Week 27: Last Week of the Second Trimester

This is the last week of the second trimester — next week begins the final stretch! Your baby is very active now, with busy brain activity that includes dreaming and established sleep patterns. You have come a long way, and there is so much to look forward to in the last 13 weeks.

Your baby weighs around 875 grams and measures about 37 cm from head to heel. The brain is incredibly active — it uses approximately half of all the energy the baby receives. REM sleep (dreaming sleep) is well established, and brain waves are beginning to resemble those of a newborn baby. Two out of three trimesters are complete!

Baby's Development

Size and Growth

Length: About 37 cm from head to heel
Weight: About 875 grams
Comparison: The size of a cauliflower

Key Developmental Milestones

Brain activity: Extremely active, with millions of new nerve connections forming daily
REM sleep: Your baby is dreaming! Brain activity clearly shows dreaming sleep
Brain waves: Beginning to resemble the patterns of a newborn baby
Lung maturation: Increased surfactant production, but not yet ready for air
Sleep patterns: Established periods of sleep and wakefulness
Hiccups: Rhythmic jerking movements — the diaphragm is practicing. Completely normal!
Eyelids: The baby opens and closes its eyes and responds to light
Taste and smell: Can distinguish between different flavors and smells in the amniotic fluid

REM Sleep and Dreaming

From week 27, REM sleep (Rapid Eye Movement) is well established in your baby. During REM sleep, the eyes move rapidly behind closed eyelids, and brain activity is high — this is the sleep phase in which dreams occur.

Nobody knows what the baby dreams about. The brain is likely processing sensory impressions — sounds, movements, touch, and light. It is a fascinating thought that your little one already has a form of inner experience.

REM sleep is important for brain development. It stimulates nerve connections and helps the brain mature. Your baby spends up to 70 percent of sleep time in REM sleep — far more than adults, who have only about 20 percent.

The Brain — An Energy-Intensive Supercomputer

The baby's brain is the most energy-intensive part of the body and uses approximately half of all the energy the baby receives through the placenta. The surface is beginning to develop the characteristic folds (gyri and sulci) that provide room for many more nerve cells than a smooth surface would allow.

The cerebral cortex is developing distinct layers, and specialized areas for vision, hearing, movement, and touch are taking shape. The cerebellum, which controls coordination and balance, is growing particularly fast during this period.

Your Body

Common Symptoms

Trimester shift: Energy may dip as the third trimester approaches
Back pain: The shifting center of gravity is straining the lower back
Leg cramps: Especially at night — can be caused by low magnesium
Night sweats: Hormonal fluctuations cause more sweating than usual
Mixed emotions: Joy and uncertainty about the approaching final trimester
Shortness of breath: The uterus is pushing the diaphragm upward
Pelvic girdle pain: Pain in the pelvis and pubic area may intensify

Leg Cramps — Causes and Remedies

Nighttime leg cramps are a very common complaint in the second and third trimesters. They can be caused by several things:

Low levels of magnesium or calcium
Increased strain on the legs from weight gain
Pressure from the uterus on nerves and blood vessels
Dehydration

Prevention:

Gently stretch your calves before bed
Eat magnesium-rich food: bananas, nuts, seeds, spinach, dark chocolate
Make sure you get enough calcium: dairy products, broccoli, almonds
Drink enough water throughout the day
Keep your feet warm at night
Avoid pointing your toes downward when stretching

If a cramp sets in:

Flex your foot upward toward your shin (dorsiflexion)
Gently stretch the calf
Massage the muscle
Walk around a little to release the tension

Talk to your midwife about magnesium supplements if leg cramps are frequent and bothersome.

Good to Know

Emotions at the Trimester Shift

It is normal to feel mixed emotions as the third trimester approaches. Some are extremely excited, while others feel uncertainty about the birth, parenthood, or how life will change. Many feel both at the same time.

It is important to talk about your thoughts — with your partner, a good friend, your midwife, or a healthcare provider. Persistent anxiety or low mood should be raised with your midwife or doctor, as there is good support available.

Birth Preparation Classes

Now is a good time to sign up for birth preparation classes. Most classes start around weeks 28–32, and many fill up quickly.

Options:

Hospital classes: Most maternity units offer free classes with information about the hospital, birth, and breastfeeding
Community classes: Many areas offer midwife-led classes
Private classes: Midwives and doulas often offer more personalized courses
Online classes: A flexible option you can do from home
Hypnobirthing: Focuses on relaxation, breathing techniques, and mental preparation

Classes typically cover:

The phases of labor and what happens
Pain relief (epidural, gas and air, natural methods)
Breathing and relaxation techniques
The partner's role during birth
Breastfeeding and the first days with the baby

Amniotic Fluid — Your Baby's Environment

Amniotic fluid is a fascinating environment:

Facts about amniotic fluid:

The baby swallows up to 500 ml daily
Amniotic fluid is completely renewed every three days
It contains proteins, carbohydrates, lipids, and electrolytes
Its flavor is influenced by what you eat
Volume is approximately 700–800 ml at week 27

Research shows that babies exposed to a varied diet in the womb are often more open to different flavors after birth. A great reason for a varied and nutritious diet!

