Pregnancy Milestones: What to Expect When You Have 100 Days to Go

Published June 2026  ·  5 min read

One hundred days until your due date sits right around the start of the third trimester — roughly week 26 or 27 of pregnancy. It's far enough out that there's still time to prepare properly, and close enough that the preparation actually needs to start. Here's what's happening with your baby, what your body is doing, and what still needs your attention before the big day.

What's Happening With Your Baby at 100 Days Out

At around 26–27 weeks, your baby weighs roughly 1.5 to 2 pounds and is about 14 inches long. The developments happening right now are significant:

• Lungs are maturing. The air sacs are developing and the baby is practicing breathing movements with amniotic fluid. Lung development will continue through the final weeks.
• Eyes are opening. Eyelids, which have been fused shut since early development, begin to open around week 26. Your baby can now detect light and dark through the uterine wall.
• Brain activity is increasing. Brain wave patterns resembling sleep cycles have been detected at this stage. The brain is growing rapidly.
• Movement is strong and regular. Kicks, rolls, and hiccups are common and often noticeable. Your provider may begin asking you to track kick counts around this time.

Babies born at 26–27 weeks are considered extremely premature but have survival rates above 80% with modern neonatal care. Each additional week significantly improves outcomes. The goal, of course, is to reach full term — but knowing where your baby is developmentally provides useful context.

What Your Body Is Doing

The third trimester brings a distinct set of physical changes. Heartburn tends to worsen as the growing uterus puts pressure on the stomach. Sleep becomes more difficult — finding a comfortable position is harder, and nighttime trips to the bathroom increase. Swelling in the feet and ankles is common and normal, though sudden or severe swelling warrants a call to your provider.

Braxton Hicks contractions — irregular, painless tightening sensations — often become more noticeable in the third trimester. They're your uterus rehearsing for labor and are not a cause for concern unless they become regular, painful, or accompanied by other symptoms.

Fatigue typically returns after the relative energy of the second trimester. This is the time to start taking rest seriously rather than pushing through it.

What Needs to Happen in the Next 100 Days

With roughly 14 weeks remaining, here's what to prioritize:

The Emotional Reality of the Final 100 Days

Anxiety and excitement exist in the same space at this stage of pregnancy, often at the same time. It's common to feel completely ready and completely unprepared within the same afternoon. Both feelings are normal, and neither one is a reliable indicator of how you'll actually handle what's coming.

One thing that consistently helps: reducing abstraction. "The baby is coming soon" is a thought that can spiral. "I have 67 days and I need to pack a hospital bag and pick a pediatrician" is a thought you can act on. Concrete tasks with concrete timelines cut through the ambient anxiety more effectively than reassurance does.

One hundred days is not a long time. It's also enough time to be ready. The key is starting now rather than waiting until it feels urgent — by then, it already is.