy is back, this is the perfect time to establish good exercise habits:

Walking: 30 minutes daily for good cardiovascular fitness and fresh air
Swimming: Relieves joint stress and provides full-body exercise. Many pools offer dedicated prenatal classes
Prenatal yoga: Strengthens, stretches, and provides mental calm. Breathing exercises are valuable preparation for birth
Kegel exercises: Start now to prepare your body for birth and recovery
Adapted strength training: Focus on back, legs, and pelvic floor

According to ACOG, pregnant people should be physically active for at least 150 minutes per week at moderate intensity. Activity can be broken into shorter sessions throughout the day. Avoid contact sports and activities with a high risk of falling.

Benefits of Regular Exercise

Research shows that regular physical activity during pregnancy provides many benefits:

Reduced risk of gestational diabetes
Better sleep quality and more energy in daily life
Less back and pelvic pain
Better mental health and mood
Easier birth and faster recovery
Prevention of excessive weight gain
Lower risk of pre-eclampsia

Moderate intensity means you can hold a conversation while exercising, but become somewhat breathless. Listen to your body and reduce intensity if uncomfortable.

Mental Health During Pregnancy

The transition to the second trimester is often a relief, but it does not mean all worries disappear. It is entirely normal to have mixed feelings during pregnancy:

Common Emotional Reactions

Joy and anticipation mixed with anxiety and uncertainty
Worry about your baby's health, especially before test results
Relief at having passed the most vulnerable period
Mood swings due to hormonal changes
Thoughts about how life will change

What Can Help

Talk openly with your partner about your feelings
Maintain contact with friends and family
Regular physical activity is proven to improve mental health
Seek professional help if you experience persistent sadness or anxiety

According to the NHS and ACOG, pregnant people experiencing symptoms of depression or anxiety should contact their midwife or GP. There is good treatment available that is safe during pregnancy.

For Partners

Plan something enjoyable to celebrate the start of the second trimester. A dinner out, a trip, or a quiet evening together
Start talking about practical things you can do together, such as clearing space for the baby at home
Help find exercise activities you can do together, such as nature walks or swimming
Help share the news with friends and family when your partner is ready
Start thinking about parental leave and how you would like to divide it

Tips for Week 13

Get started with exercise: Walking, swimming, or prenatal yoga are good and safe options. Kegel exercises are also valuable — it is never too early to start
Update your wardrobe: A few comfortable maternity items make daily life much easier going forward
Enjoy the increased energy: The second trimester is often the most comfortable period. Make the most of it!
Share the news: If you have not told people yet, this is a natural time to share
Book your anatomy scan: Check with your midwife that your anatomy scan appointment (weeks 17–20) is booked
Document your bump: Start with weekly bump photos — you will appreciate them later
Check your rights: Read about parental leave and pregnancy rights with your employer
Follow the timeline: Keep track of what is happening week by week throughout pregnancy

When to Contact Your Doctor

Contact your doctor or midwife if you experience:

Persistent pain in the lower abdomen
Bleeding, even if only a little
Severe headache that does not respond to paracetamol
Burning or pain when urinating (may indicate a urinary tract infection, which is more common in pregnancy)
Severe itching all over the body (may indicate intrahepatic cholestasis of pregnancy)
Fever above 38°C (100.4°F)
Watery discharge that may indicate amniotic fluid leaking

Constipation in Pregnancy

Many pregnant people experience constipation in the second trimester. According to the NHS and ACOG, this is mainly caused by the hormone progesterone, which slows down the bowel, as well as iron supplements that many begin taking now.

What Can Help

Eat fibre-rich food daily: whole grain products, vegetables, fruit, dried fruits (prunes are particularly effective)
Drink at least 1.5–2 litres of fluid daily
Be physically active — daily walks stimulate the bowel
Eat regularly and at regular times
Prunes and prune juice are a natural and safe aid
Talk to your midwife about gentle laxatives if lifestyle changes do not help

Preventive Tips

Start the day with a glass of warm water
Choose wholegrain bread over white bread
Eat fruit as a snack between meals
If you take iron supplements, try switching to a more tolerable formulation (discuss with your midwife)

Your Workplace Rights During Pregnancy

As you may be considering telling your employer about your pregnancy, it is useful to know your rights. In most countries, pregnant employees are entitled to:

Protection against dismissal due to pregnancy
Paid time off for prenatal appointments
Reasonable workplace adjustments when needed
Maternity/parental leave

Check the specific laws in your country — most have strong protections in place. If your job involves heavy lifting, physical demands, chemical exposure, night work, or extended standing, tell your employer earlier so appropriate accommodations can be arranged.

Did You Know?

