Pregnancy Week by Week
13 Weeks Pregnant
At 13 weeks pregnant, your baby is the size of a lemon. Welcome to the second trimester — learn about fetal development, easing symptoms, and what to expect now.
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This article is for general information and is not a substitute for professional medical advice. Always consult your pediatrician or doctor about your child.
Sources: WHO, CDC, AAP and NHS guidance. Recommendations differ between countries — for local advice see the NHS or ACOG.
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At a Glance: Week 13
- Trimester: Second trimester begins
- Baby's size: About the size of a lemon — roughly 7.4 cm (2.9 in) crown-to-rump and 23 g (0.8 oz)
- Key milestone: Vocal cords are forming, fingerprints are appearing on the fingertips, and the placenta is now fully functional and producing the hormones that will support your baby through the rest of pregnancy.
Week 13 marks a meaningful turning point. The risk of miscarriage drops sharply after the first trimester, energy often returns, and the constant queasiness of early pregnancy starts to lift for many people. You may finally feel ready to share your news, plan ahead, and reconnect with appetite, exercise, and sleep.
Your Baby's Development This Week
At 13 weeks, your baby has transitioned from embryo to fetus and looks distinctly human, although still tiny. Major organs are formed and are now in a long phase of growth, maturation, and refinement.
- Head and brain: The head still makes up about half of the baby's length, but the body is starting to catch up. Brain tissue is forming rapidly, and neurons are connecting at a remarkable pace.
- Face: Eyes have moved from the sides of the head toward the front, and ears are settling closer to their final position. Eyelids are fused shut and will stay closed until around week 26.
- Hands and fingerprints: Tiny unique fingerprints are forming on the pads of the fingers and toes — a one-of-a-kind pattern that will stay with your child for life.
- Vocal cords: Vocal cords begin to form this week, though it will be many months before your baby can make sound.
- Intestines: The intestines, which spent part of the first trimester inside the umbilical cord, are migrating back into the abdomen as space allows.
- Placenta: The placenta has fully taken over hormone production from the corpus luteum and is now responsible for delivering oxygen and nutrients and removing waste.
- Movement: Your baby is kicking, stretching, and even hiccupping, although these movements are too small for you to feel yet.
Your Body and Symptoms This Week
As estrogen and progesterone settle into a more stable rhythm and hCG levels drop from their first-trimester peak, many of the toughest early symptoms ease. Common experiences in week 13 include:
- Fading nausea: Morning sickness eases significantly for most people by 12–14 weeks. Some continue to feel queasy, especially when hungry or tired.
- Increased energy: The crushing fatigue of the first trimester often lifts. Many describe this as the "honeymoon" stretch of pregnancy.
- Visible veins: Blue veins may be more prominent on the breasts, abdomen, and legs as blood volume rises (it will increase by about 45% over the pregnancy).
- Round ligament discomfort: Sharp, brief pains in the lower belly or groin when you change position are caused by ligaments stretching to support the growing uterus.
- Increased discharge: A thin, milky, mildly-scented discharge (leukorrhea) is normal and helps protect against infection.
- Heightened libido: Improved energy and increased blood flow to the pelvis raise libido for many people in the second trimester.
- Bloating, gas, and constipation: Progesterone slows digestion, which is helpful for nutrient absorption but uncomfortable.
- Skin changes: Some people notice the linea nigra (the dark line down the abdomen) or chloasma (darker patches on the face) beginning to appear.
Nutrition: What to Eat and Avoid This Week
In the second trimester, ACOG recommends an additional 340 calories per day. Quality matters far more than quantity — focus on nutrient density to support your baby's growth and your own changing body.
Nutrients to prioritise:
- Folate (600 mcg/day): Continue your prenatal. Add leafy greens, lentils, chickpeas, and fortified grains.
- Iron (27 mg/day): Needs rise sharply now to support expanding blood volume. Lean red meat, poultry, beans, tofu, spinach, and fortified cereals are good sources. Pair plant-based iron with vitamin C for absorption.
- Calcium (1,000 mg/day): Dairy, fortified plant milks, tofu set with calcium, and leafy greens support your baby's developing bones.
