Second Trimester: 14 to 27 Weeks

May 11, 2026

During this stage of pregnancy, many women begin showing as the uterus expands and the fetus continues to grow. Along with these changes, it is common for women to experience increased energy, increased appetite, and emotional shifts, such as mood swings. By the end of the fifth month, most women can feel the first movements and kicks. These early movements, known as “quickening,” often feel like gentle flutters or tiny bubbles.

As development progresses, the fetus becomes more active and responsive. They may react to sounds by moving or by an increased heart rate, and they frequently shift positions in the womb. They can also respond to external stimuli such as sound, light, and pain. By this point, they are capable of sucking their thumb, yawning, stretching, and making facial expressions.

14 Weeks LMP

• Eyelashes have started to grow.

• The external genitalia is developed enough to determine the sex of the fetus by ultrasound.

• Unique fingerprints are forming.

15 Weeks LMP

• The fetus uses amniotic fluid to practice breathing.

• The lungs continue to develop, and bronchioles are starting to form.

• The fetus begins to make more movements, like sucking its thumb or smiling.

16 Weeks LMP

• Ears are now developed enough for the fetus to start hearing your voice, heartbeat, and stomach growling.

• The eyes remain closed, but the fetus can react to light stimuli.

• The fetus releases stress hormones in response to being poked with a needle.

17 Weeks LMP

• The heart pumps up to 50 liters of blood per day.

• The fetus is beginning to put on fat, and their skin is thickening.

• Taste buds are forming on the tongue around this time. Studies show that the fetus can detect different flavors in amniotic fluid, especially between sweet and bitter.

18 Weeks LMP

• The fetus is covered in peach fuzz-like hair called lanugo, which helps keep them warm.

• The fetus can yawn, stretch, and make facial expressions, such as frowning and smiling.

19 Weeks LMP

• The fetus will now concentrate most of its energy on gaining weight.

• By now, they will weigh around 250 grams and can be 9 to 10 inches long, roughly the size of a mango.

20 Weeks LMP

• The fetus can hear sounds outside the mother’s body.

• In response to loud noises, they can cover their ears with their hands and may even become startled or "jump."

• Regular movement, such as twisting, turning, wiggling, punching, and kicking, occurs.

Week 21 LMP

• Rapid Eye Movement (REM) is detectable and can be recorded. This is an indicator of dreaming.

• Fetal sleep patterns and circadian rhythm cycles form. This includes sleeping, waking, and nestling in their most comfortable position.

• After waking up, the fetus will stretch and exercise their muscles energetically.

• Babies born at about 24 weeks of gestation generally have around a 50 % chance of survival with modern neonatal care.

22 Weeks LMP

• The fetus is moving frequently and beginning to respond to sound, rhythm, and music. Talking or singing to them at this stage may help them become familiar with your voice, which can be soothing after birth.

• If the fetus is a girl, her ovaries have already formed and continue to develop.

23 Weeks LMP

• The bone marrow is becoming the primary site of blood cell production.

• The fetus is producing white blood cells (leukocytes).

24 Weeks LMP

• Increasing body fat helps smooth the skin, making it look less wrinkled and plumper.

• The nervous system is also developing rapidly, with growing connections that support movement, sensation, and brain activity.

25 Weeks LMP

• The fetus is beginning to produce melanin, the pigment that gives skin, hair, and eyes their color.

• The lungs are also making increasing amounts of surfactant, an important substance that helps keep the air sacs open and supports breathing after birth.

26 Weeks LMP

• The fetus can open its eyes, blink, and even move them in response to light.

• Nerve connections between the eyes and the brain are forming, allowing the fetus to begin detecting light and dark.

• The eyes can also produce tears.

• Vision won’t be fully functional until several months after birth.

27 Weeks LMP

• The fetus will begin to rotate into a head‑down position in preparation for birth.

• At the end of the seventh month, the fetus is approximately 14 inches long from head to toe and weighs about 2 pounds, continuing to grow and gain body fat each week.

Fetal and embryological development occur rapidly. If you would like a more in-depth understanding of what happens during pregnancy and the developmental milestones, you can speak with your doctor or contact us.

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[2] Mayo Clinic. (2020, February 27). Fetal development: The second trimester.https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/fetal-development/art-20046151

[3] WebMD. (n.d.). Pregnancy timeline: How your baby develops week to week.https://www.webmd.com/baby/interactive-pregnancy-tool-fetal-development

[4] Branum, A. M., & Ahrens, K. A. (2017). Trends in timing of pregnancy awareness among U.S. women. Maternal and Child Health Journal, 21(4), 715–726.https://doi.org/10.1007/s10995-016-2155-1

[5]Cleveland Clinic. (2024, March 19). Fetal development: Week-by-week stages of pregnancy.https://my.clevelandclinic.org/health/articles/7247-fetal-development-stages-of-growth

[6] Behl, G. (2025, April 9). Pregnancy stages week by week: How your baby develops from conception to birth. Medanta.https://www.medanta.org/patient-education-blog/pregnancy-stages-week-by-week-how-your-baby-develops-from-conception-to-birth