The Second Trimester of Pregnancy: What to Expect and Why It Matters

The second trimester is often referred to as the “honeymoon phase” of pregnancy—and for good reason. For many women, the nausea of the first trimester subsides, energy levels return, and that beautiful baby bump starts to show. But beyond the glow, this trimester is also medically significant, with key developmental milestones and screenings taking place.

When Is the Second Trimester?

The second trimester spans from week 13 to week 27 of pregnancy. It’s a time of rapid fetal growth and increasingly visible physical changes in the mother.

What’s Happening in Your Body?

Your Baby’s Development – from week 13 onwards, your baby is no longer called an embryo but a fetus—and the transformation is remarkable:

✔️Size & Growth: From about 7 cm to 36 cm by the end of week 27.

✔️Organ Function: The liver begins to produce bile, the pancreas starts insulin production, and kidneys create urine, which is excreted into the amniotic fluid.

✔️Movement & Senses: The nervous system matures, reflexes develop, and the baby starts to move, stretch, and react to sound and light. You may feel these movements—called quickening—around week 20.

✔️Lung Training: Breathing is practiced through the rhythmic intake and outflow of amniotic fluid, often causing hiccups.

✔️Protection: The baby’s skin becomes covered with a waxy substance (vernix) and soft hair (lanugo), which help protect it in the womb.

By the end of the second trimester, your baby is potentially viable outside the womb with intensive care—though nature’s best place remains your belly for now.

Changes in Your Body:

✔️Most women experience a relief from morning sickness.

✔️Energy levels improve, and appetite returns.

✔️The uterus expands, and the baby bump becomes more prominent.

✔️Common symptoms may include: round ligament pain, mild backache, skin changes, and increased vaginal discharge (which is usually normal).

Key Medical Appointments in the Second Trimester

1. Organ Screening Ultrasound (Second Trimester Scan):

✔️Usually done between week 20 and 22.

✔️This is a comprehensive anatomical scan of the fetus.

✔️It evaluates:

  • The brain, spine, heart, stomach, kidneys, bladder
  • The face, including the lips (to screen for cleft lip)
  • The limbs and placental location

✔️Many congenital anomalies can be detected at this stage.

✔️It is non-invasive, but extremely important for both reassurance and early intervention planning if needed.

Note: In Austria, this is known as the Organscreening and is often done at a specialized center, and most of the time is private to pay.

2. Important Screenings Between Weeks 25–28 – Routine Blood Work & Glucose Testing

✔️Screening for anemia, iron deficiency, and blood sugar irregularities.

✔️HBs-Antigen Test (Hepatitis B screening):
This blood test checks whether the mother is a carrier of the hepatitis B virus.

  • If positive, steps can be taken to protect the baby at birth through vaccination and immunoglobulin.
  • Preventing perinatal transmission is crucial, as chronic hepatitis B can cause long-term liver disease in infants.

✔️Oral Glucose Tolerance Test (OGTT):
This is a standard screening for gestational diabetes. It involves drinking a glucose solution and measuring blood sugar levels at intervals.

  • Recommended between week 25 and 28, as insulin resistance naturally increases during this phase of pregnancy.
  • Early detection of gestational diabetes helps prevent complications such as:
    • Excessive fetal growth (macrosomia)
    • Premature birth
    • Cesarean delivery
    • Risk of future type 2 diabetes in mother and child

These tests are crucial for prevention and early intervention, ensuring a safer delivery and healthier outcomes for both mother and baby.

3. Cervical Length Assessment

  • In women at risk of preterm labor, a vaginal ultrasound may be performed to assess the length of the cervix.

Contraindications and Cautions in the Second Trimester

While the second trimester is often referred to as the most comfortable phase of pregnancy, there are still a few important precautions to keep in mind:

Avoid:

  • Contact sports or high-impact activities such as kickboxing, horseback riding, or skiing – these carry a high risk of falls or abdominal injury.
  • Lying flat on your back (especially after week 20) for extended periods. The growing uterus can compress major blood vessels like the inferior vena cava, leading to reduced blood flow and dizziness.
  • Heavy lifting or intense core exercises that strain the abdominal wall.

Be Cautious With:

  • Saunas, hot baths, and thermal spas – overheating can be risky during pregnancy:
    • Water temperature should not exceed 37–38°C (98.6–100.4°F).
    • Prolonged exposure to high temperatures can increase the risk of neural tube defects and may cause dizziness or dehydration.
    • This applies even to natural hot springs—like those found in Iceland—where water can sometimes be much hotter. Always check the temperature beforehand.

Pro tip: If the water feels hotter than a warm bath or causes you to sweat excessively or feel lightheaded, it’s too hot. Keep thermal soaks short and always stay well hydrated.

Medications:

  • Always consult your OB-GYN before taking any medications—even over-the-counter ones.
  • Certain drugs (e.g. NSAIDs like ibuprofen) are contraindicated, especially after the 20th week.

When to Seek Medical Attention:

  • Vaginal bleeding
  • Severe abdominal pain
  • High fever
  • Sudden swelling of hands or face
  • Decreased fetal movements (especially later in this trimester)

Mental & Emotional Health

This is also a great time to start connecting with your baby emotionally—many parents start talking or playing music to the baby. However, don’t hesitate to reach out for support if you’re experiencing anxiety, fear, or emotional ups and downs. Hormones and life changes can be overwhelming.

Final Thoughts

The second trimester is an exciting, often more comfortable chapter of pregnancy. It’s a time to celebrate milestones, but also to stay informed and attentive. Be sure to attend all your prenatal appointments, ask questions, and listen to your body. A good balance of rest, healthy nutrition, gentle movement, and emotional support can help set the foundation for a healthy pregnancy and birth.

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