Fetal Perspective

Month 4

The fourth month of pregnancy marks the start of the second trimester. This is often referred to as the "golden period" for many mothers because early symptoms like nausea and fatigue usually subside, and the baby begins to grow rapidly. The fetus also starts making more significant movements, though the mother may not feel them yet.

Weeks 13 to 16: Key Developments

Week 13:

Development:

The baby's bones continue to harden, particularly in the arms and legs.

The ribs and vertebrae are forming cartilage that will later turn into bone.

Lanugo, a soft, fine hair, begins to cover the fetus's skin, helping regulate body temperature.

Vocal cords are fully formed, though they won't be used until birth.

Kidneys are functional and producing urine, which is released into the amniotic fluid.

Reflexes become more pronounced, and the baby may start sucking its thumb.

Size: About 3 inches long, similar to a peach.

Weight: Around 0.8 ounces.

Week 14:

Development:

The baby can now make facial expressions, such as frowning and squinting.

The neck becomes more defined, and the head lifts more upright.

The liver produces bile, and the spleen helps form red blood cells.

Taste buds begin to form, though there's no exposure to flavors yet.

External genitalia are now distinct enough to determine sex via ultrasound.

Size: About 3.5 inches long, comparable to a lemon.

Weight: Around 1.5 ounces.

Week 15:

Development:

The baby's body grows faster than the head, achieving more proportional development.

Bones in the middle ear begin to harden, potentially allowing the baby to detect muffled sounds.

The baby starts practicing breathing movements, drawing amniotic fluid in and out of the lungs.

The skin is still thin and translucent, showing developing blood vessels beneath.

Fine hair patterns (eyebrows and hair on the scalp) may start to appear.

Size: About 4 inches long, similar to an apple.

Weight: Around 2.5 ounces.

Week 16:

Development:

The baby's limbs are fully developed and capable of making coordinated movements.

The heart pumps about 25 quarts of blood per day through its tiny body.

Fingernails and toenails are well-formed and continue to grow.

The baby develops the ability to grip objects and may even hold onto the umbilical cord.

The eyes, though still closed, can sense light if a bright light is shone on the belly.

Size: About 4.6 inches long, comparable to an avocado.

Weight: Around 3.5 ounces.

Physical Development Milestones in Month 4

Movements Become Purposeful:

The fetus makes jerky movements that grow more coordinated. It stretches, yawns, and may even hiccup.

Facial Features and Expressions:

The face is fully developed, with more distinct eyebrows, a nose, and lips.

Nervous System Growth:

Nerves are being coated in myelin, which speeds up the transmission of signals between the brain and body.

Hearing:

The baby may begin to detect the mother's heartbeat, voice, or external noises, although these are muffled.

Organs:

The lungs, liver, and kidneys continue to mature.

Skeletal Growth:

Bones are solidifying and visible in ultrasounds.

Symptoms for the Mother During Month 4

Increased Energy: Many women feel less fatigued and have more stamina during this month.

Appetite Growth: With morning sickness subsiding, hunger often increases.

Weight Gain: Most women gain about 1–2 pounds per week in the second trimester.

Baby Bump: The uterus grows, making the pregnancy more visible.

Breast Changes: The breasts may continue growing as they prepare for lactation.

Quickening (First Movements): Some mothers may feel the baby's movements, especially if it's not their first pregnancy.

What to Expect Overall in Month 4

By the end of this month:

Size: The fetus is about 5.5 inches long, similar to a large bell pepper.

Weight: Around 6 ounces.

The baby is fully formed and growing rapidly, with all systems becoming more complex.

Month 4 marks an exciting transition for both the fetus and the mother. The fetus starts behaving more like a baby, with increased movement and sensitivity to stimuli.