- Protein (about 71 g/day): Eggs, fish, chicken, legumes, dairy, nuts.
- Omega-3 DHA: Low-mercury fish such as salmon and sardines support brain development.
- Fiber and fluids: Help relieve constipation. Aim for 8–12 cups of water daily.
Foods to avoid: raw or undercooked meat, fish, or eggs; unpasteurized dairy or juice; deli meats and pâté unless reheated until steaming; high-mercury fish (shark, swordfish, king mackerel, tilefish); raw sprouts; alcohol; and more than 200 mg of caffeine per day (roughly one 12 oz coffee).
Movement and Exercise
With energy returning and the worst nausea fading, week 13 is a great time to rebuild a movement routine. ACOG recommends most pregnant people aim for 150 minutes of moderate-intensity aerobic activity per week, spread across most days.
Safe and recommended: walking, swimming, stationary cycling, prenatal yoga, prenatal Pilates, low-impact aerobics, and light strength training with proper form.
Avoid: contact sports, scuba diving, hot yoga or hot Pilates, exercise at altitude above ~6,000 ft (if unaccustomed), activities with fall risk (skiing, horse riding, gymnastics), and lying flat on your back for prolonged periods. Stop and call your provider if you experience chest pain, dizziness, headache, calf swelling, fluid leakage, vaginal bleeding, or regular painful contractions.
Mental and Emotional Wellbeing
Many people feel a wave of emotional relief crossing into the second trimester — but not everyone. Hormonal shifts, the weight of new responsibility, body changes, and the decision about whom to tell can all stir up complex feelings. Some experience a fresh wave of anxiety around screening test results expected in this window.
Helpful practices: prioritise 7–9 hours of sleep, keep talking with your partner or a trusted friend, journal, get outside daily, and consider prenatal-specific meditation or yoga. The NHS, ACOG, and WHO all stress that perinatal mental health is part of pregnancy care — bring up worries with your provider just as you would physical symptoms. Persistent low mood, panic, intrusive thoughts, or hopelessness deserve professional support.
Common Concerns and When to Call Your Doctor
Call your provider promptly if you experience any of the following at 13 weeks:
- Heavy bleeding, or bright red bleeding that soaks a pad
- Severe or persistent abdominal cramping
- Sharp shoulder pain (can indicate internal bleeding)
- Fever above 38°C (100.4°F)
- Painful urination or strong-smelling urine (possible UTI)
- Sudden severe headache, blurred vision, or upper-right abdominal pain
- Persistent vomiting that prevents you from keeping fluids down
- Severe itching, especially on hands and feet
Light spotting after intercourse or a Pap smear is usually not concerning, but always mention it to your provider so they can advise based on your history.
Tests and Appointments This Week
Week 13 sits at the tail end of the first-trimester screening window. Depending on your care plan, you may have recently had or be scheduled for:
- Nuchal translucency (NT) scan: Performed between 11 and 13 weeks 6 days. It measures fluid at the back of the baby's neck and, combined with a blood test, screens for chromosomal conditions.
- Combined first-trimester screening: A blood test (PAPP-A and free beta-hCG) plus the NT scan.
- Non-invasive prenatal testing (NIPT): Available from 10 weeks onward; can also determine fetal sex.
- Chorionic villus sampling (CVS): An optional diagnostic test usually offered between weeks 10 and 13 for those who want definitive chromosomal results.
Your next routine prenatal visit is usually scheduled around week 16. The major anatomy scan typically takes place between 18 and 22 weeks.
Tips for Week 13
- Start a pregnancy journal. Note symptoms, questions for your provider, and how you're feeling — it becomes a meaningful keepsake and a useful clinical record.
- Invest in a few comfortable transition pieces. Stretchy waistbands, soft bras, and supportive shoes ease the early bump phase before full maternity wear is necessary.
- Rebuild your sleep routine. If you've been napping heavily through the first trimester, start protecting a consistent bedtime to support second-trimester sleep quality.
- Plan how and when to share your news. Many people share after the first-trimester screening. Decide what feels right for your workplace and family.
- Schedule a dental check-up. Pregnancy increases the risk of gum inflammation; routine dental care is safe and recommended.