Celebrate the Milestone

You are done with two out of three trimesters — 67 percent of pregnancy is complete!

Ways to celebrate:

Take a pregnancy photo and save it as a memory
Write a letter to your baby about what you are thinking and feeling
Have a special dinner with your partner
Share the news with family and friends
Buy something small for the baby to mark the occasion

What Awaits in the Third Trimester?

The third trimester (weeks 28–40) brings new experiences:

For your baby:

Rapid weight gain (about 200 g per week)
Lungs maturing to independence
Explosive brain growth
Baby turning into birth position

For you:

Prenatal appointments become more frequent
Birth preparation classes
Final preparations at home
Possible sick leave toward the end

Practical preparations:

Packing a hospital bag (from week 35)
Finishing the nursery
Batch cooking and freezing meals
Planning parental leave and work arrangements
Creating your birth plan

For Your Partner

Talk together about the third trimester and birth — share expectations and any concerns openly
Sign up for birth preparation classes together, so you both feel prepared
Help with stretching exercises for the calves in the evening — it can prevent nighttime cramps
Celebrate the milestone together — two out of three trimesters are done!
Start discussing parental leave arrangements

Tips for Week 27

Start birth preparation: Look into classes at your maternity unit or with private midwives, and start thinking about your birth preferences
Stretch your calves: Simple stretching exercises for the calves before bed help prevent nighttime cramps
Take a pregnancy photo: This week marks the end of the second trimester — save it as a memory
Magnesium-rich food: Nuts, seeds, bananas, and dark chocolate can help prevent leg cramps
Varied diet: Eat many different flavors — the baby tastes the amniotic fluid and becomes familiar with your food
Pelvic floor exercises: Daily exercises are more important than ever as the third trimester approaches
Talk about your feelings: Share thoughts and concerns with your partner, a friend, or your midwife

When to Contact a Doctor

Contact your doctor or midwife if you experience:

Sudden reduction in fetal movements
Leaking fluid from the vagina (could be amniotic fluid)
Regular contractions that do not stop with rest
Strong pains that come and go at regular intervals
Fever over 38 degrees Celsius
Persistent headache with vision disturbances
Severe swelling in the face or hands

Did You Know?

Your baby is dreaming: At week 27, your baby has REM sleep — the sleep phase in which dreams occur. Nobody knows what the baby dreams about, but brain activity clearly shows dreaming sleep. Your baby spends up to 70 percent of sleep time in REM sleep!
The brain is energy-intensive: Your baby's brain waves are now beginning to resemble those of a newborn. The brain uses approximately half of all the energy the baby receives through the placenta — it is the most energy-intensive part of the body.
Hiccups are training: Hiccups in the belly are your baby training the diaphragm! These rhythmic jerking movements are completely normal and can be felt as gentle, regular tapping. Some babies hiccup several times a day. It is a good sign — it means the breathing reflex is maturing.
Two out of three are done: You have now completed two out of three trimesters — meaning approximately 67 percent of pregnancy is behind you. A wonderful milestone worth celebrating!
Flavor memory: Your baby remembers flavors from the amniotic fluid. If you eat a lot of a particular food now, your baby may show interest in that flavor after birth. A varied diet gives your baby a wide flavor palette.

Common Questions About Week 27

Are nighttime leg cramps normal?

Yes, nighttime leg cramps are very common in the second and third trimesters. They can be caused by low levels of magnesium or calcium, increased strain on the legs, or pressure from the uterus on nerves and blood vessels. Stretch your calves gently before bed, eat magnesium-rich food (bananas, nuts, seeds), and keep your feet warm. Talk to your midwife about magnesium supplements if cramps are frequent.

When should I start a birth preparation class?

Most classes recommend starting between weeks 28 and 32. Many classes fill up quickly, so it is wise to sign up now. Your hospital or birth center typically offers classes, and there are also private and online options. Look into what is available and choose what suits you best.

Is it normal to have mixed feelings about pregnancy?

Absolutely. It is completely normal to alternate between joy, excitement, uncertainty, and worry. Your body is going through a major change, your life is about to transform, and there is a lot to process. Talk with your partner, a good friend, or your midwife if you need to talk things through. If persistent anxiety or low mood is affecting you — reach out to your midwife or doctor.

What does it mean when the baby has hiccups?

Baby hiccups feel like regular, rhythmic jerking movements and are completely normal. They are a sign that the diaphragm and breathing reflex are maturing — important practice for the first breath after birth. The hiccups are not uncomfortable for the baby and usually last a few minutes. There is no reason for concern, even if they occur several times a day.

What should I do to prepare for the third trimester?

The most important things are to sign up for birth preparation classes, start thinking about your birth preferences, plan your parental leave, and begin practical preparations like the nursery and equipment. Batch cooking and freezing meals is also a great investment for the postpartum period. Keep up with daily pelvic floor exercises too.

How much magnesium do I need?

According to WHO recommendations, the daily intake of magnesium for pregnant women is around 310–360 mg depending on age. Good sources include nuts (especially cashews and almonds), seeds (pumpkin and sunflower), bananas, dark chocolate, spinach, and whole grains. A supplement may be considered for frequent leg cramps — talk with your midwife.

Next week: Welcome to the third trimester — two thirds of pregnancy are complete!