The Stages of Labor

Contents

1. The first stage opens the cervix
2. The second stage moves the baby
3. The third stage and the vocabulary of labor

Candace Cooley’s obstetric work has included delivering babies and caring for pregnancies at ordinary and at high risk, and a vaginal birth follows a sequence that obstetrics has long divided into stages. Picture a woman near the end of a first pregnancy on an ordinary weekday afternoon. Since lunch she has had a low, dull ache in her back, and in the bathroom she notices a small streak of pink, sticky mucus. Her abdomen tightens now and then, hard under her hand, and then softens. Nothing about it is dramatic, and she is not sure whether anything has started. The NHS guide to the signs of labor would recognize each of these: backache, the loss of the mucus plug that seals the cervix, known as a show, and contractions in which the womb tightens and relaxes. A show means the cervix is beginning to open, but labor may follow quickly or take a few days, and sometimes there is no show at all.⁵

Clinicians describe what happens next in stages because each part of labor has its own task, its own pace and its own signs. MedlinePlus summarizes the scheme in three parts: the first stage opens the cervix, the second moves the baby down and out, and the third delivers the placenta. Labor usually begins between 37 and 42 weeks of pregnancy.⁶

Figure

The sequence of labor

1. 01
   Latent phaseThe cervix softens and starts to open; contractions are irregular and this is usually the longest part.
2. 02
   Established laborFrom about 4 centimeters, with stronger, more regular contractions, until the cervix is fully open.
3. 03
   Second stageFrom full dilation until the baby is born, with pushing during contractions.
4. 04
   Third stageThe uterus contracts and the placenta comes away and is delivered.

The first stage opens the cervix

The first stage itself has two parts. In the latent phase, the NHS overview of labor explains, the cervix softens and begins to dilate while contractions are irregular, ranging from mildly uncomfortable to painful, with no set pattern. The contractions do the work of every stage: as the womb muscle tightens, it presses the baby downward and draws the cervix open, and as it relaxes the hardness under the hand eases.⁵ It can take many hours or even days, and it is usually the longest part of labor. Light meals and fluids, staying gently active by day and resting at night are the usual suggestions, and a woman who arrives at hospital this early may be sent home for a while.⁴

The latent phase overlaps with the contractions many women feel in late pregnancy. MedlinePlus describes Braxton Hicks contractions as short, painless, irregular and without effect on the cervix, and notes that the steps toward labor can drag on for days. Other signs may come first: lightening, when the baby’s head drops into the pelvis, often weeks before a first birth; looser stools; leaking fluid when the waters break, after which contractions usually start within a day.⁷

Figure

Braxton Hicks contractions and true labor

	Braxton Hicks	True labor
Timing	Irregular, at no set interval	Regular, closing to about 5 to 10 minutes apart
Length	Typically short	30 to 70 seconds, growing longer
Feeling	Usually not painful	Stronger over time, reaching the lower back and upper belly
Effect on the cervix	No change that signals labor	Thins and opens the cervix
Response to rest	May fade	Continues whatever the woman does

Established labor begins when the cervix has opened to about 4 centimeters and contractions become stronger and more regular. The cervix must reach about 10 centimeters, called full dilation, for the baby to pass. In a first pregnancy the NHS gives 8 to 18 hours as the usual time from established labor to full dilation, and often 5 to 12 hours in a second or third.⁴ MedlinePlus puts the same width at about four inches and notes that the cervix also thins, a change called effacement.⁶

During this stage the midwife or doctor checks the mother’s blood pressure, pulse and temperature, and times the contractions for frequency, length and strength. NHS inform adds that a vaginal examination may be offered to see how far the cervix has opened and where the baby’s head sits, and that the baby’s heart is checked every 15 minutes in the first stage.² The methods are explained in fetal heart rate monitoring.

The second stage moves the baby

The second stage runs from full dilation until the birth. The baby moves down the birth canal, and many women feel an urge to push that resembles the need to empty the bowel; with an epidural that urge may be faint or absent. The NHS describes a range of birth positions, from sitting and side lying to kneeling on all fours, and says pushing should usually last no longer than three hours with a first baby and two hours after an earlier birth.⁴ As the head is about to emerge, the woman is asked to stop pushing and breathe in short puffs so the head is born slowly, giving the tissue between the vagina and anus time to stretch. The rest of the body usually follows within one or two contractions. Sometimes a small cut called an episiotomy is suggested to avoid a tear or to hasten the birth; the area is numbed first, and the cut or any large tear is stitched afterward.⁴ MedlinePlus calls the moment the scalp comes into view crowning.⁶

The baby’s head changes during this passage. NBC News reported on French researchers who captured 3D magnetic resonance images of seven babies in the birth canal, showing the bones of the skull overlapping so the head could fit, and more compression of the brain than the team expected. The researchers stressed that vaginal birth is overwhelmingly safe and that problems arise in a very small number of babies, by one neonatologist’s estimate one in a thousand or fewer, and that the aim is imaging software that might one day predict which heads will struggle to mold.³

Figure

Typical timings

established labor to full dilation in a first pregnancy

8 to 18 hours

the same span in a second or third pregnancy

5 to 12 hours

usual upper limit for pushing with a first baby

3 hours

usual upper limit for pushing after an earlier birth

2 hours

Pain relief changes the pace of this stage. The American Society of Anesthesiologists reports that an epidural is used in about 77 percent of American deliveries and is the commonest form of labor pain relief, alongside spinal blocks, injected pain medicines, nitrous oxide and methods without drugs such as massage, breathing, visualization and warm water. General anesthesia, the one option that removes consciousness, is kept mainly for an emergency cesarean or urgent bleeding.⁸ An NBC News report on California birth records found the pushing stage ran two to three hours longer with an epidural, and noted that the labor norms most clinicians still use date from the 1950s, when far fewer women had one; the researchers called for those norms to be revisited.¹ The mechanics are covered in epidural analgesia, and the alternative route of birth in cesarean birth.

The third stage and the vocabulary of labor

The third stage begins after the baby is born and ends when the placenta is delivered. The NHS describes two ways to manage it. In active management an injection is given to make the womb contract, the cord is cut between one and five minutes after birth, and the placenta is drawn out by gentle traction, usually within half an hour; this lowers the risk of heavy bleeding but makes nausea more likely and afterpains worse. In physiological management no injection is given, the cord is left until it stops pulsing, and the placenta can take up to an hour to come away.⁴ Skin to skin contact and a first feed within the hour usually happen during this time.⁴

A handful of terms covers most of what is said in the delivery room. Latent phase and established labor are the two halves of the first stage. Effacement is the thinning of the cervix and dilation its opening, measured in centimeters up to about 10. A show is the mucus plug coming away, and the waters breaking is the opening of the fluid filled sac around the baby. Braxton Hicks contractions are the irregular tightenings of late pregnancy. Lightening is the baby settling lower in the pelvis. Crowning is the first sight of the scalp. Active and physiological management are the two approaches to the third stage. With these words a woman can follow her own labor as it is described to her, and the details of how her labor should be managed are best worked out with her own midwife or obstetrician.