Fingerprints are completely unique: From week 13, the unique patterns on your baby's fingertips begin to form. Not even identical twins have identical fingerprints — the patterns are influenced by tiny variations in the amniotic fluid and pressure against the skin
Your baby is practising breathing: Even though there is no air in the lungs, the fetus makes breathing movements with its chest. This is important training for the first breath after birth
You have much more blood now: Your body has already started producing significantly more blood to supply the placenta. By the end of pregnancy, you will have almost 50% more blood than normal — about 1.5 extra litres
Your baby can swallow: The fetus is actively swallowing amniotic fluid this week. It is important training for the digestive system and also helps regulate the amount of amniotic fluid
Intestines are finally in place: The intestines, which temporarily protruded into the umbilical cord, have now pulled back into the abdominal cavity — an important developmental milestone that marks the transition to the second trimester

Travel During Pregnancy

The second trimester is the most popular time for a babymoon — a holiday before the baby arrives. Weeks 13–27 are generally considered the safest period for travel.

Flying

Most airlines allow pregnant passengers to fly until week 36 (week 32 for twins)
Drink plenty of water to stay hydrated
Move regularly during the flight to prevent blood clots
Wear compression stockings on long flights
Carry your maternity notes in case medical help is needed

Car Travel

Wear your seatbelt with the shoulder strap over your shoulder and the lap belt below your bump
Take regular breaks to stretch your legs (at least every 2 hours)
Bring food and drink to keep your blood sugar stable

Insurance

Check that your travel insurance covers pregnancy-related events
Inform your midwife about your travel plans

Frequently Asked Questions About Week 13

What does it mean that the second trimester is the "golden period"?

The second trimester (weeks 13–27) is often called the golden period because nausea typically eases, energy returns, and the bump is not yet so large that it is uncomfortable. Many find this the most comfortable part of pregnancy. It is a great time for travel, exercise, and social activities. Your body has adapted to the hormone levels, and you feel more like yourself again.

When should I tell my employer?

There is no fixed rule about when you must inform your employer, but it is practical to do so early enough to plan your leave. Many people tell them after weeks 12–13. Know your rights — most countries have laws entitling you to time off for prenatal appointments and protecting you from dismissal due to pregnancy.

Is it normal for the bump to look uneven?

Yes, it is completely normal. The bump may look slightly asymmetrical because the uterus grows unevenly and your baby's position varies. Some days the bump may look larger than others, depending on bloating and how your baby is lying. The shape of the bump tells you nothing about your baby's sex — that is a myth.

Do I need special maternity clothes already?

Not necessarily, but many notice that regular trousers start to feel tight around weeks 13–14. A hair tie through the button hole of your jeans is a classic trick. Eventually it is worth investing in comfortable trousers with elastic waistbands.

Is sex safe in the second trimester?

Yes, sex is safe throughout pregnancy for most people. Your baby is well protected by amniotic fluid and the cervix. Many actually experience increased sexual desire in the second trimester due to increased blood flow to the pelvic area. Talk to your midwife or doctor if you have specific concerns, such as a low-lying placenta or preterm labour risk.

Can I start planning the nursery now?

Absolutely! Many start planning the nursery in the second trimester, when energy is back and risk is lower. Start with the essentials: cot, mattress, and storage.

What are first trimester screening and NIPT, and should I have them?

First trimester screening is done between weeks 11 and 14 and gives a risk assessment for chromosomal differences like trisomy 21 (Down syndrome), 18, and 13. It is a screening test, not a diagnostic test — it gives a probability, not a definitive answer. It is voluntary. If it shows elevated risk, NIPT (Non-Invasive Prenatal Test) may be offered, which is a more accurate blood test. Talk to your midwife about what is right for you.

When should I start Kegel exercises?

The sooner, the better! Week 13 is an excellent time to start. Strong pelvic floor muscles prepare your body for birth, prevent urinary leakage during and after pregnancy, and help with recovery afterwards. Start with 3 sets of 8–10 repetitions daily. Hold each contraction for 5–10 seconds, and relax equally long between each one.

How much should I drink during pregnancy?

According to WHO and ACOG, pregnant people should drink at least 1.5–2 litres of fluid daily, and more during physical activity, hot weather, or constipation. Water is best, but milk, juice, and soups also count. Adequate fluid helps with constipation, dry skin, headache, and urinary tract infections. Keep a water bottle with you throughout the day.

What does it mean that the placenta has "taken over"?

At week 13, the placenta has completely taken over the production of progesterone and oestrogen from the ovaries. Earlier in pregnancy, the hCG hormone from the ovaries maintained the pregnancy. Now the placenta is an independent organ that filters nutrition and oxygen to your baby, produces hormones, and removes waste products. This transition is one of the main reasons nausea eases — hCG levels drop significantly, and your body adjusts to the more stable hormone production from the placenta.

Should I stop folic acid now?

According to ACOG and the NHS, the recommendation is to take folic acid (400 micrograms daily) through the entire first trimester. After week 12, it is safe to stop since the neural tube is closed. However, many choose to continue with folic acid throughout pregnancy, as it is also important for blood cell production. Talk to your midwife about what is right for you. Many prenatal vitamins contain folic acid, iron, vitamin D, and iodine in one tablet.

Next week: Your baby can make facial expressions, and lanugo (fine body hair) is covering the whole body!