Preparing for What's Next
The second trimester is the practical "planning window" of pregnancy. Over the next few weeks, you can start to:
- Research childbirth education classes (many fill up early and start around weeks 24–30)
- Choose a paediatrician or family-medicine clinician for your baby
- Review parental leave policies and discuss timing with your employer
- Begin thinking about your birth preferences and the kind of support you want
- Plan for the 18–22 week anatomy scan, when many people choose to learn the baby's sex
There's no rush — most of these decisions can wait several more weeks. Use the renewed energy of week 13 to do what feels useful, and rest when it doesn't.
Frequently Asked Questions About 13 Weeks Pregnant
Is 13 weeks the start of the second trimester?
Yes — most clinicians (including ACOG) consider week 13 the beginning of the second trimester, though a few sources start it at week 14. Either way, you are at the threshold of what many parents describe as the most comfortable stretch of pregnancy. Nausea typically begins to ease, energy returns, and miscarriage risk drops significantly after the first trimester.
Is it normal to still feel nauseous at 13 weeks pregnant?
Yes. While many people see morning sickness improve between weeks 12 and 14, it is completely normal for nausea to linger into the second trimester or even persist throughout pregnancy. If you are vomiting more than three times daily, losing weight, or unable to keep fluids down, contact your provider — these can be signs of hyperemesis gravidarum, which is treatable.
Why am I suddenly so hungry at 13 weeks?
As first-trimester nausea fades, appetite often surges. Your baby is also entering a rapid growth phase and your blood volume continues to expand, both of which increase calorie needs. ACOG recommends only about 340 extra calories per day in the second trimester — roughly a glass of milk and half a sandwich — so focus on nutrient-dense foods rather than doubling portion sizes.
When should I worry about cramping at 13 weeks pregnant?
Mild, occasional cramping from round ligament stretching is normal in early second trimester. Call your provider promptly if cramps are severe, rhythmic, accompanied by bleeding, fever, dizziness, or shoulder pain. Any heavy bleeding or persistent severe pain warrants same-day medical evaluation.
Can I find out the baby's sex at 13 weeks?
Non-invasive prenatal testing (NIPT), a blood test typically offered from 10 weeks onward, can identify fetal sex with very high accuracy by 13 weeks. Ultrasound can sometimes suggest sex this early, but anatomy-scan accuracy (usually 18–22 weeks) is much higher. Discuss timing and options with your provider.
Is it safe to start prenatal exercise at 13 weeks if I haven't been active?
Yes, with provider clearance. ACOG encourages most pregnant people to aim for 150 minutes of moderate aerobic activity weekly. If you are new to exercise, start gently — 10–15 minute walks, prenatal yoga, or swimming — and build gradually. Avoid contact sports, activities with fall risk, hot yoga, and exercises performed flat on your back after the first trimester.
Will I have a noticeable bump at 13 weeks pregnant?
Some parents — especially those in second or later pregnancies — show a clear bump by week 13. First-time parents often still look only slightly fuller through the waist. Bump timing varies widely and depends on body shape, muscle tone, and uterine position. There is no "normal" size at this stage.
Do I still need folic acid at 13 weeks?
Folic acid's most critical role — preventing neural tube defects — happens in the first 12 weeks, but continuing 400–800 mcg daily throughout pregnancy supports red blood cell production and overall fetal development. Most prenatal vitamins include it automatically, so simply keep taking your prenatal as prescribed.
Is it normal to feel emotional or anxious at 13 weeks pregnant?
Yes. Hormonal shifts, plus the mental load of the first-trimester transition, can leave you tearful, irritable, or anxious. Mood usually stabilizes through the second trimester. If sadness, hopelessness, or anxiety persist for more than two weeks or interfere with daily life, talk to your provider — prenatal depression and anxiety are common and treatable.
When will I feel the baby move?
Most first-time parents feel "quickening" — the earliest fetal movements — between 18 and 22 weeks. People who have been pregnant before may notice it as early as 14–16 weeks. At 13 weeks the baby is moving constantly, but is still too small for those movements to be felt through the abdominal wall.
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