Week 13 pregnancy: Fetal development, new symptoms, and bump progress
- Updated Dec 2, 2024
- Published
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Created with Nataliia Yermolovych, MD, Obstetrician-Gynecologist
At 13 weeks pregnant, your baby is growing quickly and developing distinct features. You may start to notice a small bump, and symptoms like fatigue and nausea may begin to ease. This week marks the start of the second trimester.
Congratulations on reaching 13 weeks pregnant! This week, you’re officially entering the second trimester, a stage often called the “honeymoon phase” of pregnancy, as many women start feeling more energized and experience reduced nausea. Let’s dive into what’s happening with your baby, the changes you might notice in your body, and what to expect as you journey through week 13.
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13-week pregnancy symptoms
As you enter the second trimester, some early symptoms may begin to lessen while others emerge. Here’s what you may experience at 13 weeks:
- Reduced nausea: Many women notice that morning sickness begins to subside around this time, bringing welcome relief.
- Energy boost: As hormones stabilize, fatigue may decrease, giving you a boost in energy.
- Appetite Changes: Your appetite might increase, and cravings may become more pronounced as your baby continues to grow.
- Headaches: Hormonal shifts and increased blood volume can lead to occasional headaches, so stay hydrated and rest when needed.
- Visible bump: Some women start noticing a small bump, especially if they’re petite or have had previous pregnancies.
It’s beneficial to track pregnancy symptoms in an app to monitor the easing of fatigue and nausea as you enter the second trimester.
👉Find out more: Entering week 12: Baby development, belly changes, and pregnancy care tips
Your body at 13 weeks pregnant
At 13 weeks, your uterus is expanding further, giving rise to a more noticeable bump in some women. Hormone levels are leveling out, which often leads to a reduction in nausea and fatigue. You may also find your appetite returning or even increasing, as your body works to meet the growing nutritional demands of pregnancy. Continue focusing on a balanced diet and hydration, and remember to listen to your body’s need for rest.
13-week baby bump
A 13-week bump can vary widely based on body type, muscle tone, and whether this is your first pregnancy. Some women may have a subtle bump by now, while others may not show for a few more weeks. Embrace the changes as they come, knowing that each body is unique.
Baby development at 13 weeks pregnancy
At 13 weeks, your baby’s organs and body systems are in place and continue to grow and develop. The baby’s facial features are becoming more distinct, with a tiny nose, lips, and even eyelids starting to take shape. The intestines are moving into the abdomen, and the vocal cords are beginning to form. Your baby is also moving more frequently, though these movements are still too faint to feel.
13-week baby size
The 13-week fetus size is around 3 inches long and weighs approximately 0.8 ounces—about the size of a peach. As your baby continues to grow, limbs are lengthening, and bones are strengthening.
13-week ultrasound
A 13-week ultrasound can reveal incredible details, such as the baby’s head, arms, legs, and even tiny fingers and toes. A 13-week ultrasound 3D scan can provide a more detailed view, where you may observe facial structures and small body movements. At this stage, you may begin to see the baby’s unique features, but it’s still early for a definitive gender reveal.
Actual 13-week fetus
A real-life 13-week fetus resembles a miniature newborn, with recognizable arms, legs, and a defined face. The skin is still translucent, and although movement is frequent, it remains too light for you to feel.
13 weeks pregnant: Second-trimester tests to expect
- Sequential screening
Sequential screening is a two-part test to assess the risk of genetic abnormalities and neural tube defects:
- Part 1 (first trimester): A blood test (PAPP-A and free beta-hCG) and a nuchal translucency ultrasound to estimate risks for Down syndrome (Trisomy 21) and Edwards syndrome (Trisomy 18).
- Part 2 (second trimester): Between 15–22 weeks, a quad screen measures AFP, hCG, estriol, and inhibin-A, providing a more complete risk assessment.
This non-invasive test helps identify pregnancies at higher risk, but it doesn’t provide a definitive diagnosis. Further tests like amniocentesis or CVS may be recommended for high-risk cases.
- Basic blood and urine screening
Regular screenings help identify conditions like anemia, gestational diabetes, and infections early, reducing risks for both mother and baby.
- Blood Screening:
- Hemoglobin and hematocrit levels: Check for anemia.
- Blood type and Rh factor: Assess Rh incompatibility risks.
- Infections: Tests for HIV, syphilis, and hepatitis B to prevent transmission.
- Urine Screening:
- Protein: Elevated levels can indicate UTIs or preeclampsia.
- Glucose: High levels may suggest gestational diabetes.
- Infection indicators: Leukocytes or nitrites indicate UTIs.
- Ketones: May indicate dehydration or inadequate intake.
👉Find out more:
14 weeks pregnant: Baby’s size, bump beginnings, and self-care tips
15 weeks pregnant: Baby’s growth, bump progress, and what to expect
Health tips and self-care at 13 weeks pregnant
- Eat nutrient-dense foods: Choose foods rich in fiber, protein, vitamins, and minerals to support your baby’s growth and sustain your energy.
- Stay hydrated: With increased blood volume, staying hydrated is key to preventing headaches and maintaining circulation.
- Get gentle exercise: Activities like walking, yoga, and swimming can help boost energy, relieve stress, and support circulation.
- Wear comfortable clothing: As your belly grows, maternity or loose-fitting clothes can help you feel more comfortable throughout the day.
Track your symptoms with Femia and get tailored
health advice right on your phone
Questions from the Femia community
When will I experience the first kick?
Most women feel the first fetal movements, known as “quickening,” between 16 and 25 weeks, though it may happen earlier in subsequent pregnancies.
What is the frequency of ultrasounds?
Typically, ultrasounds are performed around 8-12 weeks, 18-20 weeks, and later if needed. The frequency may vary based on your healthcare provider and specific health needs.
How can I manage headaches at 13 weeks?
Staying hydrated, getting enough rest, and managing stress can help reduce headaches. Avoid caffeine and consult your provider if headaches persist.
How can I track my weight gain?
Tracking your weight gain during pregnancy involves regular check-ins to ensure you're within the recommended range based on your pre-pregnancy BMI and individual needs. Using a pregnancy weight gain calculator can help you monitor healthy weight gain and adjust your diet or activity level as needed. Additionally, your healthcare provider will track your progress during routine prenatal visits and provide guidance to support your health and your baby’s development.
The bottom line
At 13 weeks pregnant, your baby is growing rapidly, with organs forming and bones strengthening. You may notice a slight bump as your uterus expands, and symptoms like nausea and fatigue may begin to ease. Focus on balanced nutrition, hydration, and light activity to support your body and baby as you progress through the second trimester.
References
- “13 Weeks Pregnant: Symptoms, Baby Development & Tips.” BabyCenter, www.babycenter.com/pregnancy/week-by-week/13-weeks-pregnant.
- “Week 13 of Pregnancy: Symptoms, Baby Development & More.” What to Expect, www.whattoexpect.com/pregnancy/week-by-week/week-13.aspx.
- “13 Weeks Pregnant: Baby Development, Symptoms & Tips.” NHS, www.nhs.uk/pregnancy/week-by-week/1-to-12/13-weeks/.
- “Pregnancy Week 13: What to Expect.” American Pregnancy Association, www.americanpregnancy.org/healthy-pregnancy/week-by-week/13-weeks-pregnant/.
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