The Waiting Room
Thirty-seven weeks used to be called "full term." For decades, that label gave both patients and providers the impression that babies born at 37 weeks were as ready as babies born at 40. In 2013, ACOG and the Society for Maternal-Fetal Medicine redefined the terminology because the data showed otherwise [1].
The new designations:
- Early term: 37 weeks 0 days through 38 weeks 6 days
- Full term: 39 weeks 0 days through 40 weeks 6 days
- Late term: 41 weeks 0 days through 41 weeks 6 days
- Postterm: 42 weeks 0 days and beyond
The distinction matters. Babies born at 37 or 38 weeks have higher rates of respiratory problems, feeding difficulties, temperature instability, jaundice, and NICU admission compared to those born at 39 or 40 weeks [1][5]. The difference is small for any individual baby, but it's consistent enough that ACOG recommends against elective delivery before 39 weeks unless there's a medical reason [1].
So you're early term. Your baby is developed. They would likely do well if born today. But "likely do well" and "optimally ready" are different things, and the next two weeks provide measurable benefit.
Your Baby at Thirty-Seven Weeks
Your baby is about the size of a winter melon, measuring approximately 19.1 inches (48.5 cm) from head to heel and weighing around 6.3 pounds (roughly 2.9 kilograms) [2][4]. The growth continues at about half a pound per week.
The brain is still building. Between 35 and 39 weeks, the brain increases in weight by roughly one-third. Neural connections involved in coordinating breathing, feeding, temperature regulation, and sleep-wake cycles are still forming and strengthening [2]. A baby born at 37 weeks has a less mature brain than one born at 39 weeks, and those two weeks of development translate to better feeding ability, more stable body temperature, and fewer breathing problems.
The lungs are almost there. Surfactant production is robust, and the lungs are structurally complete. For most babies at 37 weeks, the lungs can support breathing outside the womb. "Most" is the operative word. A small but meaningful percentage of babies born at 37 weeks still need respiratory support that wouldn't have been necessary at 39 weeks.
Fat deposition continues. Your baby is adding about 14 grams of fat per day, which builds the insulation layer needed for temperature regulation after birth. The chubbiness you'll see at delivery is functional, not decorative.
Toenails have reached the tips of the toes [4]. One of those tiny details that somehow makes the whole thing feel more real.
Cervical Checks: The Numbers That Mean Less Than You Think
Starting around 37 weeks, your provider may offer a cervical exam at your weekly visit. The exam checks three things:
- Dilation: How open the cervix is, measured in centimeters (0 to 10). Full dilation for delivery is 10 cm.
- Effacement: How thin the cervix has become, measured as a percentage. A thick cervix is 0% effaced; a paper-thin one is 100%.
- Station: How far the baby's head has descended into the pelvis, measured from -3 (high) to +3 (crowning).
Here's what cervical checks can tell you: the current state of your cervix at one moment in time.
Here's what they cannot tell you: when labor will start.
A woman can be 3 cm dilated for three weeks before labor. Another can go from 0 cm to fully dilated in a single afternoon. The cervix's state at any given appointment is a snapshot, not a forecast. Cervical checks can be uncomfortable (sometimes quite uncomfortable), and they're entirely optional. If you'd rather skip them, tell your provider. No pressure.
Three Weeks from the Due Date
Everything hurts, and that's the baseline. Pelvic pain, back pain, hip pain, rib pain, and a general sense of heaviness that permeates everything from walking to sitting to lying down. Your body is carrying a small watermelon's worth of baby plus placenta, amniotic fluid, and expanded blood volume. The discomfort is proportional to the achievement.
False labor will mess with your head. Braxton Hicks contractions at 37 weeks can be strong enough to make you wonder if "it's time." The distinction: true labor contractions come at regular intervals, get progressively stronger, and don't stop when you rest or drink water. False labor contractions are irregular, ease up with position changes, and don't progressively intensify [3]. When in doubt, call your provider. They would much rather take your call than have you sit at home wondering.
Nesting instincts are intense. The urge to organize, clean, prepare, and perfect everything in the baby's environment can feel almost compulsive. You may find yourself reorganizing the nursery at 11 p.m. or deep-cleaning the bathroom grout at 36 weeks pregnant. This is hormonally driven and evolutionarily ancient. Channel it productively, but also rest. The baby does not care about grout.
"Everyone asks 'are you ready?' and the honest answer is no." Full-term status arrives whether you feel prepared or not. The nursery might not be finished. The car seat might not be installed. You might not have settled on a name. Readiness is not a prerequisite for parenthood. No one is fully ready. The parents who look ready are simply better at performing confidence. Your baby does not need a perfect setup. Your baby needs you, and you are already here.
The "am I ready" spiral. You might not feel ready. For labor, for parenthood, for the enormous shift that's about to happen. That feeling is universal and doesn't predict anything about your ability to parent well. Readiness for parenthood isn't a feeling you arrive at before the baby comes; it's something that builds in real time, one day at a time, after they're here.
When to Go to the Hospital
Since you're now at the stage where labor could realistically begin, here are the signs [3]:
Call your provider when:
- You think you might be in labor
- You're having regular contractions that are getting closer together and stronger
- You lose your mucus plug (a thick, sometimes blood-tinged discharge)
- You're unsure whether what you're feeling is labor
Go to the hospital when:
- Your water breaks (even without contractions)
- You're having heavy vaginal bleeding
- Contractions are coming every 5 minutes, lasting 1 minute each, and this pattern has persisted for 1 hour (the 5-1-1 guideline)
- You experience constant, severe pain without relief between contractions
- You notice a significant decrease in fetal movement
When in doubt, go. Every labor and delivery unit would rather evaluate you and send you home than have you wait too long.
What MomDoc Wants You to Know
Week 37 is a study in patience. You're so close, and every part of your body knows it. The temptation to rush delivery is real, especially when sleep is nearly impossible and everything aches.
But these last weeks matter. The brain growth happening right now will serve your baby for their entire life. The fat accumulating under their skin will keep them warm in those first hours. The lung maturation happening between 37 and 39 weeks reduces the risk of breathing difficulties at birth [1][5].
You are doing something hard. Three more weeks to your due date. Your baby's toenails reach their toes. Their lungs practice with every faux breath. And somewhere in the dark of your pelvis, a tiny person is getting ready to meet the one whose heartbeat has been their soundtrack for nine months.