Trillions of connections are forming in your baby's brain. At 31 weeks, the fetal brain is working faster than ever, processing signals from all five senses and controlling complex bodily functions. The baby is also spending a significant amount of time in REM sleep—the deep sleep stage where dreaming occurs.
🍼 What's Happening With Your Baby
Now the size of a coconut, the baby is gaining about half a pound a week. The fat accumulation is crucial; it plumps up the arms and legs, making them look less frail and more like a newborn.
The reproductive organs are finalizing. A boy's testicles are actively descending from his abdominal cavity into the scrotum, though sometimes this process isn't completed until after birth.
The lungs are practicing breathing movements more consistently, inflating and deflating with amniotic fluid to strengthen the diaphragm.
🤰 What You're Feeling This Week
You might find yourself waddling. As the hormone relaxin loosens your pelvic joints to prepare for childbirth, your gait naturally changes to compensate for the shifting center of gravity and the instability in your hips.
Your breasts are preparing for lactation. They may feel heavy, tender, and you might notice small bumps on the areolas (Montgomery's tubercles) which secrete an oil to lubricate the nipple for nursing.
Shortness of breath is common, but it's important to differentiate it from severe breathlessness. If you suddenly cannot catch your breath, feel chest pain, or have a rapid heartbeat, seek immediate medical attention to rule out a pulmonary embolism.
The Brain Works Overtime
The rapid development of nerve connections means the baby can process information from the outside world. They react more strongly to your voice and sudden loud noises, often visibly jumping or kicking.
✅ What To Do This Week
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Pack your hospital bag — It's better to have it sit in the closet for two months than to pack it while experiencing painful contractions. Include comfortable clothes, nursing bras, toiletries, and an extra-long phone charging cord.
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Start tracking fetal movements diligently — At 31 weeks, kick counting is vital. Any significant decrease in movement should be evaluated by a healthcare professional immediately.
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Watch for signs of preterm labor — True labor contractions feel different from Braxton Hicks. If you feel regular tightening that increases in intensity, pelvic pressure, or back pain, call your doctor.
"Your hips are widening, your stride is changing. Your body is biologically remodeling itself to become a doorway. The discomfort is the physical manifestation of that preparation."
— A Note From Your Body, Week 31