Chorevia

Day 259 of 280 · 37 weeks

Term, and early term

Last reviewed · 3 min read · 9 sources · Plain-text version

Thirty-seven weeks. The NHS calls your baby full term now; US guidance calls it early term. Today you learn both words, and the question to ask about 39.

Size this week
about the length of a leek
Length this week
around 48.6 cm from head to heel
A woman with a full, low bump in a loose white shirt standing at a kitchen counter with a mug, smiling at a wall calendar, a toddler's drawing taped beside it, soft morning light.

Thirty-seven weeks. It's a milestone with two names, depending on who you ask, and both are true. Today is about what they mean, and about one question worth having ready.

Your baby

A single leek with its green top on a plain pale wooden table, soft window light.

Around now your baby is around 48.6cm long from head to heel, about the length of a leek (NHS). The NHS calls this "full term": your baby is probably big enough, and mature enough, to survive in the outside world, though you may have a few more weeks of waiting (NHS).

US guidance draws the line later. NICHD calls 37 and 38 weeks "early term" and defines full term as 39 weeks through 40 weeks and 6 days; babies born at 37 or 38 weeks face more health risks than those born at 39 or 40 (NICHD). Both can be true at once: a baby born today would most likely do well, and a baby who waits gets a little more time to finish.

Your body

The practical meaning is about scheduling, not about labor that starts on its own. The CDC says: "Unless there is a medical need, delivery should not be scheduled before 39 weeks of pregnancy" (CDC). NICHD gives the reason: if there's no medical reason to deliver earlier, it's best to deliver at or after 39 weeks, so the lungs, brain, and liver can fully develop (NICHD). The Office on Women's Health says the same of cesareans (OWH).

Medical reasons are real, and they're the exception the rule is built around. With preeclampsia, for example, MedlinePlus says that at about 37 weeks the baby is usually developed enough to be healthy outside the womb, so providers often recommend delivery (MedlinePlus).

Try today

  1. The thirty-nine-weeks note

    Time: 5 minutes

    1. On your appointment note, write: "Is there a medical reason before 39?" (CDC).

    2. Use it only if a date before 39 weeks comes up, for an induction or a cesarean.

    3. If the answer is yes, ask what the reason is and write it down, so you both understand the plan.

    4. If the answer is "it would be convenient," ask what waiting would mean instead (OWH).

    Make it work:

    This isn't a challenge to your provider. It's the question they'd want you to ask, and a good answer is reassuring.

Watch for

  • Normal

    quieter spells between busy ones.

    Call your provider

    if the baby's movement suddenly decreases and stays low after you eat a snack and lie down for a few minutes (MedlinePlus).

  • Normal

    tightenings that are irregular and fade when you move (OWH).

    Call your provider

    when contractions become stronger, at regular and increasingly shorter intervals (OWH).

  • Normal

    feeling short of breath on the stairs.

    Call 911

    or go to an emergency room for severe chest pain or shortness of breath that doesn't go away (MedlinePlus); trouble breathing and a fast-beating heart are on the CDC's urgent list (CDC).

For you

Here's the plain version. If labor starts on its own from today, your baby is probably big enough and mature enough for the outside world (NHS), and you call and go in. If someone suggests delivering before 39 weeks, there should be a medical reason (CDC). Two rules, no contradiction.

And if the baby comes this week or next, these notes can stop. The baby's day-by-day notes start at your first month.

Sources

This guide is general education that summarizes published research and guidance from groups like the American Academy of Pediatrics, the CDC, and the WHO. It isn’t medical advice, and every child develops on their own timeline. Your pediatrician knows your child; if something feels wrong, call them. In an emergency, call 911.

Get each day’s note the morning it applies

Add your due date to a free Chorevia household, and every morning until the birth the day's note arrives in the app and by email: what's forming, what your body is doing, one thing to try, what to watch for, and a word for you.

Create your household