An expectant mother holds ultrasound images of her baby and smiles.
Expect a lot of wiggling and kicking as your baby grows inside a tight space during the final trimester. (For Spectrum Health Beat)

It’s nearly “D” time. Delivery time, that is.

In week 28 of your pregnancy, you’ve finally reached the final trimester.

With only 3 to 5 percent of babies born on their actual due dates, there’s no surefire way to predict your baby’s delivery date. We’ve talked in the past about early babies and late babies.

So your baby could come any day now.

As you enter the final weeks of pregnancy, baby is still growing and gaining more fat.

Your little bundle begins this final trimester at about 2.5 pounds, 10 inches. As he grows, his movements become stronger—and mom can certainly feel them.

At the start of the trimester, baby can open his eyes. His toenails and fingernails are growing and all the bones are getting harder and stronger. His skull stays more flexible and soft, however, which makes for an easier delivery.

Baby’s brain is still growing, too, with different regions of the brain beginning to fully form. March of Dimes tells us that at week 35, a baby’s brain weighs about 2/3 what it will at week 39 or week 40.

Hair is growing on baby’s head, too, but only if your baby will have hair.

Babies can also get the hiccups at this stage. Have you felt those little jerky movements when baby has the hiccups? Some get them more often than others.

At about week 30 your baby is practicing breathing, although he doesn’t really breathe, per se. The oxygen and nutrients he needs in utero come via the umbilical cord, so for now he’s only practicing the breathing movements he’ll need after birth.

At week 31, your little one is beginning to put on some fat and weight. By week 32, he’ll weigh about 4 pounds.

Our second baby was born in week 32 at 4 pounds, 1 ounce. She came into this world small but healthy, although her tiny size meant she still had to spend three weeks in the NICU.

At about 34 weeks a baby’s skin becomes thicker, less translucent and less wrinkled.

Throughout the first trimester, the baby is also coated in vernix, that white or off-white creamy, cottage cheesy substance you’ll see on the baby at birth. An article in the National Library of Medicine tells us that vernix is unique to humans. It’s made up of water, lipids and proteins.

As I read about vernix, I learned something new.

I always knew that vernix acts as a sort of barrier between the baby and the amniotic fluid. It’s why babies don’t look as water-logged as we’d expect at delivery. If we stay in a tub or pool for even a short period, our skin gets wrinkled and soft.

Babies are protected by vernix, which also helps regulate their temperature and acts as a lubricant during delivery.

The new piece of information I recently learned? Babies lose some vernix in utero, and they swallow it along with amniotic fluid. This helps with the development of the gut.

Many parents don’t have the vernix washed off their baby after birth, since vernix has many great properties.

Another interesting thing: A baby’s length doesn’t change much after week 35 or so, although the baby will continue to gain weight up until delivery day. Babies can typically gain up to half a pound a week throughout the last month of pregnancy.

In those last few weeks, baby is getting a bit crowded in there, taking up all the available room. Moms will definitely feel this.

It’s also important to know that your baby is already developing sleep patterns. Hopefully some of those naps are happening at night.

As delivery time nears, baby will eventually get into a head-down position and drop lower into the pelvis. Soon enough, your baby will be born.

Pregnancy should be an exciting time full of wonder and amazement for you and your family.