Week 40: The Due Date Arrives, Most Babies Don't, and the Meeting Is Close

Week 40 is the due date. It is also, statistically, the week most first-time mothers do not deliver. About 4% of babies arrive exactly on their estimated due date; the rest arrive earlier or later, with first-time pregnancies skewing slightly past 40 weeks on average. The number was never a deadline. It was a midpoint of a normal range — 37 to 42 weeks, that obstetric practice settled on a century ago for cleanliness rather than precision. If you have not gone into labor yet, you are not late. You are in the second half of normal.

What happens this week is two things. First, the routine surveillance gets tighter. Your provider will check more often, sometimes twice a week, and may add a non-stress test or a quick ultrasound to confirm amniotic fluid is adequate and the baby is still moving well. Second, the conversation about induction begins to take shape. Most American practices offer induction at 41 weeks. Many offer it earlier on parental preference. The decision is, increasingly, a real conversation rather than a default.

This week

Your baby measures between 19 and 21 inches long and weighs anywhere from 6 ¾ to 10 pounds. The size range is wide because babies are now genuinely different sizes, a 6-pound baby and a 9-pound baby are both normal, both healthy, and both ready to be born. APA notes the bones have become hard, with the exception of the skull, which remains flexible to allow overlap during delivery. Newborns are born with two soft spots, fontanelles, that close at different intervals over the first two years.

Cleveland Clinic's summary of this stage notes the fetus achieves its final measurements of approximately 18-20 inches in length and 7-9 pounds in weight. The fat layer is in. The lungs are mature. The brain is approximately 90% of its newborn weight. The baby will, in some specific number of hours or days from now, take its first breath and convert from a placenta-fed organism to a lung-breathing one in a transition that takes about 30 seconds and rewires several thousand years of cardiopulmonary anatomy.

Movement remains the daily check. The pattern matters more than the count. If you know that your baby is typically active mid-morning and after dinner, you are watching for that. If movement has been steady all week and then drops off noticeably, that is the phone call, even at week 40, even at 4 a.m.

What's happening in your body

The symptoms that have been with you for weeks are still here. Back pain. Pelvic pressure. Frequent bathroom trips. Restless legs at night. Swelling that comes and goes with the day. The new sensations are mostly contraction-related.

The NHS lays out the signs of labor cleanly. Contractions feel like extreme period pains and become longer, stronger and more frequent as labor progresses. The mucus plug, the show, appears as sticky, jelly-like pink mucus and may come away in one or several pieces. Waters breaking presents as either a slow trickle or a sudden gush of water you cannot control; the fluid is clear and pale, sometimes faintly bloodstained at first. Call your provider, the NHS says immediately, for regular contractions every 5 minutes or more often, waters breaking, vaginal bleeding, decreased fetal movement, or contractions lasting longer than 2 minutes.

If the show passes but contractions have not started, you are still potentially days away from labor. If waters break, you are within 24 hours; most providers want you in the hospital quickly because the risk of infection rises with time after rupture. If contractions hold a regular pattern and intensify, you are in early labor, typically the longest phase, often eight to twelve hours for a first delivery, sometimes much longer or shorter.

APA describes the moment closer to delivery: crowning, when the baby's head stretches the vaginal opening, comes with a sensation often called the ring of fire, a burning that is then followed by a numb feeling as nerves are compressed. APA notes that the right move when crowning is to stop pushing and let the tissue stretch slowly, which reduces tearing. Your provider will coach you through this in real time.

The APGAR test happens at one minute and again at five minutes of life, a quick check of heart rate, breathing, muscle tone, reflex response, and color. APA notes that scores between 7 and 10 indicate the baby is in good shape and routine post-delivery care is sufficient. Most babies score 7-10. Lower scores trigger immediate intervention, which is the whole point of the test.

If you have not gone into labor by 41 weeks, your provider will likely begin a more formal conversation about induction. Multiple methods exist: prostaglandin gel to ripen the cervix, mechanical dilation with a balloon catheter, IV Pitocin to stimulate contractions, or membrane sweeping at a prenatal visit. None of them are emergencies. All of them work, with various combinations of comfort and time. Most are offered at 41 weeks and recommended at 41 to 42.

What your partner can do

The job at week 40 is to be the calm one in the room. Three concrete moves.

Know the exact route, the exact door, the exact parking. Have the bag in the car or by the door. Have the older kid coverage on standby. Have the dog plan ready. The labor moment is not the moment to be making decisions about logistics. Every decision you have already made is one fewer thing in the way of being present.

Time the contractions. Use the app. Time from the start of one contraction to the start of the next, and time the duration of each. The pattern that gets you to the hospital is typically the 5-1-1 rule: contractions five minutes apart, lasting one minute, for one hour. (Some practices use 4-1-1 for second babies or for parents who live far from the hospital.) Your provider will tell you the exact threshold to call.

When the moment comes, be present and quiet. Don't ask questions you can answer yourself. Don't crowd the room. Don't text family. Hold the hand. Bring the ice chip. Say the thing your partner needs to hear, not the thing that comes to mind. Couples often remember labor in terms of who their partner was during it; this is the day to be the version of yourself you would want your kid to read about.

Names we love this week

Week 40 has the texture of the meeting being imminent. The body has finished. The baby is ready. The name has, by this point, mostly chosen itself. The names that fit this week are the ones that carry threshold, names that sound like the door opening.

• Noah is the Hebrew Noach, meaning "rest" or "comfort." Top 5 in the US for a decade and a name that sounds gentle in any language.
• Emma is the Germanic ermen meaning "whole" or "universal." Top 5 since the late 2000s and still aging well.
• Atlas means "to bear" in Greek, the Titan who carries the heavens. A name with built-in weight for a baby arriving in the heaviest week of your life.
• Maya is a Sanskrit and Hebrew name with multiple meanings — "illusion," "water," and "dream", and carries warm cross-cultural durability.
• Benjamin — Hebrew "son of the right hand", for the day the baby arrives.
• Charlotte — French "free", a name that has earned its place at the meeting.
• River is the English nature name carrying the quality of motion. Three letters that sound like an arrival.
• Lucas — Latin "light-bringer", for the day the meeting happens.

Of these eight, Noah, Emma, Henry, and Theodore are in the current US top 25 — names that families have been quietly converging on for a decade. Atlas, Maya, and River are the rising tier. Iris is the quietly excellent middle, the kind of name that becomes a person and then stays one.

A small piece of advice for week 40: don't choose the name in advance of meeting the baby unless you are completely, both of you, sure. Most parents are. Some aren't, and meet the baby and discover the second-choice name is the actual answer. The hour after delivery is one of the strangest cognitive states two adults can share — flooded with hormones, exhausted, holding a person who an hour ago did not exist as a person. Give yourselves permission to use that hour. The top three from your wallet card are right there. The right one will be obvious. And if your due date passes without the baby — which is what happens to most first-time parents — remember that the date was a midpoint, the baby is still well, and the meeting is close.

Sources

• American Pregnancy Association — Week 40 of Pregnancy
• Cleveland Clinic — Fetal Development: Stages of Growth
• NHS — Signs That Labour Has Begun